Brocade ServerIron ADX Server Load Balancing Guide, 12.5.02

53-1003452-01November 2014

Brocade ServerIron ADXServer Load Balancing Guide

Supporting Brocade ServerIron ADX version 12.5.02

Copyright © 2014 Brocade Communications Systems, Inc. All Rights Reserved.

ADX, AnyIO, Brocade, Brocade Assurance, the B-wing symbol, DCX, Fabric OS, ICX, MLX, MyBrocade, OpenScript, VCS, VDX, and Vyatta are registered trademarks, and HyperEdge, The Effortless Network, and The On-Demand Data Center are trademarks of Brocade Communications Systems, Inc., in the United States and/or in other countries. Other brands, products, or service names mentioned may be trademarks of their respective owners.

Notice: This document is for informational purposes only and does not set forth any warranty, expressed or implied, concerning any equipment, equipment feature, or service offered or to be offered by Brocade. Brocade reserves the right to make changes to this document at any time, without notice, and assumes no responsibility for its use. This informational document describes features that may not be currently available. Contact a Brocade sales office for information on feature and product availability. Export of technical data contained in this document may require an export license from the United States government.

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Brocade Communications Systems, Incorporated

Corporate and Latin American HeadquartersBrocade Communications Systems, Inc.130 Holger WaySan Jose, CA 95134 Tel: 1-408-333-8000 Fax: 1-408-333-8101 E-mail: [email protected]

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Contents

Preface

Document conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13Text formatting conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . .13Command syntax conventions . . . . . . . . . . . . . . . . . . . . . . . . . . 14Notes, cautions, and warnings . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Brocade resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Contacting Brocade Technical Support . . . . . . . . . . . . . . . . . . . . . . . 15Brocade customers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15Brocade OEM customers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Document feedback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Chapter 1 Features and Enhancements

Release 12.5.02 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Release 12.5.01a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Release 12.5.01 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Release 12.5.00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Release 12.4.00a . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Release 12.4.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Release 12.3.01 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Release 12.3.00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Release 12.2.1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

Release 12.2.0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Release 12.1.00 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Chapter 2 Server Load Balancing

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27How SLB works. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28Load-balancing predictor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28Sticky connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34Application port groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35Concurrent connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35Remote Servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36Direct Server Return . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

ServerIron ADX Server Load Balancing Guide 153-1003452-01

Configuring basic SLB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38Configuration guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39Defining the real servers and real application ports. . . . . . . . .39Defining a virtual server (VIP) . . . . . . . . . . . . . . . . . . . . . . . . . . .40Defining a virtual server name . . . . . . . . . . . . . . . . . . . . . . . . . . 41Binding virtual and real servers . . . . . . . . . . . . . . . . . . . . . . . . . 41

Changing the Load-Balancing Predictor Method . . . . . . . . . . . . . . .42Configuring a weighted predictor . . . . . . . . . . . . . . . . . . . . . . . .43Configuring dynamic weighted predictor . . . . . . . . . . . . . . . . . .44Configuring the smooth factor . . . . . . . . . . . . . . . . . . . . . . . . . .46

Real server ports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Disabling or re-enabling application ports . . . . . . . . . . . . . . . . .48Globally disabling application ports . . . . . . . . . . . . . . . . . . . . . .48Disabling SLB to a server when an application goes down . . .49Slow-start mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49Enabling or disabling the keepalive health check . . . . . . . . . . .50Configuring a real port as TCP only or UDP only . . . . . . . . . . . .50Configuring a stateless port . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Adding a source IP address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

Source NAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .54Enabling source NAT globally . . . . . . . . . . . . . . . . . . . . . . . . . . .56Enabling source NAT on a real server. . . . . . . . . . . . . . . . . . . . . 57Configuring a shared source IP address for NAT . . . . . . . . . . . . 57Configuring shared source NAT IP addresses within a VIP group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58Source NAT to packets from specified source IP addresses. . .58Client subnet based source NAT . . . . . . . . . . . . . . . . . . . . . . . . .58Minimizing source-IP and source-NAT-IP requirements for large deployments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59IPv6 Source NAT ACL Support . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Increasing the maximum of source-NAT IP addresses . . . . . . .62

Remote server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64

Sticky and concurrent connections . . . . . . . . . . . . . . . . . . . . . . . . . .64Configuring sticky ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .64Configuring stickiness based on client’s subnet . . . . . . . . . . . .65Setting the sticky age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66Preserving a sticky session when the health check is down . .66Allowing sticky ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67Increasing the sticky-age per VIP longer than 60 minutes . . . .67Sticky connection return from backup server to primary . . . . .68Group sticky: Layer 4 SLB to server group . . . . . . . . . . . . . . . . .69Enabling a concurrent port . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72Configuring virtual source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72

Application port grouping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73Tracking primary ports. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73Track port group function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74

2 ServerIron ADX Server Load Balancing Guide53-1003452-01

Primary and backup servers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76Designating a real server as a backup . . . . . . . . . . . . . . . . . . . .78Enabling a VIP to use the primary and backup servers. . . . . . .78Configuration example. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79Designating a real server port as a backup . . . . . . . . . . . . . . . .80Per server based real server backup . . . . . . . . . . . . . . . . . . . . . 81

Configuring Direct Server Return . . . . . . . . . . . . . . . . . . . . . . . . . . . .84Configuring L2 Direct Server Return. . . . . . . . . . . . . . . . . . . . . .85Configuring L3 Direct Server Return. . . . . . . . . . . . . . . . . . . . . .90

Displaying server information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92

Port ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .94Defining a port range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95Using a port range under a real server definition . . . . . . . . . . .96Using a port range under a virtual server definition . . . . . . . . .96Binding a port range for virtual ports to a real server . . . . . . . .96Defining port profile for port range. . . . . . . . . . . . . . . . . . . . . . . 97Displaying a list of port ranges . . . . . . . . . . . . . . . . . . . . . . . . . . 97

Multiple port binding. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98Direct binding of multiple ports . . . . . . . . . . . . . . . . . . . . . . . . .99Port aliases. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .101

Real server groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .105Defining a real server group . . . . . . . . . . . . . . . . . . . . . . . . . . .105Associating a real server with a real server group. . . . . . . . . .105Binding a real server group to a virtual server. . . . . . . . . . . . .106Showing real server groups. . . . . . . . . . . . . . . . . . . . . . . . . . . .106

Disabling or deleting VIPs and real ports . . . . . . . . . . . . . . . . . . . .107Disabling VIPs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107Disabling a real server. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107Disabling or re-enabling an application port . . . . . . . . . . . . . .107Globally disabling real and virtual ports. . . . . . . . . . . . . . . . . .108Deleting a VIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .108Enabling force-delete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .109Real server shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .110Port holddown timer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111

Hash-based SLB with server persistence . . . . . . . . . . . . . . . . . . . .114Persistent hash table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114Clear vs reassign mechanisms . . . . . . . . . . . . . . . . . . . . . . . . .114Enabling persistent hashing . . . . . . . . . . . . . . . . . . . . . . . . . . .115Enabling the clear-on-change mechanism. . . . . . . . . . . . . . . .115Enabling the reassign-on-change mechanism. . . . . . . . . . . . .116Configuring the reassign threshold and duration . . . . . . . . . .116Reassignment sequence and example . . . . . . . . . . . . . . . . . .117Keeping the persistent hash table unchanged . . . . . . . . . . . .119Real server failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .119Displaying persistent hash table entry and statistics . . . . . . .120Clearing the hit count for the persistent hash table . . . . . . . .121Clearing the persistent hash table . . . . . . . . . . . . . . . . . . . . . .121Reassigning a persistent hash table entry. . . . . . . . . . . . . . . .121Displaying hash bucket counters . . . . . . . . . . . . . . . . . . . . . . .122


SLB spoofing configuration and support. . . . . . . . . . . . . . . . . . . . .123

Policy-based SLB. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .123

Miscellaneous options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137Changing a real server’s IP address . . . . . . . . . . . . . . . . . . . . .137Adding a description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138Configuring a local or remote real server . . . . . . . . . . . . . . . . .138Defining the maximum number of connections . . . . . . . . . . .138Setting a logging threshold for connection rate. . . . . . . . . . . .139Configuring a TCP MSS value at the global level . . . . . . . . . . .141Configuring a TCP MSS value for a virtual server . . . . . . . . . .141Configuring a TCP MSS value at the virtual server port level .142Configuring a TCP MSS value at the TCP profile level . . . . . . .142Support for TCP Window Scale option in TCP header . . . . . . .142Binding a TCP profile to a virtual port and response rewrite policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143Configuring jumbo frame support. . . . . . . . . . . . . . . . . . . . . . .143Limiting the maximum number of TCP SYN requests . . . . . . .146Configuring the connection rate . . . . . . . . . . . . . . . . . . . . . . . .146Configuring hardware forwarding of pass-through traffic . . . .147Disabling port translation . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148Traffic distribution among BPs . . . . . . . . . . . . . . . . . . . . . . . . .149Including the server client port in hash calculations . . . . . . .149Sending ICMP Port Unreachable or Destination Unreachable messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150Sending a TCP RST to a client that requests unavailable applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150Sending a TCP RST when TCP session entry ages out . . . . . .151Disabling TCP RST message when a real server goes down during an open session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .151Disabling TCP RST message on maximum connections . . . . .152Decrement counters in deletion queue . . . . . . . . . . . . . . . . . .152Optimized fast-path SLB processing. . . . . . . . . . . . . . . . . . . . .152Configuring TCP fast aging . . . . . . . . . . . . . . . . . . . . . . . . . . . .155Server opt-enable-route recalculation . . . . . . . . . . . . . . . . . . .155Enabling use of the client MAC address. . . . . . . . . . . . . . . . . .156Enabling transparent VIP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .156Enabling SYN ACK threshold . . . . . . . . . . . . . . . . . . . . . . . . . . .156Replacing the source MAC address of the packet. . . . . . . . . .156Cloning real servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157Configuring a host range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157Unbinding all application ports from virtual servers . . . . . . . .158Identifying VIP port as TCP only or UDP only . . . . . . . . . . . . . .159Enabling fast aging for UDP sessions. . . . . . . . . . . . . . . . . . . .159Enabling normal UDP aging for DNS and RADIUS . . . . . . . . . .160Setting TCP and UDP ages for VIPs. . . . . . . . . . . . . . . . . . . . . .160Configuring session aging behavior . . . . . . . . . . . . . . . . . . . . .161Configuring DNS CPU-based throttling . . . . . . . . . . . . . . . . . . .161Configuring UDP DNS count connection . . . . . . . . . . . . . . . . .162Maximum server, port, and health check count . . . . . . . . . . .162


Policy-based routing for reverse SLB traffic . . . . . . . . . . . . . . .163Dedicated next hop per VIP for reverse SLB traffic . . . . . . . . .164Dynamic NAT for real servers using virtual server address . .165VIP route health injection . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165VIP RHI with dangling subnets . . . . . . . . . . . . . . . . . . . . . . . . .172VIP RHI and high availability topologies . . . . . . . . . . . . . . . . . .173

Application-specific SLB considerations . . . . . . . . . . . . . . . . . . . . .199RTSP server Load Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . .199Deletion of UDP data session along with TCP control session for RTSP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200TFTP load balancing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200

Show and debug commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200

SLB configuration examples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .200

Displaying the BP distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . .201

Windows Terminal Server with L7 persistence . . . . . . . . . . . . . . . .202Understanding windows terminal server . . . . . . . . . . . . . . . . .202Configuring Windows Terminal Server . . . . . . . . . . . . . . . . . . .204

Chapter 3 Stateless Server Load Balancing

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .205

Stateless TCP and UDP ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .205How the ServerIron ADX selects a real server for a stateless port. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .206Configuring the stateless hash table size . . . . . . . . . . . . . . . .207Configuring a stateless application port . . . . . . . . . . . . . . . . .207Fragmentation support in the stateless mode. . . . . . . . . . . . .209

Chapter 4 Health Checks

Health checks overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .211

Layer 3 health checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .211Disabling Layer 3 health checks . . . . . . . . . . . . . . . . . . . . . . . .212Modifying the ping interval and ping retries. . . . . . . . . . . . . . .213Server periodic-ARP enhancement. . . . . . . . . . . . . . . . . . . . . .213

Layer 4 health checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .213Performing Layer 4 UDP keepalive health checks for the DNS port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .215Server response threshold health check . . . . . . . . . . . . . . . . .216


Layer 7 health checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .218Application ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .219DNS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .220FTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .221HTTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .221Scripted (content verification for unknown ports) . . . . . . . . . .222IMAP4 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223LDAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223MMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .224NNTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .224PNM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .225POP3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .225RADIUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .226RTSP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229SMTP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229SSL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229Telnet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .231Configuring port-specific settings . . . . . . . . . . . . . . . . . . . . . . .231HTTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .232DNS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .233RADIUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .234LDAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .235Simple and complete SSL health checks. . . . . . . . . . . . . . . . .237Layer 7 health check for an unknown port . . . . . . . . . . . . . . .239

Server and application port states . . . . . . . . . . . . . . . . . . . . . . . . .240Server states . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .240Application port states. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241

Port profiles and attributes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .243Configuring a port profile. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .244Configuring port profile attributes . . . . . . . . . . . . . . . . . . . . . .245

Port policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .250Port policies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .250Configuring a port policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .250Binding the policy. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .252Configuring a keepalive interval under a port policy . . . . . . . .254Health check policy for VIP port . . . . . . . . . . . . . . . . . . . . . . . .255

Element health checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .255Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .255Configuring element-action expressions . . . . . . . . . . . . . . . . .255Attaching a health-check policy to an application port on a server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .264Displaying health-check policies and their status . . . . . . . . . .264Displaying health-check policy statistics . . . . . . . . . . . . . . . . .265Clearing health-check policy statistics . . . . . . . . . . . . . . . . . . .266

Health check with content match . . . . . . . . . . . . . . . . . . . . . . . . . .266Content match for HTTP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .266Content match for non-HTTP ports . . . . . . . . . . . . . . . . . . . . . .270Binary scripted health check. . . . . . . . . . . . . . . . . . . . . . . . . . .273


Boolean health checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 274Boolean health-check policies . . . . . . . . . . . . . . . . . . . . . . . . . 274Health-check policy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .275Configuring boolean health check . . . . . . . . . . . . . . . . . . . . . .275

Miscellaneous health check settings . . . . . . . . . . . . . . . . . . . . . . .277Basing an alias port’s health on the health of its master port277Basing a port’s health on the health of another port . . . . . . .278Reassign threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .279FastCache. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .280Globally disabling all health-check policies . . . . . . . . . . . . . . .281Health checking for real servers in other subnets. . . . . . . . . .281Best path to a remote server . . . . . . . . . . . . . . . . . . . . . . . . . .281Handling traffic initiated from remote server. . . . . . . . . . . . . .282Minimum healthy real servers under VIP port . . . . . . . . . . . . .283Server port bring-up retries . . . . . . . . . . . . . . . . . . . . . . . . . . . .283Layer 4 and Layer 7 port bring-up interval . . . . . . . . . . . . . . . .284Slow-start mechanism. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .284FIN close for server health check . . . . . . . . . . . . . . . . . . . . . . .292Health-check state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .292Enhanced server bringup . . . . . . . . . . . . . . . . . . . . . . . . . . . . .293Track-Port support under real server for health checks . . . . .293

Sample show commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .295Syslog for health status change . . . . . . . . . . . . . . . . . . . . . . . .295Health checks for firewall paths . . . . . . . . . . . . . . . . . . . . . . . .295Session table parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . .297Configuring TCP age. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .301Configuring UDP age . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .301Setting the clock scale. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .301Syslog for session table entries . . . . . . . . . . . . . . . . . . . . . . . .302

Chapter 5 Layer 7 Content Switching

Layer 7 content switching overview . . . . . . . . . . . . . . . . . . . . . . . . .305

Configuring Layer 7 content switching. . . . . . . . . . . . . . . . . . . . . . .306Enabling CSW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .306Specifying scan depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .306Enabling CSW load balance . . . . . . . . . . . . . . . . . . . . . . . . . . .307CSW rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .307CSW policies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .312Explanation of offsets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .328

Sample configurations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .329CSW topology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .330Request delete configuration . . . . . . . . . . . . . . . . . . . . . . . . . .331

Layer 7 content switching on HTTP response . . . . . . . . . . . . . . . . .334Response header rewrite . . . . . . . . . . . . . . . . . . . . . . . . . . . . .334Configuring HTTP header response rewrite . . . . . . . . . . . . . . .334Response body rewrite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .336Configuring HTTP body response rewrite . . . . . . . . . . . . . . . . .336


Using multiple cookies under virtual server port . . . . . . . . . . . . . .338Configuring multiple unique cookie insertion with cookie path. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .338Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .339

Server passive cookie persistence . . . . . . . . . . . . . . . . . . . . . . . . .341Configuring server passive cookie persistence . . . . . . . . . . . .342Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .344

Server and server port persistence with CSW nested rules. . . . . .344Configuring server and server port persistence with CSW nested rules. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .345Configuring persist on the nested rule . . . . . . . . . . . . . . . . . . .345Configuring persist on the real port . . . . . . . . . . . . . . . . . . . . .345

Displaying CSW information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .347Displaying header information . . . . . . . . . . . . . . . . . . . . . . . . .347Displaying CSW rule information. . . . . . . . . . . . . . . . . . . . . . . .348Displaying CSW policy information . . . . . . . . . . . . . . . . . . . . . .351Displaying the statistics for all HTTP content rewrites . . . . . .353Displaying Layer 7 switching statistics . . . . . . . . . . . . . . . . . . .354Displaying the hash-based server selection for CWS policies 355Displaying hash bucket counters . . . . . . . . . . . . . . . . . . . . . . .357

Usage guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .358Support for large GET requests. . . . . . . . . . . . . . . . . . . . . . . . .358

TCP/UDP content switching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .358Understanding TCP/UDP content switching. . . . . . . . . . . . . . .359Configuring TCP/UDP content switching . . . . . . . . . . . . . . . . .359TCP/UDP content switching commands. . . . . . . . . . . . . . . . . .363

Miscellaneous Layer 7 switching configurations . . . . . . . . . . . . . .366Changing the maximum number of concurrent Layer 7 connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .366Dropping requests on exceeding max-conn per real server . .366Cleaning up all hash buckets . . . . . . . . . . . . . . . . . . . . . . . . . .367Layer 7 content buffering options. . . . . . . . . . . . . . . . . . . . . . .367HTTP 1.1 support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .368Layer 7 CSW pseudo stack client-side retransmission handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .372Layer 7 CSW pseudo stack server-side TCP packet out-of-sequence handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374

Setting up SSL session ID switching . . . . . . . . . . . . . . . . . . . . . . . . 376

Command reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .380rewrite request-delete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .380rewrite request-insert . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .380rewrite request-replace . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .381

Chapter 6 High Availability

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .383Hot Standby HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .383Symmetric Active-Standby HA . . . . . . . . . . . . . . . . . . . . . . . . . .383Symmetric Active-Active HA. . . . . . . . . . . . . . . . . . . . . . . . . . . .383


Hot Standby HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .384Hot Standby HA protocol operations. . . . . . . . . . . . . . . . . . . . .384Configuring Standard Hot Standby HA . . . . . . . . . . . . . . . . . . .386Additional configuration variations . . . . . . . . . . . . . . . . . . . . . .391Sample configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .398

Symmetric Active-Standby HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . .399Configuring Symmetric Active-Standby HA . . . . . . . . . . . . . . . .399Additional configuration variations . . . . . . . . . . . . . . . . . . . . . .402

Symmetric Active-Active HA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .416Difference between Symmetric Active-Active HA versus Symmetric Active-Standby HA . . . . . . . . . . . . . . . . . . . . . . . . . .416Configuring Symmetric Active-Active HA. . . . . . . . . . . . . . . . . . 417

Manual triggering of symmetric HA failover with VRRP-E. . . . . . . . 417Configuring manual HA failover. . . . . . . . . . . . . . . . . . . . . . . . .418Upgrade process for the symmetric HA setup using VRRP-E .418Displaying the current VRRP-E priority status . . . . . . . . . . . . .420

Orchestrating seamless HA failover using VRRP-E pool . . . . . . . . .421Configuring VRRP-E pools . . . . . . . . . . . . . . . . . . . . . . . . . . . . .423Guidelines for configuring VRRP-E pools . . . . . . . . . . . . . . . . .423

Maintaining traffic symmetry by adjusting OSPF cost during HA and VRRP-E switchover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .424

Configuring OSPF cost adjustment during HA and VRRP-E failover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .425

OSPF and route-map configuration . . . . . . . . . . . . . . . . . . . . .426

Additional variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .426Multiple high availability SLB pairs in the same VLAN . . . . . .426NAT in HA environments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .427IP NAT session synchronization in HA configurations . . . . . . .433Shareable source NAT for high availability . . . . . . . . . . . . . . . .433Configuring server accelerated-fin-sync command . . . . . . . . .438Configuring synchronization with HA . . . . . . . . . . . . . . . . . . . .439

Miscellaneous options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .439Displaying VIP owner in HA setup . . . . . . . . . . . . . . . . . . . . . . .439Identifying the ports attached to a router . . . . . . . . . . . . . . . .439Setting VIP failback delay . . . . . . . . . . . . . . . . . . . . . . . . . . . . .439

Chapter 7 IPv6 Support for Server Load Balancing

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .441

Defining IPv6 real servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .441

Defining IPv6 virtual servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .442

Defining IPv4 real servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .442

Defining IPv4 virtual servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .442

Defining port characteristics using port profile . . . . . . . . . . . . . . .442

Defining IP routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .442

VLAN, tagging and trunk definitions . . . . . . . . . . . . . . . . . . . . . . . .443


VRRP-E and VIP group definitions . . . . . . . . . . . . . . . . . . . . . . . . . .443

Miscellaneous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .444

Saving the configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .444

IPv6 to IPv4 gateway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .444Features not supported with the IPv6 to IPv4 gateway . . . . . .446Packet fragmentation with the IPv6 to IPv4 gateway . . . . . . .446ICMP packet processing for the IPv6 to IPv4 gateway. . . . . . .447IPv6 to IPv4 gateway high availability support . . . . . . . . . . . . .448Configuring the IPv6 to IPv4 gateway . . . . . . . . . . . . . . . . . . . .449Displaying IPv6 to IPv4 gateway information . . . . . . . . . . . . . .450

IPv4 to IPv6 gateway . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .451Configuring the IPv6 prefix . . . . . . . . . . . . . . . . . . . . . . . . . . . .452Features not supported with the IPv4 to IPv6 gateway . . . . . .453Packet fragmentation with the IPv4 to IPv6 gateway . . . . . . .453ICMP packet processing for the IPv4 to IPv6 gateway. . . . . . .454IPv4 to IPv6 gateway high availability support . . . . . . . . . . . . .455Configuring the IPv4 to IPv6 gateway . . . . . . . . . . . . . . . . . . . .456Displaying IPv4 to IPv6 gateway information . . . . . . . . . . . . . .456

Appendix A Server-specific Loopback Configurations

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .457

Solaris . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .457

Linux. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .457

Windows NT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .458Manual installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .458Unattended installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .458Deleting the unwanted routes. . . . . . . . . . . . . . . . . . . . . . . . . .459

Appendix B Basic Configuration Example

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .463

Both ServerIron ADX sites working in primary mode . . . . . . . . . . .464Site 1 configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .465Site 2 configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .470

Site-1 ServerIron ADX in primary mode and site-2 in backup mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 476

Site 1 configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .477Site 2 configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .482

Appendix C SLB Show and Debug Commands

Using show source-ipsource-ip [ real-server-ip | all] . . . . . . . . . . .491

Using the show session all command . . . . . . . . . . . . . . . . . . . . . . .492

Using the source-ip-debug command . . . . . . . . . . . . . . . . . . . . . . .493


Using the debug filter command . . . . . . . . . . . . . . . . . . . . . . . . . . .493Using the packet capture utility . . . . . . . . . . . . . . . . . . . . . . . .493"debug filter" example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .500Helpful tips . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .504

Emulating tcpdump using the debug filter . . . . . . . . . . . . . . . . . . .504

Displaying global Layer 4 ServerIron ADX configuration. . . . . . . . .505

Displaying real server information and statistics . . . . . . . . . . . . . .508Using the show server real command . . . . . . . . . . . . . . . . . . .508Using the show server real detail command . . . . . . . . . . . . . .511Displaying real server keepalive statistics . . . . . . . . . . . . . . . .514Displaying real server connections per second statistics . . . .514

Displaying virtual server information and statistics . . . . . . . . . . . .515

Displaying a list of failed servers . . . . . . . . . . . . . . . . . . . . . . . . . . .518

Displaying a list of failed ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . .519

Displaying port-binding information. . . . . . . . . . . . . . . . . . . . . . . . .519Using the show server bind command . . . . . . . . . . . . . . . . . . .519Using the show server session command . . . . . . . . . . . . . . . .520

Displaying packet traffic statistics . . . . . . . . . . . . . . . . . . . . . . . . . .522

Displaying configuration information. . . . . . . . . . . . . . . . . . . . . . . .524Showing aggregate health of tracked ports . . . . . . . . . . . . . . .525Auto repeat of show command output . . . . . . . . . . . . . . . . . . .526Clearing all session table entries . . . . . . . . . . . . . . . . . . . . . . .526Simplified Clearing of Server Sessions. . . . . . . . . . . . . . . . . . .528Clearing the connections counter. . . . . . . . . . . . . . . . . . . . . . .528

Appendix D SLB Configuration Examples

Web hosting with multiple virtual servers mapped to one real server . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .529

Multiple port binding using port aliases . . . . . . . . . . . . . . . . . . . . .530

TCP/UDP application groups . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .531

Web hosting with ServerIron ADX and real servers in different subnets. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .534

SLB with ServerIron running Layer 3 image . . . . . . . . . . . . . . . . . .536

Basic SLB with multiple subnets and multiple virtual routing interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .539

Appendix E Acknowledgements

OpenSSL license . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .543

Cryptographic software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .544

Original SSLeay License . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .544


Preface

Document conventions

The document conventions describe text formatting conventions, command syntax conventions, and important notice formats used in Foundry technical documentation.

Text formatting conventionsText formatting conventions such as boldface, italic, or Courier may be used in the flow of the text to highlight specific words or phrases.

Format Description

bold text Identifies command names

Identifies keywords

Identifies the names of user-manipulated GUI elements

Identifies text to enter at the GUI or CLI

italic text Provides emphasis

Identifies variables and modifiers

Identifies paths and Internet addresses

Identifies document titles

Courier font Identifies CLI output

Identifies command syntax examples


Command syntax conventionsBold and italic text identify command syntax components. Delimiters and operators define groupings of parameters and their logical relationships.

Notes, cautions, and warningsThe following notices and statements may be used in this document. They are listed below in order of increasing severity of potential hazards.

NOTEA note provides a tip, guidance or advice, emphasizes important information, or provides a reference to related information.

ATTENTIONAn Attention statement indicates a stronger note, for example, to alert you when traffic might be interrupted or the device might reboot.

CAUTION

A Caution statement alerts you to situations that can be potentially hazardous to you or cause damage to hardware, firmware, software, or data.

DANGER

A Danger statement indicates conditions or situations that can be potentially lethal or extremely hazardous to you. Safety labels are also attached directly to products to warn of these conditions or situations.

Convention Description

bold text Identifies command names, keywords, and command options.

italic text Identifies a variable.

[ ] Syntax components displayed within square brackets are optional.

Default responses to system prompts are enclosed in square brackets.

{ x | y |z } A choice of required parameters is enclosed in curly braces separated byvertical bars. You must select one of the options.

x | y A vertical bar separates mutually exclusive elements.

< > Nonprinting characters, for example, passwords, are enclosed in angle brackets.

... Repeat the previous element. For example, member [member...].

\ Indicates a “soft” line break in command examples. If a backslash separates two lines of a command input, enter the entire command at the prompt without the backslash.


Brocade resources

Visit the Brocade website to locate related documentation for your product and additional Brocade resources.

You can download additional publications supporting your product at www.brocade.com. Select the Brocade Products tab to locate your product, then click the Brocade product name or image to open the individual product page. The user manuals are available in the resources module at the bottom of the page under the Documentation category.

To get up-to-the-minute information on Brocade products and resources, go to MyBrocade. You can register at no cost to obtain a user ID and password.

Release notes are available on MyBrocade under Product Downloads.

White papers, online demonstrations, and data sheets are available through the Brocade website.

Select Application Delivery Switches on this page to navigate to the relevant product information.

Contacting Brocade Technical Support

As a Brocade customer, you can contact Brocade Technical Support 24x7 online, by telephone, or by e-mail. Brocade OEM customers contact their OEM/Solutions provider.

Brocade customersFor product support information and the latest information on contacting the Technical Assistance Center, go to http://www.brocade.com/services-support/index.html

If you have purchased Brocade product support directly from Brocade, use one of the following methods to contact the Brocade Technical Assistance Center 24x7.

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Preferred method of contact for non-urgent issues:

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ServerIron ADX Server Load Balancing Guide53-1003452-01

Chapter

1
Features and Enhancements
Release 12.5.02

Enhancement Description Documented in the following books

Increase of GSLB zones

The ServerIron ADX supports a maximum of 4,000 DNS zones, hosts, and applications, and a maximum of 8,000 DNS IP addresses.

Book: ServerIron ADX Global Server Load Balancing Guide

Secure GSLB using OpenSSL

The ServerIron ADX supports a maximum of 2,048 bit SSL key size from the previous maximum of 1,024 bit key size.

Book: ServerIron ADX Global Server Load Balancing Guide

OpenScript APIs for parsing SSL certificates

The OpenScript module includes a new set of APIs that can provide insights into an SSL certificate used in establishing a secure connection between a client and the ServerIron ADX.

Book: ServerIron ADX OpenScript API Guide

OpenScript load balancing based on HTTP payload

You can define specific OpenScript actions, such as forward, log, reset, based on specific information available in the HTTP payload.

Book: ServerIron ADX OpenScript API Guide

TLS 1.1 and TLS 1.2 The ServerIron ADX supports protocol versions TLS 1.1 and TLS 1.2.

Book: ServerIron ADX Security Guide

IPv6 Clients support for maximum concurrent connection

The ServerIron ADX supports IPv6 clients for the maximum concurrent connection per client feature.

Book: ServerIron ADX Security Guide

Changing the name of a virtual server

The new name command allows you to change the name to a virtual server without having to delete the complete virtual server configuration.

Book: ServerIron ADX Server Load Balancing Guide

Health check: Layer 7 health check for RADIUS accounting

The ServerIron ADX supports RADIUS accounting health checks.


Health check: SSL health check cipher suites

This ServerIron ADX supports the following cipher suites as part of the SSL health checks in simple and complete SSL health check modes.• TLS_RSA_WITH_AES_256_CBC_SHA - AES cipher

algorithm using 256 bit key size• TLS_RSA_WITH_AES_128_CBC_SHA - AES cipher

algorithm using 128 bit key size


1

Release 12.5.01a1

Release 12.5.01a

High Availability (HA): Increase the number of symmetric HA groups

The number of symmetric HA groupshas increased to 255. Book: ServerIron ADX Server Load Balancing Guide

High Availability (HA): Simplified symmetric HA failover

The new vrrpe standby command forces an active ServerIron ADX to failover to its backup ServerIron ADX in a symmetric setup with VRRP-E. Prior to 12.5.02 release, the ServerIron ADX deployed in a symmetric HA mode, cannot be upgraded without configuration changes or disabling of ports.



IPv6 Host-Range The host-range definition for servers is now extended tosupport IPv6 servers.

Book: ServerIron ADX Server Load Balancing Guide Chapter: Server Load BalancingSection: Configuring IPv6 host-range

Simplified Clearing of Server Sessions

The clear server command is enhanced with additional options to simplify clearing of server-bound sessions.

Book: ServerIron ADX Server Load Balancing Guide Chapter: SLB Show and Debug CommandsSection: Displaying configuration information

Pass-through flow management

Stateful devices such as firewalls and Deep Packet Inspection (DPI) devices require visibility into both forward and reverse traffic flows to process them appropriately. These devices fail to function if the network handles traffic asymmetrically.Using the pass-through flow management feature, the ServerIron ADX supports stateful handling of network flows while ensuring that it sends the reverse traffic to the same device that previously forwarded it.Pass-through flow management is a standalone feature and is applicable for TCP and UDP traffic flows only.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: Pass-Through Flow Management

Certificate Verification Using Online Certificate Status Protocol (OCSP)

OCSP (Online Certificate Status Protocol) is one of two schemes used for obtaining revocation status of an SSL certificate. The other method is known as Certificate Revocation List (CRL). The CRL method involves frequent download of the CRL list in order to maximize use of the most current information. OCSP overcomes this chief limitation of the CRL. In addition, since the OCSP response contains less information than a typical CRL, OCSP utilizes networks and client resources more efficiently. The ServerIron ADX previously supported only the CRL method. It now also supports OCSP.

Book: ServerIron ADX Security Guide Chapter: Secure Socket Layer (SSL) AccelerationSection: Creating a certificate revocation list


Release 12.5.01a 1

Increasing TRL Limits for IPv4 and IPv6

The TRL limit is now configurable under the ServerIron ADX system parameters for both IPv4 and IPv6. With this feature, you can configure a TRL limit for IPv4 from 1000 to 25000 and for IPv6 from 1000 to 15000, based on the requirement. If you want to alter the default TRL limit (15000), you must reload the ServerIron ADX after saving the configuration.

Book: ServerIron ADX Security Guide Chapter: Network SecuritySection: Configuring transaction rate limit for all rules under all policies

Prioritizing critical IPC traffic

The IPC traffic between the MP and BP is critical as it is used to ensure the health of the BP and synchronize information from the MP to the BP. The ServerIron ADX in this release reserves dedicated bandwidth for uninterrupted processing of IPC traffic.

Book: ServerIron ADX Security Guide Chapter: Network SecuritySection: Prioritization of Critical System Traffic and Management Traffic

Securing Management Processor through Traffic Rate Limiting

In this release, ICMP and SNMP attacks to the management processor can be thwarted by rate limiting this traffic in the hardware. Administrators can couple this enhancement with other security features on the ServerIron ADX to tightly secure their application server farm.

Book: ServerIron ADX Security Guide Chapter: Network SecuritySection: Securing Management Processor through Traffic Rate Limiting

VIP Level Priority Threshold

The ServerIron ADX enables administrators to assign varying priority levels to different service VIPs. The assignments can be done based on the relative importance of these applications to business operations.

Book: ServerIron ADX Security Guide Chapter: Network SecuritySection: Application Traffic Prioritization

VIP Maximum Connection Rate

The VIP maximum connection rate feature allows you to specify the maximum-allowed connection rate for respective virtual servers, thus providing traffic rate limiting at the VIP level.

Book: ServerIron ADX Security Guide Chapter: Network SecuritySection: Prioritization of Critical System Traffic and Management Traffic

Ability to assign IPV6 RADIUS address

The ServerIron ADX allows you to assign an IPV6 RADIUS address.

Book: ServerIron ADX Administration Guide Chapter: Secure Access ManagementSection: Identifying the RADIUS server using its IPv6 address

Dedicated Default route for management

The ServerIron ADX allows you to define a dedicated default route for management purposes in addition to specifying a general-purpose default route for processing data plane traffic.

Book: ServerIron ADX Administration Guide Chapter: ServerIron System ManagementSection: Configuring a dedicated default route for management


Release 12.5.011

Release 12.5.01

Disabling of SNMP v1 The SNMP version 1 has enjoyed unparalleled success as an extremely useful management tool. However, it has certain shortcomings, especially its lack of strongsecurity. In this release, administrators can disable SNMP v1 and utilize higher versions of SNMP in a highly secure environment.

Book: ServerIron ADX Administration Guide Chapter: ServerIron System ManagementSection: Disabling SNMP versions

Support for IPv6 sFlow

Support for IPv6 sFlow enables administrators to identify their sFlow server and RADIUS and TACACS+ server destinations using an IPv6 address.

Book: ServerIron ADX Switching and Routing Guide Chapter: sFlowSection: Specifying the collector


IPv6 Source NAT ACL support

When an access-list (ACL) is applied to the source-NAT configuration under real server, then the source-NAT is restricted to traffic originated from IPv4 addresses identified using the ACL. With this software release, the source-NAT ACL feature is enhanced to support source-NAT for both IPv4 and IPv6 addresses.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: Source NAT, IPv6 Source-Nat ACL support

Source NAT, interface, and IPv6 address CAM optimization

A ServerIron ADX running multitenancy mode is now optimized by default to reduce the number of CAM entries created for source NAT, interface, and source IPv6 addresses. In earlier releases, the CAM entries are quickly exhausted because the number of CAM entries per address are multiplied by the number of addresses per tenant and the number of tenants. If required, you can disable this optimization.

Book: ServerIron ADX Multitenancy GuideChapter: System Maintenance and MonitoringSection: Disabling source NAT, interface, and source IPv6 address CAM optimization in multitenancy mode

DNS TTL modification under a GSLB host-level policy

DNS TTL modification is now configurable in a host-level policy that you apply to specified hosts within GSLB domains. Previously, you could only configure the DNS TTL in the GSLB global policy that applied to all hosts configured under a GSLB zone.

Book: ServerIron ADX Global Server Load Balancing GuideChapter: Global Server Load BalancingSection: Configuring the parameters for the host-level policy (Changing the TTL for DNS records)


Release 12.5.01 1

Increased scale of distributed GSLB health checks

In release 12.4.0g and later, each site ServerIron ADX has the ability to send a maximum of 30 ports per VIP address in the VIP address list message. Previously, each site ServerIron ADX could send a maximum of 10 ports for each VIP address.

Book: ServerIron ADX Global Server Load Balancing GuideChapter: Global Server Load BalancingSection: Configuring the maximum ports per VIP address in a VIP address list message

Selection metric counters for real servers

In release 12.4.0g and later, the ServerIron ADX can display the selection metric counter for real servers or sites that are hosted on non-Brocade application delivery controllers when you use the show gslb dns detail command.

Book: ServerIron ADX Global Server Load Balancing GuideChapter: Global Server Load BalancingSection: Displaying metric informationChapter: Global Server Load Balancing for IPv6Section: Displaying detailed DNS information

Preserving IPv6 SLB path optimization with GSLB

The ServerIron ADX now provides an optional configuration that preserves IPv6 SLB path optimization even after the enabling of GSLB. By default, IPv6 SLB path optimization is disabled. You can enable this feature before or after you enable GSLB. If you do not enable this feature, the ADX directs all IPv6 SLB traffic to the non-optimized path. In earlier releases, the ServerIron ADX disabled optimization of IPv6 SLB processing when you enabled GSLB.

Book: ServerIron ADX Global Server Load Balancing GuideChapter: Global Server Load Balancing for IPv6Section: Enabling the optimized IPv6 path for GSLB IPv6 optimization

New Content Inspection API for OpenScript

The new OS_PAYLOAD_INSPECT module includes APIs to inspect unlimited amounts of streaming payload content from either the client or server side and, when required, to change the content. These APIs can perform the following functions:• Match and replace text strings, binary signatures, and

encoded patterns in HTTP. These APIs also allow you to define the match criteria for the length of the text string or binary pattern.

• Generate match events that can be used as triggers for logging, filtering, and carrying out security policies.

Book: ServerIron ADX OpenScript API GuideChapter: Content Inspection API Reference

Book: ServerIron ADX OpenScript Programmer’s GuideChapter: OpenScript FundamentalsSection: Structure of a ServerIron ADX Perl scriptChapter: Managing Scripts on a ServerIron ADXSection: Displaying script information

VRRP-E pool A VRRP-E pool is a group to which you can add all VRRP-E instances configured within a ServerIron ADX device that is part of an HA pair. When the ADX devices configured in an HA pair are subjected to HA failovers, pooling the VRRP-E instances prevents traffic loss and maintains predictable traffic flow.

Book: ServerIron ADX Switch Router GuideChapter: Configuring VRRP and VRRP-ESection: VRRP-E pool


Release 12.5.011

OSPF cost change followed by VRRP-E status change

The OSPF cost change functionality applies to an HA topology in which the server side of ServerIron ADX devices is configured with VRRP-E and the router side of the ServerIron ADX devices is configured with OSPF. OSPF tracks the mastership of the server-side VRRP-E VRID instances and dynamically controls the cost of the redistributed static VIP routes, advertised to the upstream router.

Book: ServerIron ADX Switch Router GuideChapter: Configuring VRRP and VRRP-ESection: OSPF cost change followed by VRRP-E status change

Configuration synchronization feature enhancements

The configuration synchronization feature:• Sends a message to the sender device when the

commands are not executed on the receiver device.• Prints error messages when the configuration is not

synchronised properly.• Sends messages if incremental synchronization

commands are not successfully executed.

Book: ServerIron ADX Administration GuideChapter: Configuration Synchronization Section: Debugging the configuration synchronization and Monitoring the progress of configuration synchronization

Tie up of configuration synchronization with High Availability

Configuration synchronization is tied to the existing High Availability (HA) modes so that the active device is always the configuration synchronization sender device and the standby device is always the receiver device.

Book: ServerIron ADX Administration GuideChapter: Configuration Synchronization Section: Configuration synchronization between the HA pairs


Release 12.5.00 1

Release 12.5.00


Support for Multitenant Cloud Environments

The ServerIron ADX device can now be deployed in a multitenant mode allowing the provisioning and management of multiple virtualized instances of the ADX on the same device. In this mode of operation, administrators of hosted or private clouds can configure and manage the ADX device while delegating the administration of each hosted ADX instance to an individual tenant. In this context, the ServerIron ADX device administrator can provide each tenant with dedicated resources and a completely isolated network, while providing control of application traffic directly to that tenant.

Book: ServerIron ADX Multitenancy Guide.

Increased 2048 Bit SSL Performance on Modular ADX Platforms

Increased 2048 Bit SSL Performance on Modular ADX PlatformsTo assist customers in the offloading of 2048 bit SSL encryption/decryption, release 12.5 includes significant enhancements to 2048-bit SSL Transactions per Second (TPS) - nearly doubling the performance compared to previous releases. This performance improvement is made possible through a combination of software and hardware improvements including updates to the SI-MM-SSL and SI-AEM-SSL expansion modules for the SI-4000 and SI-10000 systems.

Book: ServerIron ADX Installation Guide.Chapter: Product OverviewSection: SSL Expansion ModuleChapter: Installing ServerIron ADXSection: Installing an SSL Expansion module onto a management module

Enhancements to Configuration Synchronization

Book: ServerIron ADX Administration Guide.Chapter: Configuration Synchronization


Release 12.5.001

Enhanced Web-based GUI

The Brocade ADX Web interface now includes the following additional capabilities.• Multitenancy

• Enhanced views for administrators deploying the ADX in Multitenancy mode

• Dashboard/Monitoring improvements• Display of historical statistics (up to 24 hours)

that can be exported from the device• Statistics for IPv6 Interface and Neighbor • Statistics for Routing Protocols - BGP, OSPF• Monitoring enhancements for Virtual Server/

Real Server including additional fields for Rx kbps, Tx kbps, and Connections/sec

• Configuration Improvements• Configuration wizard for simplified deployment of

server load balancing• Support for configuration synchronization• Support for device management - SNMP, Telnet,

SSH • Support for RADIUS/ TACACS • Support for SYN Proxy

• Maintenance improvements• Packet capture utility for improved visibility into

traffic patterns• Context-sensitive help

Book: ServerIron ADX Graphical User Interface Guide

New XML APIs to support enhanced third party management integration

This release includes XML API enhancements to the following ADX functional areas:• Multitenancy

• Device administration• Tenant provisioning • Tenant configuration, management and

monitoring• Device Management

• Packet capture• Historical statistics and export• Configuration synchronization• Device management - SNMP, Telnet, SSH RADIUS/ TACACS

• Load Balancing• Enhancements to VIP/real server statistics

(throughput and connections/sec)• Network management

• Routing configuration and statistics (BGP, OSPF and IPv6)

• VRRP/e statistics• Security/Protection

• SYN Proxy

Book: ServerIron ADX XML API Programmers Guide


Release 12.4.00a 1

Release 12.4.00a


Additional statistics for Real and Virtual Servers

With this release, ServerIron ADX now provides throughput and connections per second metrics for both real and virtual servers (VIPs) along with supporting SNMP traps.

Book: ServerIron ADX Server Load Balancing GuideAppendix: SLB Show and Debug CommandsBook: IronWare MIB Reference.Chapter: ServerIron ADX SLB MIBSection: Real Server Statistics Table and Virtual Server Statistics Table

Intelligent Re-use of Newly-available Cache Servers

Starting with release 12.4.00a, the Brocade ServerIron ADX is powered with a new intelligent algorithm that minimizes the impact on traffic persistency while allowing seamless addition of newly-available cache servers.

Book: ServerIron ADX Advanced Server Load Balancing Guide.Chapter: Transparent Cache SwitchingSection: Resilient Hashing for Maximum Cache Persistence

SNMP-based Health Monitoring with Layer-7 TCS Policy:

The Brocade ServerIron ADX already supported an advanced SNMP-based health monitoring system for checking real-time state of Blue Coat CacheFlow servers. These same capabilities have been extended in this release to an environment where a Brocade ServerIron ADX is enabled for cache selection through application-specific Layer-7 rules.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: Transparent Cache SwitchingSection: Traffic distribution based on cache server capacity

Bypassing of Embedded Protocols

For network environments where non-HTTP protocols such as FTP and RTSP are masquerading over port HTTP, the Brocade ServerIron ADX provides network administrator additional flexibility to bypass such embedded traffic to the Internet instead of forwarding to cache servers.

Book: ServerIron ADX Advanced Server Load Balancing Guide.Chapter: Transparent Cache SwitchingSection: Bypassing embedded protocols.

Brocade OpenScript API Enhancements

The OpenScript dataplane scripting engine now supports the inspection and rewrite of the HTTP body and has been extended to include API support for IP, UDP and TCP based traffic

Book: ServerIron ADX OpenScript Programmer’s GuideBook: ServerIron ADX OpenScript API Guide


Release 12.4.01

Release 12.4.0

Brocade OpenScript SNMP Trap Enhancement

An SNMP trap has been added to provide notification when an OpenScript event occurs.

Book: IronWare MIB ReferenceChapter: Traps and Objects to Enable TrapsSection: SLB Real Server connection traps

Brocade OpenScript GUI Enhancement

With this release, the ServerIron ADX GUI now supports the ability to upload/download scripts to and from the local client.

Book: ServerIron ADXGraphical User Interface GuideChapter: Traffic SettingsSection: Uploading and downloading scripts


Hash-based persistence in TCS for SSL traffic

In previous releases, SSL traffic could only be distributed among servers in a cache group using the least connection method. With this release, SSL traffic uses a hashing algorithm based on source and destination IP addresses as its default distribution method. Additionally, you can now use a command to toggle the traffic distribution method between the least connection method and the hashing algorithm for any protocol.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: Transparent Cache SwitchingSection: Assigning web cache servers to cache groupsSection: Selecting a method for server selection within a cache group

Enabling a ServerIron ADX SSL to respond with renegotiation headers

This feature allows you to configure a ServerIron ADX to respond with renegotiation headers that tell browsers that the ServerIron ADX handles renegotiation messages correctly and stops them from sending a false message that the ServerIron ADX is vulnerable to renegotiation attacks.

Book: ServerIron ADX Security Guide.Chapter: Secure Socket Layer (SSL)Section: Enabling a ServerIron ADX SSL to respond with renegotiation headers.

HTTP 1.1 support for content aware cache switching

With this release, keep alive mode for TCS is enabled by default and TCP offload is supported to allow the ServerIron ADX to fully support HTTP 1.1.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: Transparent Cache SwitchingSection: HTTP 1.1 support for TCS CSW

TCS for IPv6 The Transparent Cache Switching feature has been updated in this release to support IPv6.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: Transparent Cache Switching


Release 12.4.0 1

IPv6 GSLB This feature implements GSLB for IPv6 for host name in the DNS Cache Proxy + DNS override mode. Ins this mode, the IPv6 addresses for hosts are configured on the ServerIron ADX GSLB controller. It acts as the authoritative DNS server the configured zones. It intercepts DNS queries and if these are AAAA queries for configured hosts, the ServerIron ADX generates the DNS response by applying configured GLSB policies on the IPv6 list configured for the hostname.

Book: ServerIron ADX Global Server Load Balancing GuideChapter: Global Server Load Balancing

Authenticating RBM through a AAA server

Beginning with this release, you can authenticate a user for Role Based Management access through a AAA (Radius or TACACS+) server.

Book: ServerIron ADX Administration Guide.Chapter: Role Based ManagementSection: Integrating RBM with RADIUS and TACACS+.

IPv4 to IPv6 Gateway Beginning with software release 12.4, the ServerIron ADX allows an IPv4 client to send and receive packets to and from an IPv6 server.

Book: ServerIron ADX Server Load Balancing GuideChapter: IPv6 Support for Server Load BalancingSection: “IPv4 to IPv6 gateway”

Direct Multiple Port Binding

ServerIron ADX now enables real server port to be directly bound to multiple virtual ports. Formerly, a real server port could be bound to multiple virtual ports only by means of port aliases.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Direct binding of multiple ports”

Real Server Groups Real server groups facilitate the definition of multiple port bindings and reduce the size of configurations by enabling you to associate multiple real servers to a real server group and then binding that real server group to one or more virtual servers.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Real server groups”

IPv6 L3 Direct Server Return

Beginning with this release ServerIron ADX supports TOS marking and L3 Direct Server Return health checks on IPv6 servers.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “TOS marking of SLB and health check packets”

Enhanced LDAP-LDAPS Health Check

Beginning with this release ServerIron ADX supports authenticated bind operations with LDAP and LDAPS servers and searches of the directory; ServerIron ADX marks the port as active only after a successful authenticated bind and search operation.

Book: ServerIron ADX Server Load Balancing GuideChapter: Health Check Section: “LDAP”

Health Check Response Threshold

The ServerIron ADX compares the calculated response time and compares that with the configured response threshold. If the calculated response time is greater than the configured response threshold, the port is marked down.

Book: ServerIron ADX Server Load Balancing GuideChapter: Health Check Section: “Server response threshold health check”


Release 12.4.01

IPsec for OSPFv3 With this release, ServerIron ADX supports the implementation of Internet Protocol Security (IPsec) for securing OSPFv3 traffic.

Book: ServerIron ADX Switch and Router GuideChapter: Configuring OSPFv3Section: IPsec for OSPFv3

IPv6 IS-IS Multi-Topology

With this release, ServerIron ADX supports IPv6 IS-IS Multi-Topology.

Book: ServerIron ADX Switch and Router GuideChapter: Configuring IPv6 IS-ISSection: IPv6 IS-IS Multi-Topology.

IPv6 Element Heath Check

Beginning with this release the ServerIron ADX supports Element health checks for IPv6 addresses.

Book: ServerIron ADX Server Load Balancing GuideChapter: Health ChecksSection: “Specifying the IP address and application port parameters”

Per-VIP RHI BInding Threshold

Previous releases allowed you to define the percentage of bound real server ports that must be healthy in order to consider the VIP port healthy. With this release, that percentage can be configured per-VIP.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Defining the health of a VIP port”

IPv6 FWLB With this release ServerIron ADX supports IPv6 with Firewall Load Balancing

Book: ServerIron ADX Firewall Load Balancing Guide

IPv6 jumbo MTU support

With this release you can configure a ServerIron ADX to support an IPv6 MTU size up to 9234 Bytes. IPv6 MTU can be set globally or per virtual interface.

Book: ServerIron ADX Server Load Balancing GuideChapter: Configuring IPv6 AddressingSection: Enabling IPv6 jumbo MTU supportBook: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Configuring jumbo frame support”


Release 12.4.0 1

Layer 7 Performance enhancement (backward compatibility)

The following behavior has changed to support Layer 7 performance improvement and provide backward compatibility. In version 12.4.00, if the next request from the same client connection is forwarded within the same server group, the ServerIron ADX will not run the server load balance predictor algorithm to choose a new server. It will just use the same real server for the current request. If the next request goes to a different server group, the ServerIron ADX will follow the current code behavior to perform server section. A command is provided that sets the behavior back to pre-12.4.00 behavior which enables use of a load balancing predictor

Book: ServerIron ADX Server Load Balancing GuideChapter: Layer 7 Content SwitchingSection: “Enabling CSW load balance”

Setting a logging threshold for connection rate

With this release, you can set a threshold on the ServerIron ADX to send a log message for the following connection rates: the maximum number of sessions the ServerIron ADX maintains in its session table for all barrel processors or a real server pool, the maximum number of new TCP connections per-second allowed on a real server and the maximum number of UDP connections per-second allowed on a real server.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Setting a logging threshold for connection rate”

Assigning a virtual VRRP-E address in theIPv6 format

Beginning with release 12.4.00, a global unicast IPv6 address can be configured as the VRIDaddress in VRRP-E. In previous releases, only link-local IPV6 addresses were allowed to beconfigured as IP address of the VRID.

Book: ServerIron ADX Switch and Router GuideChapter: Configuring VRRP-E for IPv6Section: “Assigning virtual VRRP-E address in IPv6 format”

ServerIron ADX OpenScript

Brocade OpenScript provides data plane scripting functionality to manipulate traffic inreal-time.

Book: ServerIron ADX OpenScript Programmer’s GuideBook: ServerIron ADX OpenScript API Guide

SOAP/XML Application Programmatic Interface (API)

New APIs have been added to increase functionality of the SOAP/XML Application Programmatic Interface (API)



Release 12.3.011

Release 12.3.01


NAT64 Gateway Starting with software release 12.3.01, the Brocade ServerIron ADX adds support for standards-based NAT64 gateway capabilities to provide inter-operation between IPv4 networks and IPv6 networks. In NAT64 gateway mode, the ServerIron ADX enables IPv6-only clients to connect to IPv4-only infrastructure and also maintains state information for translated flows. It also preserves the originating client IPv6 address by inserting it into a custom HTTP header. In addition, the ServerIron ADX enables communication from IPv4-only devices to IPv6-only resources in stateless mode, and it also allows for peer-to-peer communication where traffic can originate from an end-node running either of the two protocols.

Book: ServerIron ADX NAT64 Configuration Guide

DNS Attack Protection With this release, the ServerIron ADX also provides protection against distributed denial of service attacks such as DNS amplification attacks. A ServerIron ADX can be configured to forward, drop or rate limit DNS traffic based on DNS query name, DNS query type, and DNS recursion flag.

Book: ServerIron ADX Security Guide.Chapter: Network SecuritySection: DNS Attack Protection

Multiprotocol BGP support

With software release 12.3.01, the ServerIron ADX extends support for Border Gateway routing Protocol (BGP) for IPv4 and IPv6 network prefixes. This gives network administrators added flexibility for deploying the Brocade ADX in environments running RIP, OSPFv2, OSPFv3, IS-IS and BGP routing protocols. The support is also extended to VIP route health injection with BGP in order to provide disaster recovery in the event of data center/site failure.

Book: ServerIron ADX Switch and Router Guide.Chapter: Configuring BGP4 (IPv4)Chapter: Configuring BGP4+

Hardware switching for unknown unicast traffic

Starting with release 12.3.01, the ServerIron ADX protects application delivery infrastructures from flood of unknown Unicast packets by processing them in hardware.

Book: ServerIron ADX Switch and Router Guide.Chapter: Configuring Basic FeaturesSection: Enabling hardware switching for unknown unicast traffic

IPv6 ACL hardware processing

IPv6 access control lists (ACLs) are now processed in hardware for high-performance and secure application delivery. The section referenced here describes how to switch ACL processing for legacy performance.

Book: ServerIron ADX Security Guide.Chapter: Access Control ListSection: How ServerIron processes ACLs


Release 12.3.01 1

Transaction Rate Limiting (TRL) and SPAM Mitigation (Policy-based Server Load Balancing) for IPv6 Pre

With release 12.3.01, the Brocade ServerIron ADX enables protection against SPAM attacks and connection attacks arriving from IPv6 prefixes in addition to IPv4 prefixes.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Policy-based SLB”Book: ServerIron ADX Security Guide.Chapter: Network SecuritySection: Transaction Rate Limit (TRL)

DNS CPU-based throttling

DNS request processing time can become very slow when CPU utilization is at a high level (90 -95%). With this feature you can direct a ServerIron ADX to reject new DNS requests when CPU utilization goes beyond a configured threshold.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Configuring DNS CPU-based throttling”


Release 12.3.001

Release 12.3.00


Disaster Recovery using Global Server Load Balancing (GSLB) in DNSSEC Environments

DNS security extensions (DNSSEC) adds security to the Domain Name System. DNSSEC validates message authenticity which is an important component of DNS security and helps mitigate cache poisoning attacks and ensures data integrity. Brocade ServerIron ADX is extending support for global server load balancing (GSLB) in DNSSEC environments; thereby providing disaster recovery for mission-critical applications. In addition, the Brocade ServerIron ADX provides efficient traffic distribution among DNSSEC servers while operating in stateful or stateless mode.

Book: ServerIron ADX Server Load Balancing GuideChapter: Stateless Server Load BalancingSection:“Fragmentation support in the stateless mode”

SOAP/XML Application Programmatic Interface (API)

The Brocade ServerIron ADX is extending support for an XML API over SOAP to foster information exchange between a ServerIron ADX and an external orchestration software or tool. This enables service provider and enterprise customers to communicate with a Brocade ServerIron ADX from their familiar programming environments such as PERL, JAVA etc, and gain additional control over their application delivery infrastructures. The following is a brief summary of control functions available through the SOAP/XML API:• Virtual server and port configuration• Real server and port configuration• Traffic statistics.• System resource checks


IS-IS support & IS-IS Route Health Injection (IPv4 and IPv6

With this release, support is extended for the IS-IS routing protocol for both IPv4 and IPv6 prefixes: • Support for level 1, level 2 and level 1+2 router types• Support for IS-IS peering and related timers • Support for Hello packet padding• Support for router priority setting for designated router

(pseudo node) election• Use of "multicast" MAC for IS-IS packet exchange

(hello, LSA) with peers• Support for Equal Cost multi-path load balancing

(ECMP)• Support for peer authentication modes: MD5 and

clear-text• IS-IS Route filtering - distribute list to deny routes• Disaster Recovery with IS-IS route health injection

Book: ServerIron ADX Switch and Router Guide.Chapter: Configuring IS-IS (IPv4)Chapter: Configuring IPv6 IS-IS

Traffic Segmentation The traffic segmentation capability in release 12.3 allows customers to implement additional security measures and meet several PCI compliance guidelines. This functionality ensures that traffic between SLB domains on the same ServerIron ADX flows through an upstream layer3 device such as a firewall instead of switching locally.

Book: ServerIron ADX Security Guide.Chapter: Network SecuritySection: Traffic Segmentation


Release 12.3.00 1

Layer 7 Persistence based on Server inserted Cookie

The Brocade ServerIron ADX is adding intelligence to inspect cookies inserted by application servers and provides flow persistence based on inserted cookie values. This greatly simplifies load balancing in certain environments where persisting based on a server-inserted cookie is critical to achieve flow integrity.

Book: ServerIron ADX Server Load Balancing GuideChapter: Layer 7 Content SwitchingSection: “Server passive cookie persistence”

Jumbo Frame support The release 12.3 extends support for larger packet sizes up to 9K bytes in IPv4 server load balancing, transparent cache switching and firewall load balancing environments.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Configuring a TCP MSS value at the TCP profile level”

Fragmentation support in the stateless mode

By default, fragmentation is not supported in the Stateless Server Load Balancing mode. Consequently, fragmented packets are dropped. This feature allows you to configure fragmentation support for a specified port in the stateless mode.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Fragmentation support in the stateless mode”

Event logging The Event Logging feature of the ServerIron ADX captures all of the activity on the MP and BP consoles and saves it in a file named "eventlog.txt" which is saved on the internal USB drive. This log captures all of the following information along with a timestamp:• Syslog messages when they are logged• All MP console messages (boot and application)• All BP console messages on each Core (boot and

application)• All CLI commands typed by users at the MP and BP

consoles• All commands typed at the OS prompt

Book: ServerIron ADX Administration GuideChapter: ServerIron System ManagementSection: Event Logging


Release 12.2.11

Release 12.2.1


VIP Route Health Injection (RHI) for IPv6

Brocade ServerIron ADX offers two approaches for achieving traffic distribution among multiple sites: global server load balancing (GSLB) and VIP route health injection. Both methods provide traffic distribution and site failure protection. Unlike GSLB, VIP route health injection is independent of the DNS infrastructure. It relies on the underlying routing infrastructure to achieve load balancing. Starting with this release, Brocade ServerIron ADX is extending support for VIP route health injection to IPv6 application services. This allows injection of IPv6 VIP routes inside the OSPF version 3 routing process meant for carrying IPv6 routes. Consequently administrators can now roll-out VIP route health injection based multi-site redundancy solutions for both IPv4 and IPv6 application services.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “VIP route health injection”

Weighted Round Robin Static - A New Load Balancing Predictor

Predictors or load balancing algorithms play an important role in achieving traffic distribution among application servers. Brocade ServerIron ADX supports a variety of predictors including: least connections, round-robin, enhanced weighted, dynamic weighted and response time. Many of these predictors are connection-based which means that the application servers are picked based on the current connection load situation. While this is ideal in most situations, some designs require different treatment for traffic distribution. To handle such designs, Brocade is offering a new weighted-round-robin-static predictor that is completely agnostic of current connection load.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Static Weighted Round Robin predictor”

Auto Enable / Disable SYN Proxy Attack Protection

Brocade ServerIron ADX offers one of the best solutions in the industry for protection against TCP SYN attacks. This functionality is disabled by default and can be enabled on a per-interface basis. This release offers additional intelligence to automatically switch attack protection on-or-off depending on thresholds that are pre- specified by the administrator. When the connection rate exceeds a specified "ON-threshold", the SYN proxy mechanism is enabled automatically, and when the connection rate drops below a specified "OFF-threshold", the SYN proxy mechanism is disabled. This helps minimize connection establishment latency associated with proxy connections when infrastructure isn't under attack.

Book: ServerIron ADX Security GuideChapter: Syn-Proxy and DoS ProtectionSection: Syn-Proxy auto controlSection: Configuring Syn-Proxy auto control

Passive FTP support for Transparent Cache Switching Designs

The Brocade ServerIron ADX provides for optimal distribution of traffic among cache servers through its Transparent Cache Switching or Redirection feature. This feature improves the cache-hit ratio and saves WAN bandwidth cost. The commonly used File Transfer Protocol (FTP) can run in either of the two modes: active FTP or Passive FTP. Previously, ServerIron ADX only offered support for transparent cache switching with Active FTP. This release extends transparent cache switching support to Passive FTP.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: Transparent Cache SwitchingSection: Passive FTP for TCS


Release 12.2.1 1

Creating a Master Password for export of SSL keys

This feature allows you to create a master password that grants permission to export all SSL keys on a ServerIron ADX using SCP copy.

Book: ServerIron ADX Security GuideChapter: Secure Socket Layer (SSL) AccelerationSection: Creating a Master Password for export of SSL keys

Cache Server Persistence based on Custom String

In a transparent cache redirection solution, it is critical to provide cache server persistence to minimize content duplication, maximize cache-hit ratio and save WAN bandwidth.Prior releases of Brocade ServerIron ADX offered cache persistence based on the following: IP address, requested URL path, requested URL host name and requested URL parameters. This release extends this list by offering persistence based on custom string within a requested hostname or URL. A common example where this feature can be helpful is with video streams that users download from the Internet. Because each of these video streams has a unique video-id, the cache hit ratio can be significantly improved by persisting on a unique video-id string that resides inside requested URL.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: Configuring TCSSection: Cache Persistence using hashing on a portion of the URL

Change to Cache Persistence using URL Hashing

In previous versions of the ServerIron ADX software, this feature was configured using the csw-hash url command within the server cache-group configuration. With this release, it is configured as an match option within a CSW policy configuration. The previous command is no longer available.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: Configuring TCSSection: Cache Persistence using hashing on a portion of the URL


Release 12.2.11

ASM4 Product Bundle Brocade is pleased to announce general availability of a new ASM4-based ADX 4000 bundle. This bundle extends the ServerIron ADX 4000 family and offers a new entry-level, modular application delivery controller platform. The bundle is delivered pre-configured with: • one ASM4 application switch module (a

software-restricted flavor of ASM8 module)• one management module• one 12-port Gigabit Ethernet fiber line card • eight Gigabit Ethernet copper SFP connectors• two AC power supplies • premium software. The ASM4 module is enabled for four application cores, and is upgradeable to eight application cores through the capacity-on-demand feature of the ServerIron ADX. Using a simplified, software license-upgrade approach, you can double application throughput capacity of the ASM4 bundle from 9 Gbps to 17.5 Gbps. If you add a second ASM8 module, then the performance will increase to 35 Gbps. This ASM4 bundle must run the Brocade ServerIron ADX software release 12.2.1 or later.

Book: ServerIron ADX Installation GuideChapter: Product OverviewSection: Application Switch Module (ASM)Book: ServerIron ADX Administration GuideChapter: Capacity on DemandSection: Software-based licensing overview

Multi-Zone Firewall Load Balancing

The Brocade ServerIron ADX offers a powerful load balancing solution for infrastructure devices such as firewalls. You can distribute traffic load among multiple low-end or high-end firewalls and achieve flow persistence using the Brocade ServerIron ADX devices, and thereby achieve maximum return on your investment.Previously, the Brocade ServerIron ADX supported firewall load balancing for up to 3 zones: internal, external and DMZ zones. With this release, support is extended for up to 8 zones for larger deployments that involve firewall devices supporting more than 3 zones. The number of firewall paths has been raised from 32 to 64, while the maximum supported firewall count is kept at 16.

Book: ServerIron ADX Firewall Load Balancing GuideChapter: Configuring Multizone FWLB Chapter: ServerIron FWLB Overview Section: FWLB configuration limits


Release 12.2.0 1

Release 12.2.0


TCP/UDP Content Switching

TCP/UDP content switching allows the ServerIron ADX to make switching decisions based on the content of TCP and UDP traffic.

Book: ServerIron ADX Server Load Balancing GuideChapter: Layer 7 Content SwitchingSection: “TCP/UDP content switching”

Dedicated Next Hop per VIP for Reverse SLB Traffic

This feature allows you to configure a default gateway for reverse SLB traffic at the Virtual server level.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Dedicated next hop per VIP for reverse SLB traffic”

Increasing TCS Hash Bucket Count

This feature allows you to increase the TCS hash bucket count to a higher number to ensure a more reasonable distribution of excess traffic among remaining cache servers when a cache server goes down.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: Configuring TCSSection: Increasing TCS hash bucket count

Enabling hardware-based multicast switching

Where there are high amounts of multicast traffic, this feature allows you to configure hardware-based multicastswitching on a ServerIron ADX to enable the ingress port to flood multicast traffic across the VLAN instead of sending it to the management module.

Book: ServerIron ADX Switch and Router GuideChapter: Configuring Basic Layer-2 parametersSection: Enabling hardware -based multicast switchingSection: Trunking configured with Hardware-based Multicast Switching

Configuring a Real Port as TCP-only or UDP-only

This feature allows you to configure a ServerIron ADX to allow traffic to a virtual port being load-balanced to a different set of real ports based on its protocol (TCP or UDP).

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Configuring a real port as TCP only or UDP only”


Release 12.2.01

Response time load balancing

This feature Distributes traffic among real servers based on a dynamic weight value that is derived from the response time of health check packets.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Server response time”Section: “Changing the Load-Balancing Predictor Method”Section: “Configuring the smooth factor”

Cache Persistence using URL Hashing

The ServerIron ADX enables traffic distribution among cache servers in a TCS setup after inspecting and hashing based on the request URL. This enables cache persistence based on the requested URL and minimizes duplication of content among multiple cache servers.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: Configuring TCSSection: Cache Persistence using URL Hashing

Default CSW Forwarding to the Internet

In previous released, when no rule in a CSW policy was matched, the traffic was dropped by default. With this release, when no CSW rule is matched, traffic is forwarded to the Internet by default.

Book: ServerIron ADX Server Load Balancing GuideChapter: Layer 7 Content SwitchingSection: “CSW policies”

Display of Layer 7 cache buckets

The show cache-group command has been enhanced to display the number of Layer 7 cache buckets.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: Configuring TCSSection: Displaying Cache Information

Port holddown timer When configured, this feature prevents a failed port from being marked active until a configurable time period has elapsed.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “Port holddown timer”

IPv6 to IPv4 Gateway This feature allows an IPv6 client to send and receive packets to and from an IPv4 server.

Book: ServerIron ADX Server Load Balancing GuideChapter: IPv6 Support for Server Load BalancingSection: “IPv6 to IPv4 gateway”

Setting a DSCP value for SIP heath check

This feature allows you to set a DSCP value in the IP header of SIP health-check packets.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: SIP Server Load BalancingSection: Configuring a DSCP value for SIP health checks


Release 12.2.0 1

QOS marking of SLB packets

This feature allow you to configure a ServerIron ADX to set the DSCP bits to a configured value in all packets sent to servers bound to a specified VIP. This feature can be used with Layer-3 DSR servers that are appropriately coded with additional intelligence to interpret DSCP marked packets and send them directly to the clients.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: “TOS marking of SLB and health check packets”

SNMP-based Cache Server Load Balancing

This feature allows you to use SNMP to monitor the load on cache servers and load-balance the cache servers using that information.

Book: ServerIron ADX Advanced Server Load Balancing GuideChapter: Configuring TCSSection: SNMP-based cache server load balancing

Enhanced Support for root and intermediate CA certificates.

This features provides Support for up to 32 DN names for all root and intermediate CA certificates.

Book: ServerIron ADX Security GuideChapter: Secure Socket Layer (SSL) AccelerationSection: Configuring a CA Certificate File

Increased certificate chain depth.

This feature allow you to increase certificate chain depth within an SSL profile from the default of 4 up to a maximum of 10

Book: ServerIron ADX Security GuideChapter: Secure Socket Layer (SSL) AccelerationSection: Configuring certificate chain depth

Enhancements to GUI With this release, two new functions are added to the Graphical User interface:• Software Upgrade• Application Template

Book: ServerIron ADX Graphical User Interface GuideChapter: Configuring Server Load BalancingChapter: Maintenance

Capacity on Demand Software and hardware features of both fixed-configuration (ServerIron ADX 1000 series) and chassis (ServerIron ADX 4000 and 10000) ServerIron ADX application switches can be obtained at time of purchase or upgraded later through software-based licensing.

Book: ServerIron ADX Administration GuideChapter: Capacity on Demand


Release 12.1.001

Release 12.1.00


SSL Acceleration(configuration)

With this release, ServerIron ADX supports integrated hardware-based SSL acceleration. The referenced section describes how the feature works and how to configure software for it.

Book: ServerIron ADX Security GuideChapter: Secure Socket Layer (SSL) Acceleration

SSL Acceleration(hardware)

This referenced section describes the hardware required for SSL acceleration and how to install it.

Book: ServerIron ADX Installation Guide

Boot and FPGA Automated Upgrade

When you reload your system with version 12.1.00 of the software, it automatically checks to see if the boot code and FPGA code on your system are compatible with the application image being loaded. If you have an older version of the boot code or FPGA code, it will be displayed and you will be directed to use the boot upgrader command to load the appropriate code.

Book: Release Notes for TrafficWorks Software Release 12.1.00 Section: Upgrading Boot and FPGA Code

Track Trunk Port with VRRP-E

The Track Trunk Port with VRRP-E feature allows the ServerIron ADX to track the failure of individual ports within a trunk. When a tracked port within a trunk fails, the VRID priority value is changed, which changes the failover value.

Book: ServerIron ADX Switch and Router GuideChapter: Configuring VRRP and VRRP-ESection: Track Trunk Port with VRRP-E

Management Port With this release, the ServerIron ADX supports an Ethernet port that is designed for managing the device. This port allows you to provide management access to a ServerIron ADX on a separate and more secure network than the one where general network traffic is being passed. This access is provided through an RJ-45 connector on the front panel of the ServerIron ADX 1000 platforms or on the management module for ServerIron ADX chassis products.

Book: ServerIron ADX Administration GuideChapter: ServerIron ADX System ManagementSection: Using the Management Port

UDLD for Tagged and Untagged ports

With this release, Uni-Directional Link Detection (UDLD) support for Tagged and Untagged ports has changed. See the referenced document for details.

Book: ServerIron ADX Switch and Router GuideChapter: Configuring Uni-Directional Link Detection (UDLD)Section: Configuring UDLD

Single link LACP This release supports single-link LACP on the ServerIron ADX. A single instance of link aggregation (single-link LACP) can be used to provide unidirectional link detection. Single-link LACP is based on the 802.3ad LACP protocol, but allows you to form an aggregated link with only one Ethernet port.

Book: ServerIron ADX Switch and Router GuideChapter: Configuring Trunk Groups and Dynamic Link AggregationSection: Single link LACP


Release 12.1.00 1

Any port static/LACP trunks

In previous versions of the ServerIron ADX, ports in a trunk had to be in continuous groups. Now you can configure any eight ports in a static or LACP trunk.

Book: ServerIron ADX Switch and Router GuideChapter: Configuring Trunk Groups and Dynamic Link AggregationSection: Trunk Group Rules

IPv6 This release supports the IPv6 protocol. Book: ServerIron ADX Switch and Router GuideChapter: Configuring IPv6 AddressingChapter: Configuring IPv6 Dynamic RoutingBook: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: IPv6 Support for SLB

sFlow This release introduces the sFlow feature to the ServerIron ADX. sFlow is a system for observing traffic flow patterns and quantities within and among a set of ServerIron ADX devices

Book: ServerIron ADX Switch and Router GuideChapter: sFlow

Syn-cookie threshold trap

This release supports the configuration of a syn-cookie threshold trap.

Book: ServerIron ADX Security GuideChapter: Network SecuritySection: Syn-cookie threshold trap

Minimum Health Servers on a VIP port

With this feature, you can configure a VIP port to carry traffic only when a configured minimum number of real server ports that are bound to the VIP port are healthy and in the UP state.

Book: ServerIron ADX Server Load Balancing GuideChapter: Server Load BalancingSection: Minimum healthy servers on a VIP port

Route Only The Route Only feature allows one port or all ports in a system to be configured in a mode where only packets meant for Layer-3 forwarding are forwarded by the system.

Book: ServerIron ADX Switch and Router GuideChapter: Configuring Base Layer-3Section: Disabling Layer 2 switching

Role Based Management

Role Based Management (RBM) allows a user to view and/or update configurations, including virtual servers, real servers, and csw policies, without being able to view or edit configurations associated with another user.

Book: ServerIron ADX Administration GuideChapter: Role Based Management

Configuring Failover based on the number of Active Virtual Ports

With this feature, you can configure the active-standby peer to fail over based on the number of router ports and active virtual ports.

Book: ServerIron ADX Server Load Balancing GuideChapter: High AvailabilitySection: Configuring failover based on the number of active virtual ports


Release 12.1.001

Delayed High Availability Failover

With this feature configured, when a ServerIron ADX switch detects a failover condition because of a VIP/VPORT count change, the failover is delayed and re-examined after a configured time period.

Book: ServerIron ADX Server Load Balancing GuideChapter: High AvailabilitySection: Delayed Failover

Syn-cookie with Packet Buffering

In this release, packet buffering has been increased from one to six packets.

N/A



Chapter

2
Server Load Balancing
OverviewThe Application Delivery Controllers (ADC) such as Brocade ServerIron ADX help ease the administration of TCP-based or UDP-based applications. They provide server load balancing (SLB) for the application servers, help offload CPU-intensive tasks from the application servers, and provide added security to the server farm.

In Figure 1, the system administrator has greater flexibility in managing application server resources. By using a ServerIron application delivery switch, the system administrator can seamlessly add or remove the application servers (real servers) and handle the changing traffic requirements without disrupting service to the end-users. The application clients access the virtual IP address or VIP (virtual server) that is hosted by the ServerIron ADX.

In addition to offering increased control over server resources, the ServerIron ADX offers numerous other functions, such as application health checks, server offload, and greater security.

FIGURE 1 Single virtual IP address mapped to multiple real servers

The server load balancing (SLB) requires associations between the application servers (real servers) and the virtual server (VIP). The associations are done by binding TCP or UDP ports on the real servers with TCP or UDP ports on the virtual server. When a client sends a TCP or UDP request to an application port defined under the virtual server, then the ServerIron identifies one of the back-end application servers based on the configured load balancing method and forwards the client request to it. The client is completely unaware of this traffic distribution, but observes increased availability, faster response time and better throughput. The ServerIron can be configured to host multiple application services such as web (http), ftp, or DNS under a single virtual server.

27

Overview2

In Figure 1, an application administrator has established a web site www.example7.com. This web site is mapped to the virtual server (VIP 10.95.55.1) that is hosted on the ServerIron ADX. All queries made to this web site arrive at the virtual server. The ServerIron then distributes these queries among the four back-end application servers. The actual addresses of these four real web servers remain unknown and unseen to the end users. They observe only one IP address, which is the VIP address for the web service.

How SLB worksA Brocade ServerIron ADX running SLB software establishes a virtual server that acts as a front end to physical servers, distributing user service requests among active real servers. SLB packet processing is based on the Network Address Translation (NAT) method. Packets received by the virtual server IP address are translated into the real physical IP address based on the configured distribution metric (for example, “round robin”) and sent to a real server. Packets returned by the real server for the end user are translated by SLB so that the source address is that of the virtual server instead of the real server.

NAT is performed for both directions of the traffic flow. Converting virtual services to real services requires IP and TCP checksum modifications.

Port translation is not performed for any virtual port that is bound to a default virtual port.

Load-balancing predictorThe load-balancing predictor is an algorithm that determines how traffic is distributed among the application servers (real servers).

It is possible to fine-tune traffic distribution among servers by selecting one of the following predictors:

Least connections predictor

Sends the request to the real server that currently has the fewest active connections with clients. For sites where a number of servers have similar performance, the least connections option smooths distribution if a server gets bogged down. For sites where the capacity of various servers varies greatly, the least connections option maintains an equal number of connections among all servers. Servers that are capable of processing and terminating connections faster then receive more connections than slower servers over time.

NOTEThe Least Connections predictor does not depend on the number of connections to individual ports on a real server but instead depends on the total number of active connections to the server.

The Least Connections predictor can be applied globally to the entire ServerIron ADX or locally per virtual server as described in “Changing the Load-Balancing Predictor Method” on page 42.


Overview 2

Round Robin predictor

Directs the service request to the next server, and treats all servers equally regardless of the number of connections. For example, in a configuration of four servers, the first request is sent to Server1, the second request is sent to Server2, the third is sent to Server3, and so on. After all servers in the list have received one request, assignment begins with Server1 again. If a server fails, SLB avoids sending connections to that server and selects the next server instead. The Round Robin predictor can be applied globally to apply for the entire ServerIron ADX or locally per-virtual server as described in “Changing the Load-Balancing Predictor Method” on page 42.

Weighted Round Robin predictor

Like the Round Robin predictor, the Weighted Round Robin predictor treats all servers equally regardless of the number of connections or response time. It does however use a configured weight value that determines the number of times within a sequence that the each server is selected in relationship to the weighted values of other servers. For example, in a simple configuration with two servers where the first server has a weight of 4 and the second server has a weight of 2, the sequence of selection would occur as described in the following:

1. The first request is sent to Server1.

2. The second request is sent to Server2.

3. The third request is sent to Server1.

4. The fourth request is sent to Server1.

5. The fifth request is sent to Server2.

6. The sixth request is sent to Server1.

Notice that over this cycle of server connections, Server1, which had a weight of 4, was accessed four times and Server2, which had a weight of 2, was accessed only twice.

This cycle will repeat as long as this predictor is in use.

The Weighted Round Robin predictor can be applied globally to the entire ServerIron ADX or locally per virtual server as described in “Changing the Load-Balancing Predictor Method” on page 42.

Static Weighted Round Robin predictor

The Static Weighted Round Robin predictor makes its server selections exactly like the Weighted Round Robin predictor, however, it does not distribute the load to available barrel processors (BPs) within the ServerIron ADX. Consequently, server selection can be concurrent to better utilize your system capacity. The following description provides a simple example:

The ServerIron ADX has the following configuration:

• Two BPs are enabled and in an operating state

• Two servers are connected: Server1 with a weight of 4, Server2 with a weight of 2

For BP1, distribution occurs as described in the following.






Overview2



For BP2, distribution occurs as described in the following.







Notice that this sequence for each pair of servers is exactly the same as described in the example for the Weighted Round Robin predictor. The only difference is that these selections are being performed concurrently on each of the BPs which allows each server to be selected more frequently. This method scales to accommodate the number of processors present in the system.

The Static Weighted Round Robin predictor can be applied globally to the entire ServerIron ADX or locally per virtual server as described in “Changing the Load-Balancing Predictor Method” on page 42.

NOTETo use the static weighted round robin predictor for Layer 7, a server group must be defined for bound real servers. When all of the server’s fail to meet the Layer-7 selection criteria, load balancing will not fall back to Layer-4 server load balancing.

Weighted and Enhanced Weighted load balancing

Assigns a performance weight to each server. Weighted and Enhanced load balancing are similar to least connections, except that servers with a higher weight value receive a larger percentage of connections at a time. You can assign a weight to each real server, and that weight determines the percentage of the current connections that are given to each server.

NOTEit is required that you configure a weight for any real server that is bound to a VIP that is expected to load balance based on a weighted or enhanced weighted predictor

For example, in a configuration with five servers of various weights, the percentage of connections is calculated as follows:

• Weight server1 = 7





• Total weight of all servers = 24

The result is that Server1 gets 7/24 of the current number of connections, Server2 gets 8/24, Server3 gets 2/24, and so on. If a new server, Server6, is added with a weight of 10, the new server gets 10/34.


Overview 2

If you set the weight so that your fastest server gets 50 percent of the connections, it will get 50 percent of the connections at a given time. Because the server is faster than others, it can complete more than 50 percent of the total connections overall, because it services the connections at a higher rate. Therefore, the weight is not a fixed ratio but adjusts to server capacity over time.

The difference between weighted and enhanced-weighted load-balancing is the method of distributing the traffic after it is assigned.

Connection assignments with weighted predictor for weighted load-balancingIn weighted load-balancing, the traffic is distributed by allocating all of the required connections sequentially to the server with the greatest weight first and then to the server with the next greatest weight, followed by the server with the next greatest weight and so on, until all servers have received their share of connections. The process then repeats.

Table 1 shows the distribution pattern for Weighted Load-Balancing in an example configuration with three real servers, A, B, and C. Real Server A has a weight of 1, Real Server B has a weight of 2, and Real Server C has a weight of 3. The numbers in bold indicate which server receives the new connection. When the weighted predictor is configured, connections are assigned as shown in Table 1.

TABLE 1 SLB with the weighted predictor

Real Server A Real Server B Real Server C

weight = 1 weight = 2 weight = 3

Connections Server loada

a. For the weighted predictor, the server load is calculated as connections divided by server weight = server load. Fractional remainders are rounded down. If there is a tie, the server with the highest weight receives the connection

Connections Server load Connections Server load

0 0 / 1 = 0 0 0 / 2 = 0 0 0 / 3 = 0

0 0 / 1 = 0 0 0 / 2 = 0 1 1 / 3 = 0

0 0 / 1 = 0 0 0 / 2 = 0 2 2 / 3 = 0

0 0 / 1 = 0 0 0 / 2 = 0 3 3 / 3 = 1

0 0 / 1 = 0 1 1 / 2 = 0 3 3 / 3 = 1

0 0 / 1 = 0 2 2 / 2 = 1 3 3 / 3 = 1

1 1 / 1 = 1 2 2 / 2 = 1 3 3 / 3 = 1

1 1 / 1 = 1 2 2 / 2 = 1 4 4 / 3 = 1

1 1 / 1 = 1 2 2 / 2 = 1 5 5 / 3 = 1

1 1 / 1 = 1 2 2 / 2 = 1 6 6 / 3 = 2

1 1 / 1 = 1 3 3 / 2 = 1 6 6 / 3 = 2

1 1 / 1 = 1 4 4 / 2 = 2 6 6 / 3 = 2

2 2 / 1 = 2 4 4 / 2 = 2 6 6 / 3 = 2

2 2 / 1 = 2 4 4 / 2 = 2 7 7 / 3 = 2

2 2 / 1 = 2 4 4 / 2 = 2 8 8 / 3 = 2


Overview2

Connection assignments with enhanced weighted predictor for enhanced weighted load-balancingIn enhanced weighted load-balancing, the traffic is distributed in the same proportions as in weighted load-balancing, but the order of distribution is different. With enhanced weighted load-balancing, the real server with the greatest weight is allocated a connection first, but then the next connection is allocated to the real server with the next greatest weight, and then to the server with the next greatest weight on-down-the-line, until all servers have received their first connection. The process repeats with each real server getting a connection in sequence until each real server has connections equal to its assigned weight.

Table 2 shows the distribution pattern for Enhanced Weighted Load-Balancing in an example configuration with three real servers, A, B, and C. Real Server A has a weight of 1, Real Server B has a weight of 2, and Real Server C has a weight of 3. The numbers in bold indicate which server receives the new connection. When the weighted predictor is configured, connections are assigned as shown in Table 2.

Weighted and Enhanced Weighted predictors can be enabled as described in: “Changing the Load-Balancing Predictor Method” on page 42.

TABLE 2 SLB with the enhanced weighted predictor

Real Server A Real Server B Real Server C

weight = 1 weight = 2 weight = 3

Connections Server loada

a. For the enhanced weighted predictor, the server load is calculated as connections x [combined weights / server weight] = server load. Fractional remainders are rounded down. If there is a tie, the server with the highest weight receives the connection.

Connections Server load Connections Server load

0 0 x 6 / 1 = 0 0 0 x 6 / 2 = 0 0 0 x 6 / 3 = 0

0 0 x 6 / 1 = 0 0 0 x 6 / 2 = 0 1 1 x 6 / 3 = 2

0 0 x 6 / 1 = 0 1 1 x 6 / 2 = 3 1 1 x 6 / 3 = 2

1 1 x 6 / 1 = 6 1 1 x 6 / 2 = 3 1 1 x 6 / 3 = 2

1 1 x 6 / 1 = 6 1 1 x 6 / 2 = 3 2 2 x 6 / 3 = 4

1 1 x 6 / 1 = 6 2 2 x 6 / 2 = 6 2 2 x 6 / 3 = 4

1 1 x 6 / 1 = 6 2 2 x 6 / 2 = 6 3 3 x 6 / 3 = 6

1 1 x 6 / 1 = 6 2 2 x 6 / 2 = 6 4 4 x 6 / 3 = 8

1 1 x 6 / 1 = 6 3 3 x 6 / 2 = 9 4 4 x 6 / 3 = 8

2 2 x 6 / 1 = 12 3 3 x 6 / 2 = 9 4 4 x 6 / 3 = 8

2 2 x 6 / 1 = 12 3 3 x 6 / 2 = 9 5 5 x 6 / 3 = 10

2 2 x 6 / 1 = 12 4 4 x 6 / 2 = 12 5 5 x 6 / 3 = 10

2 2 x 6 / 1 = 12 4 4 x 6 / 2 = 12 6 6 x 6 / 3 = 12

2 2 x 6 / 1 = 12 4 4 x 6 / 2 = 12 7 7 x 6 / 3 = 14

2 2 x 6 / 1 = 12 5 5 x 6 / 2 = 15 7 7 x 6 / 3 = 14


Overview 2

Dynamic weighted predictor

ServerIron ADX provides a dynamic weighted predictor that enables it to make load balancing decisions using real time server resource usage information, such as CPU utilization and memory consumption. The ServerIron retrieves this information (through the SNMP protocol) from MIBs available on the application servers.

To achieve this capability, a software process in ServerIron, named SNMP manager (also called SNMP client) is used. This process is different from the SNMP agent process (a.k.a. SNMP server process) on the ServerIron. A ServerIron can be configured as both SNMP agent (that allows management of ServerIron through Network Management System), and SNMP manager (that facilitates the new SNMP based predictor method). In addition, all the real servers must run the SNMP agent daemon and support MIBs that can be queried by the SNMP manager of the ServerIron.

You can fine-tune how traffic is distributed across these real servers by enabling Dynamic Weighted Predictor on the ServerIron. SNMP dynamic predictor is presently not supported for IPv6 traffic.

The Dynamic Weighted predictors can be applied globally to apply for the entire ServerIron ADX or locally per virtual server as described in “Changing the Load-Balancing Predictor Method” on page 42 and “Configuring dynamic weighted predictor” on page 44.

NOTEIn ServerIron ADX, the global snmp-server command is enabled by default and this command must not be removed if the dynamic weighted predictor is configured. If this command is removed, then the ServerIron ADX will stop listening on the UDP port 161 and drop SNMP responses from the real servers that are used for this predictor.

Dynamic-weighted DirectThe SNMP response from each server is regarded as a performance weight. The displayed SNMP Weight under “show server real” is the direct weight from the SNMP response. Weighted load balancing is similar to least connections, except that servers with a higher weight value receive a larger percentage of connections at a time. The dynamic weight is polled for the specified real server, and that weight determines the percentage of the current connections that are given to the server. The default weight is 0 if it does not receive any SNMP response.

For example, in a configuration with five servers of various weights, the percentage of connections is calculated as follows:






• Total weight of all servers = 24

The result is that Server1 gets 7/24 of the current number of connections, Server2 gets 8/24, Server3 gets 2/24, and so on. If a new server, Server6, is added with a weight of 10, the new server gets 10/34.


Overview2

If the SNMP-weight indicates that your fastest server gets 50 percent of the connections, the server will get 50 percent of the connections at a given time. However, because the server is faster than others, it can complete more than 50 percent of the total connections overall by servicing the connections at a higher rate. As a result, the weight is not a fixed ratio but instead adjusts to server capacity over time.

Dynamic-weighted ReverseThe SNMP response from each server is regarded as a performance weight. Reverse-Weighted load balancing is similar to Direct-Weighted, except that the SNMP-weight will be calculated by the difference of the maximum based value and the dynamic SNMP response value (max. based value – SNMP response). The server load balance will balance the same way as the direct-weighted predictor with the dynamically calculated SNMP-weight value.

For an example of CPU usage, if you configure the maximum based value to 100% and the SNMP response is 90% of CPU usage, the SNMP weight becomes 10% (100 - 90 = 10). The server load balance does direct-weight load balancing with the 10% unused CPU time. In other words, servers with a higher SNMP response (a higher CPU usage and lower SNMP-weight) receive a lower percentage of connections at a time.

Server response time

Distributes traffic among real servers based on a dynamic weight value that is derived from the response time of health check packets. If Layer 7 health check is enabled, application response time is used. If Layer 4 health check in enabled, response time based on TCP SYN and TCP SYN ACK packets is used. The response time weight is derived from the actual time response measurement where the shorter the response time, the larger the response time weight value computed. The response time wait is calculated according to the following rules:

• If the response time is 0, the weight is 1000

• If the response time is greater than 100 ms, the weight is 1

• If the response time is between 0.1 and 100 ms, the weight is 100 divided by the response time (in 0.1 ms intervals)

The response time predictor is only applicable to TCP traffic.

The server response time predictors can be applied globally to apply for the entire ServerIron ADX or locally per virtual server as described in “Changing the Load-Balancing Predictor Method” on page 42.

Sticky connectionsWhen a service request by a client mandates a series of sequential TCP or UDP port connections to be served by the same real server, you can enable a sticky connection on that TCP or UDP virtual server port. For example, if a user is accessing dynamically generated pages, the client must consistently attach to the same server; otherwise, the state information is lost. By default, the sticky parameter is disabled for virtual service ports, except for Secure Socket Layer (SSL).


Overview 2

Application port groupsApplication groups enhance the sticky connections method by allowing you to group up to four TCP or UDP ports with another, “primary” TCP or UDP port. When the ServerIron ADX sends a client request for the primary port to a real server, requests from the same client for a port that is grouped with the primary port also go to the same real server. The application group method, like the sticky method, is governed by the sticky age.

The ServerIron ADX automatically sends requests for the grouped ports to the same real server as the “primary” port, as long as the sticky timer has not expired. You must define all the ports in an application group individually in the VIP, and you must configure all of them to be sticky.

Refer to “Multiple port binding using port aliases” on page 530 for an example of this feature.

Concurrent connectionsThe concurrent connection option is similar to the sticky option. However, instead of supporting sequential connections to the same server, the concurrent connection option supports both a primary connection and secondary connections. The connections are supported at the same time.

The primary connection is the controlling connection and dictates the resource, such as a server, to which subsequent or secondary connections are made.

When the controlling connection is established, the server dynamically assigns a TCP or UDP port to which the client should open subsequent or secondary connections. Subsequent connections from that client are accepted on the server as long as the controlling connection is still active.

Figure 2 shows an example of a concurrent connection.

FIGURE 2 Concurrent connections in operation on an SLB network

A client initiates a session request to the NETPERF application supported on servers S1, S2, and S3. When the SLB switch receives the request, the switch forwards the request to server S2. This forms the primary connection. Then S2 dynamically assigns a port, 10000, to the application and forwards it to the client.

NOTEThe method the server uses to communicate the dynamic port to the client is application-specific.

The ServerIron ADX switches all subsequent connections to S2 to ensure that the NETPERF session completes successfully.


Overview2

By default, the concurrent property of a virtual TCP or UDP service port is enabled except for FTP, Telnet, TFTP, HTTP, and SSL ports.

Remote ServersThe application servers that are a Layer 3 hop away (in other words, in a different subnet that is separated by router) are identified as remote servers in ServerIron.

Direct Server ReturnDSR (Direct Server Return) configures the ServerIron ADX to instruct real servers to send client responses directly to the clients instead of sending the responses back through the ServerIron ADX. As a result, the clients experience faster response times and the ServerIron ADX is free to support more sessions to serve more clients.

ServerIron ADX supports both Layer 2 Direct Server Return (L2 DSR) and Layer 3 Direct Server Return (L3 DSR).

• In an L2 DSR configuration, the ServerIron ADX and the real servers are on the same subnet.

• In an L3 DSR configuration, the ServerIron ADX and the real servers need not be on the same subnet; they can be connected through a router.

Understanding L2 DSR

As in standard SLB configurations, an L2 DSR-configured ServerIron ADX sends client requests addressed to a VIP to a load balanced real server. However, the ServerIron ADX does not translate the destination IP address in the client’s request from the VIP into the real server’s IP address as in other SLB configurations. Instead, the ServerIron ADX leaves the destination IP address unchanged. And the ServerIron ADX also formats the client request packets in such a way that the real servers respond directly to the clients, instead of sending the responses back through the ServerIron ADX.

For L2 DSR to work you must configure a loopback interface on each real server and give the loopback interface the same IP address as the VIP. Because the ServerIron ADX sends the client traffic to the real server without translating the destination address from the VIP into the real server's IP address, the real server receives the client traffic addressed to its loopback address and responds directly to the client.


Overview 2

Figure 3 shows an example of a ServerIron ADX deployed in an L2 DSR configuration.

FIGURE 3 ServerIron ADX in an L2 DSR configuration

The example above shows the flow of packets in which the ServerIron ADX and the real servers are Layer 2 connected.

1. The client sends a packet to an VIP on the ServerIron ADX.

2. The ServerIron ADX forwards the packets to the loopback address on the real server.

3. The real server then sends the packet directly to the client.

L2 DSR can be configured on an individual TCP or UDP port basis when you configure your virtual servers. For a complete discussion of L2 DSR and a configuration example, refer to “Configuring L2 Direct Server Return” on page 85.

Understanding L3 DSR

As with L2 DSR, a ServerIron ADX configured for L3 DSR enables application servers to respond directly to the clients resulting in faster server-to-client response times and increased connection capacity for the ServerIron ADX.

But unlike L2 DSR, which requires that the ServerIron ADX servers and clients be directly (Layer 2) connected, in an L3 DSR configuration the servers and clients can be connected using a router.

For L3 DSR to work, the ServerIron ADX must be able to inspect the DSCP field of incoming packets and modify it to a configured value. Also, the real server must be configured to use the VIP address as the source IP address in the response if the received packet has a matching DSCP field value.

A typical configuration includes servers that are one hop away where the ServerIron ADX has additional intelligence to handle health checks response packets. Figure 4 shows an example of a ServerIron ADX deployed in an L3 DSR configuration.

FIGURE 4 ServerIron ADX in an L3 DSR configuration

In the example, the ServerIron ADX inspects and modifies packets sent to a VIP. The real server uses the L3 DSR VIP as the source address in response packets if the DSCP bit value of the received packet matches the configured value.


Configuring basic SLB2

1. The client sends a packet to an L3 DSR VIP on the ServerIron ADX.

2. The ServerIron ADX modifies the DSCP field in the packet to a configured value and sends the packet to a real server.

3. The real server examines the DSCP field and (if the field matches the configured value) uses the DSR VIP as a source IP address instead of its own interface IP address. The real server then sends the packet directly to the client.

For a complete discussion of L3 DSR and a configuration example, refer to “Configuring L3 Direct Server Return” on page 90.

Configuring basic SLBTo configure basic SLB, perform the following tasks:

• Define the application servers as real servers on the ServerIron ADX. Refer to “Defining the real servers and real application ports” on page 39.

• Define a virtual server. Refer to “Defining a virtual server (VIP)” on page 40.

• Bind the real servers to the VIP. Refer to “Binding virtual and real servers” on page 41.

Figure 5 shows an example of a basic SLB configuration. This example uses multiple Web servers to handle remote Web requests received on the Web site. The Web site URL is assigned to the switch as the focal point for all inquiries as a virtual server address. The virtual server will then forward requests to each of the four Web servers as specified by the predictor (load balancing metric).

The sections following the example show how to configure the ServerIron ADX in the example using the CLI.

FIGURE 5 Basic SLB configuration


Configuring basic SLB 2

Configuration guidelinesThe following configuration guidelines should be observed when configuring SLB on a switch:

• Each virtual server name and IP address must be unique.

• Each virtual server can have multiple TCP or UDP ports assigned.

• Each real server name and IP address must be unique.

• Each real server can have multiple TCP or UDP ports assigned.

• Each real server TCP or UDP port can be bound to one or more virtual TCP or UDP ports.

NOTEIf you need to map a real server port to multiple VIP ports, you can use the multiple port binding feature. Refer to “Multiple port binding” on page 98.

• One virtual TCP or UDP port can be bound to one or more real TCP or UDP ports.

NOTEIf you need to map a real server port to multiple VIP ports, you can use the many-to-one TCP or UDP port binding feature. Refer to “Multiple port binding” on page 98.

• The default load-balancing predictor is Round Robin.

• Binding must be done to establish a relationship between virtual and real servers.

Defining the real servers and real application portsIdentify your application servers as real servers. Define a real server using its name and IP address. Add your application ports under these real servers.

ServerIronADX(config)#server real Web1 10.95.55.21ServerIronADX(config-rs-Web1)#port httpServerIronADX(config-rs-Web1)#port dnsServerIronADX(config-rs-Web1)#exit



TABLE 3 Real and virtual server assignments

Domain name Virtual IP Port Real IP Port

www.alterego.com 10.95.55.1 80 10.95.55.21 (Web1)

10.95.55.22 (Web2)

10.95.55.23 (Web3)

10.95.55.24 (Web4)

80

80

80

80


Configuring basic SLB2


Syntax: [no] server real [name] ip-address

Syntax: [no] port tcp/udp-port

The server name can be any alphanumeric string of up to 42 characters.

After you have defined the real server, you can refer to it using its name or IP address, and modify its configuration.

ServerIronADX(config)#server real Web1ServerIronADX(config-rs-Web1)#port ftpServerIronADX(config-rs-Web1)#exit

ServerIronADX(config)#server real 10.95.55.21ServerIronADX(config-rs-Web1)#port ftpServerIronADX(config-rs-Web1)#exit

ServerIronADX(config)#no server real Web1

NOTEIf a real server is not reachable from the ServerIron ADX at Layer 2 (does not respond to ARP requests from the ServerIron), then define it as a remote server.

NOTEOptionally, if you have a one-armed topology, you may need to enable source NAT along with source-ip to ensure that return traffic flows through the ServerIron ADX.

Defining a virtual server (VIP)After you define the actual Web server’s physical addresses (real server), you then need to configure the external Web server address on the switch. The external Web server is the virtual server.

It is the IP address or server name to which client browsers send requests. Add the TCP or UDP application ports the ServerIron ADX will load balance. These should be the same application ports you specified for the real servers.

To define the virtual name and address that is the access point for the company's Web site and the supported service, enter commands such as the following.

ServerIronADX(config-rs-Web4)#server virtual-name-or-ip www.example7.com 10.95.55.1ServerIronADX(config-vs-www.example7.com)#port http

Syntax: [no] server virtual-name-or-ip name ip-address


After you have defined the virtual server, you can add configuration statements or delete the server by referring to the server’s IP address or name, by entering commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip www.example7.com 10.95.55.1ServerIronADX(config-vs-www.example7.com)#port httpServerIronADX(config-vs-www.example7.com)#exit


Configuring basic SLB 2

ServerIronADX(config)#server virtual-name-or-ip 10.95.55.1ServerIronADX(config-vs-www.example7.com)#exitServerIronADX(config)#server virtual-name-or-ip www.altergo.com ServerIronADX(config-vs-www.example7.com)#exitServerIronADX(config)#no server virtual-name-or-ip 10.95.55.1

Defining a virtual server nameUse the name command to change the existing name of a virtual server.

ServerIronADX(config)#configure terminalServerIronADX(config)#server virtual-name-or-ip www.example7.com 10.95.55.1ServerIronADX(config-vs-www.example7.com)#name example8ServerIronADX(config-vs-example8)#

Syntax: name string

The string variable is the new name of the virtual server. Enter an alphanumeric name with a maximum of 42 characters without spaces or 42 characters including spaces within quotes. You can include special characters in the name.

Binding virtual and real serversAfter you define the real servers, virtual servers, and TCP or UDP ports, you need to bind the real and virtual servers together. The bindings are based on the TCP and UDP application ports you are load balancing.

To bind the four Web servers shown in Figure 5 to the virtual server address, enter the following commands.

ServerIronADX(config-rs-Web4)#server virtual-name-or-ip www.altergo.comServerIronADX(config-vs-www.example7.com)#bind http Web1 httpServerIronADX(config-vs-www.example7.com)#bind http Web2 httpServerIronADX(config-vs-www.example7.com)#bind http Web3 httpServerIronADX(config-vs-www.example7.com)#bind http Web4 http

Syntax: [no] bind tcp/udp-port-number real-server-name tcp/udp-port-number

NOTEFor clarity, the bindings in the example are shown as four separate entries. You can enter all the binding information as one command: bind http Web1 http Web2 http Web3 http Web4 http.


Changing the Load-Balancing Predictor Method2

Changing the Load-Balancing Predictor MethodThe Load-Balancing Predictor Method can be configured either globally or per-virtual server as described in the following.

To globally change the load-balancing method used by the ServerIron ADX, enter the following command.

ServerIronADX(config)#server predictor round-robin

To change the load-balancing method used by the ServerIron ADX for virtual server “v1”, enter the following commands.

ServerIronADX(config)#server virtual-name-or-ip v1ServerIronADX(config-vs-v1)#predictor enhanced-weighted

Syntax: [no] server predictor least-conn | round-robin | weighted-round-robin | weighted-round-robin-static |weighted | enhanced-weighted | dynamic-weighted direct | reverse | response-time

Selecting the least-conn parameter configures the Least Connections load-balancing method. This method is described in “Least connections predictor” on page 28.

Selecting the round-robin parameter configures the Round Robin load-balancing method. This method is described in “Round Robin predictor” on page 29.

Selecting the weighted-round-robin parameter configures the Weighted Round Robin load-balancing method. This method is described in “Weighted Round Robin predictor” on page 29.

Selecting the weighted-round-robin-static parameter configures the Static Weighted Round Robin load-balancing method. This method is described in “Static Weighted Round Robin predictor” on page 29.

Selecting the weighted parameter configures the Weighted load-balancing method. This method is described in “Weighted and Enhanced Weighted load balancing” on page 30.

Selecting the enhanced-weighted parameter configures the Weighted load-balancing method. This method is described in “Weighted and Enhanced Weighted load balancing” on page 30.

Selecting the response-time parameter configures the response time load-balancing method. This method is described in “Server response time” on page 34. Configuring the response time load balancing method requires that you configure a smooth factor as described in “Configuring the smooth factor” on page 46.

Selecting the dynamic-weighted parameter configures the Dynamic Weighted load-balancing method. This method can be configured as either direct or reverse as described in “Dynamic weighted predictor” on page 33. Details about configuring the Dynamic Weighted load-balancing method as direct or reverse are described in “Configuring dynamic weighted predictor” on page 44.

If you enable any of the weighted methods, you must configure the weights for all real servers involved. The weights can range from 0 through 65000. This configuration is described in “Configuring a weighted predictor” on page 43.

NOTEIf a given VIP port is bound to multiple ports on the same real server, then the least-connection predictor may not produce even traffic distribution. Use the round-robin predictor instead.

For overview information, refer to “Load-balancing predictor” on page 28.


Changing the Load-Balancing Predictor Method 2

Configuring a weighted predictorSeveral of the Load-Balancing Predictor Methods used on the ServerIron ADX require that weights be assigned to the real servers. The ServerIron ADX uses a formula based on each real server’s assigned weight to calculate the server load for the real servers, then selects the real server as determined by the predictor that is configured on the ServerIron ADX.

To configure a Load-Balancing Predictor Method, perform the following tasks.

1. Assign weights to the real servers.

2. Configure the weighted predictor either globally or for a virtual server.

NOTEif a real server port is bound under a VIP but a weight is not configured under the real server, the ServerIron ADX will assume the weight for that real server is 1.

Assigning weights to the real serversWhen configuring Weights on a real server, consider the following:

• Real Server Weight assignments apply to all ports configured under the real server.

• For the Weighted Round Robin predictor, server weights are assigned at the server level and not at the server port level. The load balancing, however, is based on per-server port.

• The Weighted Round Robin predictor has VIP port-level granularity. This granularity is reflected in the output from the show server session and show server conn commands, because they display output for the Weighted Round Robin predictor at a per vip-port level.

To configure weights for three real servers, enter commands such as the following.

ServerIronADX(config)#server real rsAServerIronADX(config-rs-rsA)#weight 1ServerIronADX(config-rs-rsA)#exitServerIronADX(config)#server real rsBServerIronADX(config-rs-rsB)#weight 2ServerIronADX(config-rs-rsB)#exitServerIronADX(config)#server real rsCServerIronADX(config-rs-rsC)#weight 3ServerIronADX(config-rs-rsC)#exit

Syntax: [no] weight weight-value

The weight command assigns a performance weight to each server or firewall. Servers or firewalls with a larger or higher weight assigned receive a larger percentage of connections.

The weight-value parameter specifies the real server’s weight relative to other real servers in terms of the number of connections on the server. More precisely, this weight is based on the number of session table entries the ServerIron ADX has for TCP or UDP sessions with the real server. You can specify a value from 0 through 65000. The default is 1.



Configuring the weight for real servers

This parameter specifies the weight assigned to the real server. It is used for the weighted and least connection with server response-time-weights for load balancing methods. Suppose you want to assign a higher weight to real server Web1 to bias traffic toward that server. No other changes are made to the weights of Web servers 2, 3, and 4, and they remain configured with the default weight of zero (Figure 5). Enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip www.example7.comServerIronADX(config-vs-www.example7.com)#predictor weightedServerIronADX(config-vs-www.example7.com)#server real Web1 10.95.55.21ServerIronADX(config-vs-www.example7.com)#exitServerIronADX(config)#server real Web1ServerIronADX(config-rs-Web1)#weight 10

Syntax: weight least-connections-weight

The least-connections-weight variable specifies the real server’s weight relative to other real servers in terms of the number of connections on the server. More precisely, this weight is based on the number of session table entries the ServerIron ADX has for TCP or UDP sessions with the real server. You can specify a value from 0–65000. The default is 1. This parameter is required. However, if you want to use a weight value only for the Server Response Time but not for the number of connections, specify 0 for this parameter.

If you enter a value for response-time-weight, the ServerIron ADX adds the two weight values together when selecting a real server. If you specify equal values for each parameter, the ServerIron ADX treats the weights equally. The number of connections on the server is just as relevant as the server’s response time. However, if you set one parameter to a higher value than the other, the ServerIron ADX places more emphasis (weight) on the parameter with the higher value. For example, if you specify a higher server response time weight than the weight for the number of connections, the ServerIron ADX pays more attention to the server’s response time than to the number of connections it currently has when considering the real server for a new connection.

Configuring dynamic weighted predictorThis section contains the following sections:

• “Configuring a real server with SNMP query requirements” on page 44

• “Configuring a virtual server with a dynamic weighted predictor” on page 45

Configuring a real server with SNMP query requirementsA list of the SNMP Object ID (OID) can be configured under a real server. An OID represents the weight of the real server, for example server CPU utilization or its memory usage.

To configure SNMP query requirements use the following command.

ServerIronADX(config-rs-rs1)#snmp-request oid 1 1.3.6.1.2.1.25.3.3.1.2.1

Syntax: snmp-request oid ID string

The ID parameter specifies the snmp-request entry identification, decimal value 1 through 256.

The string parameter specifies the ASCII string ASN.1 format. In this example, 1.3.6.1.2.1.25.3.3.1.2.1.


Changing the Load-Balancing Predictor Method 2

SNMP versions 1 and 2 use community strings to restrict SNMP access. The administrator must configure an SNMP community string to match with those configured in all the real servers.

ServerIronADX(config-rs-rs1)#snmp-request community public

Syntax: snmp-request community public port

The port parameter specifies the snmp-request host UDP port (Default: port 161).

You can configure the frequency of the periodic SNMP queries using the following command.

ServerIronADX(config)#server snmp-poll 5

Syntax: server snmp-poll num

The num parameter specifies the decimal value in seconds (Default: 3 sec.).

Configuring a virtual server with a dynamic weighted predictor

Select a dynamic-weighted direct or reverse predictor and an SNMP OID.

Dynamic-weighted direct

To configure a dynamic-weighted reverse predictor, use the following command.

ServerIronADX(config-vs-vs1)#predictor dynamic-weighted direct oid 1

Syntax: predictor dynamic-weighted direct oid ID

Configuration example server virtual-name-or-ip vs1 10.1.1.151 predictor dynamic-weighted direct oid 1 port http bind http rs1 http rs2 http rs3 http

Dynamic-weighted reverse

To configure a dynamic-weighted reverse predictor, use the following command.

ServerIronADX(config-vs-vs1)#predictor dynamic-weighted reverse oid 1 max 50

Syntax: predictor dynamic-weighted reverse oid ID [max value]

DECIMAL Max value - reverse weight = direct weight

Configuration exampleServerIronADX(config)#server snmp-poll 5ServerIronADX(config)#server real rs1 10.1.1.1 snmp-request community public port 161 snmp-request oid 1 1.3.6.1.2.1.25.3.3.1.2.1 snmp-request oid 2 1.3.6.1.2.1.1.3.0 port http port http keepaliveServerIronADX(config)#server virtual vs1 10.200.1.1 predictor dynamic-weighted direct oid 1



Configuring the smooth factorThis section applies to the server response time load balancing method.

The ServerIron ADX calculates the server response time value for a real server by regularly collecting response time samples, then using a calculation to smooth the values of the samples and derive a single response time value for the real server. The ServerIron ADX relies on the health-check traffic to sample the response time. As the default interval of health checks to real servers is five seconds, the ServerIron ADX collects the response time samples for every five seconds. The sampling rate can vary slightly depending on the processing the ServerIron ADX is performing.

To smooth the samples out, the ServerIron ADX uses the following calculation:

R = ((S * previous_R) + ((100 - S) * new_R)) / 100

where:

R = Response time

S = smooth factor, which is configurable and can be from 1–99. The default is 60. A large value gives the previous response time more weight than the new response time. A small value gives the new response time more weight than the previous response time.

For example, if a given real server’s previous response time value was two milliseconds, and a new measurement also results in two milliseconds, the calculated server response time using the default smooth factor is as follows:

R = ((90 * 2) + ((100 - 90) * 2) / 100

R = 180 + 20 / 100

R = 200 / 100

R = 2

If the real server’s response time slows due to processing for additional connections, the slower response time affects the Server Response Time calculation for the server. For example, if the next server response time sample is five milliseconds instead of two, the Server Response Time calculation is as follows:

R = ((90 * 2) + ((100 - 90) * 5) / 100

R = 180 + 50 / 100

R = 230 / 100

R = 2.3

Since the real server’s response time has slowed by two and a half times, the server’s response time calculation biases the ServerIron away from selecting that server for new connections.

You can affect the degree of difference in subsequent response time weights by changing the smooth factor (S). For example, if you change the smooth factor from 90 (the default) to 50, the calculations shown above have the following results:


Real server ports 2

Here is the calculation when the previous and new response times are 2 milliseconds:

R = ((50 * 2) + ((100 - 50) * 2) / 100

R = 100 + 100 / 100

R = 200 / 100

R = 2

Here is the calculation if the server’s next response time is 5 milliseconds.

R = ((50 * 2) + ((100 - 50) * 5) / 100

R = 100 + 250 / 100

R = 350 / 100

R = 3.5

Notice that the differences between the first and second samples are much greater when the smooth factor is 50 than when the smooth factor is 90. A large value gives the previous response time more weight than the new response time. A small value gives the new response time more weight than the previous response time.

You can change the smooth factor on an individual virtual server’s application port basis.

If you change the smooth factor for a virtual server, the change affects all Server Response Time calculations for the real servers bound to the virtual server.

If you change the smooth factor for an application port, the change affects Server Response Time calculations only for port bindings that use that application port.

To change the smooth factor for a virtual server’s application port, enter a command such as the following at the configuration level for the virtual server:

ServerIronADX(config-vs-Joes_Garage)#port 80 smooth-factor 50

Syntax: [no] smooth-factor num

The num variable specifies the smooth factor value the server response time calculation uses. You can specify a number from 1–99. The default is 60.

Real server portsYou can globally configure an application port by configuring its port profile. When you configure a port profile, the parameters in the profile apply to all servers that include the application port. To configure a port profile, refer to “Port profiles and attributes” on page 243.

You also can locally define some SLB port parameters on an individual real-server basis:

• State (enabled or disabled) – Ports are enabled by default.

• Keepalive health check state – Keepalive health checks are enabled if you have configured a port profile for the port and did not globally disable the health check. You can disable the keepalive health check locally for the port on a specific real server while leaving the health check globally enabled.


Real server ports2

• Layer 7 health check parameters – For some application ports that are known to the ServerIron ADX, you can customize the Layer 7 health checks for individual real servers.

NOTEFor the HTTP ports, you also can configure Layer 7 health checks for Transparent Cache Switching.

Disabling or re-enabling application portsApplication ports are enabled by default. To disable an application port on a real server, use either of the following methods.

To disable an application port, enter commands such as the following.

ServerIronADX(config)#server real Sy_Borg 192.168.4.69ServerIronADX(config-rs-Sy_Borg)#port http disable

Syntax: [no] port tcp/udp-port disable | enable

To re-enable a port, enter commands such as the following.

ServerIronADX(config)#server real Sy_Borg 192.168.4.69ServerIronADX(config-rs-Sy_Borg)#no port http disable

To disable all the application ports on a real server, enter the following command at the configuration level for the server.

ServerIronADX(config-rs-R1)#port disable-all

To re-enable all the application ports, enter the following command.

ServerIronADX(config-rs-R1)#no port disable-all

Syntax: [no] port disable-all

Globally disabling application portsYou can globally disable a Layer 4 port on the ServerIron ADX. The port can be disabled for all real servers, all virtual servers, or all real and virtual servers. After you disable a port globally, you can enable the port on individual real or virtual servers as necessary. By default, all real and virtual ports are enabled.

When the ServerIron ADX is booted, if the command to globally disable a real or virtual port exists in the startup-config file, the specified port is disabled at startup. When a real or virtual port is created, and the port has been disabled globally, the real or virtual port is disabled as well. You must enable the port explicitly.

To disable all real HTTP ports, enter the following commands.

ServerIronADX(config)#server port 80ServerIronADX(config-port-http)#disable realServerIronADX(config-port-http)#

To disable all virtual HTTP ports, enter the following commands.

ServerIronADX(config)#server port 80ServerIronADX(config-port-http)#disable virtualServerIronADX(config-port-http)#


Real server ports 2

To disable all real and virtual HTTP ports, enter the following commands.

ServerIronADX(config)#server port 80ServerIronADX(config-port-http)#disableServerIronADX(config-port-http)#

Syntax: disable [real | virtual]

Disabling SLB to a server when an application goes downBy default, if an application on a real server becomes unavailable, but the real server itself is still up, the ServerIron ADX continues to include the real server in its load balancing decisions for the application. For example, if the HTTP application on a real server stops responding to Layer 4 health checks, but the real server continues to respond to Layer 3 health checks (IP pings) from the ServerIron ADX, the ServerIron ADX continues to forward HTTP requests to the real server.

NOTENew connections are only sent to servers that have passed an application health check.

In some configurations, such as those that use a cluster of servers for an application, you may want to configure the ServerIron ADX to stop sending requests to a server when the requested application is down on the server. For example, this feature is useful in an NFS configuration.

When you enable this feature, the ServerIron ADX resets the connection for an unavailable TCP or UDP application on a real server in addition to redirecting future requests away from this real server.

To enable the feature, enter commands such as the following:

The previous example enables the feature for the http application defined under the virtual server. Similarly, this feature can be enabled for the other application ports as well.

Syntax: [no] port application-port reset-on-port-fail

Slow-start mechanismWhen the ServerIron ADX begins sending client requests to a real server that has recently gone online, it allows the server to ramp up by using the slow-start mechanism. The slow-start mechanism allows a server (or a port on the server) to handle a limited number of connections at first and then gradually handle an increasing number of connections until the maximum is reached.

The ServerIron ADX uses two kinds of slow-start mechanisms:

• The non-configurable server slow-start mechanism applies to a real server that has just gone online.

• The configurable port slow-start mechanism applies to individual TCP application ports that have just been activated on a real server.

Refer to “Slow-start mechanism” on page 284 for more information.

ServerIronADX(config)#server virtual vip-test 10.50.1.250ServerIronADX(config-vs-vip-test)#port httpServerIronADX(config-vs-vip-test)#port http reset-on-port-failServerIronADX(config-vs-vip-test)#


Real server ports2

Enabling or disabling the keepalive health checkWhen you configure a port profile for an application port, the L4/L7 keepalive health check for that port is enabled automatically. You also can enable or disable the keepalive health check for an application port on a specific real server, without affecting the global setting for the health check.

NOTEIf you configured a port profile for the port, the keepalive health check is enabled.

To enable the keepalive health check, enter commands such as the following.

ServerIronADX(config)#server real Auto_Plooker 192.168.2.69ServerIronADX(config-rs-Auto_Plooker)#port http keepalive

To disable the keepalive health check, enter commands such as the following.

ServerIronADX(config)#server real Auto_Plooker 192.168.2.69ServerIronADX(config-rs-Auto_Plooker)#no port http keepalive

Syntax: [no] port tcp/udp-port keepalive

Configuring a real port as TCP only or UDP onlyThis feature allows you to configure a ServerIron ADX to allow traffic to a virtual port being load-balanced to a different set of real ports based on its protocol (TCP or UDP). No configuration change is required for the virtual server. A virtual port can be bound to TCP only and UDP only and a regular real port at the same time.

By default, a real port accepts both TCP and UDP traffic. If a real port is configured as TCP only, when a given traffic is UDP traffic, the real port will not participate in the server selection, even if it is bound to the virtual port. Similarly, a UDP-only port will not be considered for TCP traffic.

The behaviors of all predictors remain unchanged among eligible real ports (i.e., TCP only and regular real ports for TCP traffic, and UDP only and regular real ports for UDP traffic).

The port portnum tcp-only and udp-only commands for a real port are configured under the real configuration mode as shown in the following.

ServerIronADX(config)#server real R1 10.10.10.1ServerIronADX(config-rs-R1)#port 80 tcp-onlyServerIronADX(config-rs-R1)#exitServerIronADX(config)#server real R2 10.10.11.1ServerIronADX(config-rs-R2)#port 80 udp-only

Syntax: [no] port portnum {tcp-only | udp-only}

The portnum variable specifies the application port you want to make TCP only and UDP only.

TCP only and UDP only are mutually exclusive. When the tcp-only keyword is configured, the udp-only keyword cannot be configured for a port at the same time. The udp-only keyword will be automatically disabled if the tcp-only keyword is configured, and vice versa.


Real server ports 2

Configuring a stateless portBy default, the ServerIron ADX creates session table entries for sessions between clients and applications on real servers. The ServerIron ADX uses the session table entries to maintain state information for the sessions. The ServerIron ADX uses the state information for features such as health checking and session failover in hot-standby HA configurations.

You can configure individual application ports to be stateless. The ServerIron ADX does not maintain state information for a stateless port. Making a port stateless is useful when you want to conserve session table resources or when you have configured the VIP to be transparent.

For examples and configuration information, refer to Chapter 3, “Stateless Server Load Balancing”.

To configure an application port to be stateless, enable the stateless parameter on the port in the virtual server, such as the following.

ServerIronADX(config)#server real R1 10.10.10.1ServerIronADX(config-rs-R1)#port httpServerIronADX(config-rs-R1)#exitServerIronADX(config)#server real R2 10.10.11.1ServerIronADX(config-rs-R2)#port httpServerIronADX(config-rs-R2)#exitServerIronADX(config)#server virtual-name-or-ip StatelessHTTP 192.168.4.69ServerIronADX(config-vs-StatelessHTTP)#port http statelessServerIronADX(config-vs-StatelessHTTP)#bind http R1 httpServerIronADX(config-vs-StatelessHTTP)#bind http R2 http

Syntax: [no] port tcp/udp-portnum stateless

The tcp/udp-portnum variable specifies the application port you want to make stateless.

NOTEThe ServerIron ADX supports port translation for stateless SLB. Port translation is useful when clients connect to real servers directly. Without port translation, if a client connects to a real server directly, the ServerIron ADX automatically replaces the source IP address to a VIP. When you configure port translation, the ServerIron ADX overcomes the limitation of performing NAT on all packets initiated from the real server. NAT does not occur because the ServerIron ADX does not match the port number.

NOTEThe ServerIron ADX supports stateless SLB for any TCP and UDP application protocols. For a TCP application, hashing must be enabled on the ServerIron ADX. For a UDP application, you can enable or disable hashing on the ServerIron ADX.


Adding a source IP address2

Adding a source IP addressYou can define source IP addresses on a ServerIron ADX system running switch code to place it in a multi-netted environment. These source IP addresses can potentially be used as default gateways for real servers. You can also define source NAT IP addresses while using source NAT.

The additional IP addresses allow you to deploy the ServerIron ADX in multi-netted environments, including the following examples:

• The ServerIron ADX and real servers are on different subnets.

• The remote access server (RAS) and ServerIron ADX are on different subnets.

• The border access router (BAR) and ServerIron ADX are on different subnets.

Refer to “Web hosting with ServerIron ADX and real servers in different subnets” on page 534 for an example of the type of configuration in which you need to use this feature.

NOTEDepending on the configuration, you might also need to enable source NAT. Refer to “Web hosting with ServerIron ADX and real servers in different subnets” on page 534 for general information about the NAT operations performed by the ServerIron ADX.

The ServerIron ADX supports a maximum of 64,000 simultaneous connections on each source IP address. This maximum value is based on the architectural limits of IP itself. As a result, if you add only one source IP address, the ServerIron ADX can support up to 64,000 simultaneous connections to the real servers. If you configure 64 source IP addresses, the ServerIron ADX can support more simultaneous connections.

ServerIronADX(config)#server source-ip 192.168.1.5 255.255.255.0 192.168.1.1

Syntax: [no] server source-ip ip-addr network-mask default-gateway

The default-gateway variable is required. By specifying "0.0.0.0" as a gateway, the system is going to use the ip default-gateway configuration for the default gateway. The gateway function will not actually be disabled for the interface.


Adding a source IP address 2

You can configure source IP addresses to enable the ServerIron ADX to communicate with routers and real servers in different subnets. For example, Figure 6 shows an example of a ServerIron ADX that uses both public and private source NAT addresses.

NOTEYou can define a combined total of 64 source-ip and source-nat-ip addresses on a ServerIron ADX running switch code. The source-ip command is not required on ServerIrons running router code.

FIGURE 6 ServerIron ADX configured with public and private source NAT addresses

The ServerIron ADX in this example is configured with three source IP addresses. Two of the addresses are in the subnets of the real servers and the third address is in the same subnet as the ServerIron ADX management address.

The software considers any address that is not within the following address ranges to be a public address. These address ranges are defined as private address ranges in RFC 1918:

• 10.0.0.0 – 10.255.255.255

• 172.16.0.0 – 172.31.255.255

• 192.168.0.0 – 192.168.255.255

You can also use the server source-ip command under a real server to designate the source IP address for Source NAT.

For example, to specify that traffic from remote real server R1 use 10.77.7.7 as its source IP address, enter the following commands.

ServerIronADX(config)#server remote R1 10.77.7.2ServerIronADX(config-rs-R1)#source-ip 10.77.7.7

If the ip-addr variable is not already configured as a source IP address on the ServerIron ADX (with the server source-ip command), an error message is displayed.


Source NAT2

The server source-ip configuration is primarily used to provide the ServerIron ADX with source IP addresses in subnets other than that of the Management IP address. You can configure source IP addresses in the same subnet as the management IP, and you can configure multiple source IP addresses within each subnet. This gives you multiple opportunities to specify multiple default gateways for each subnet. However, the ServerIron uses only one default gateway per subnet. The ServerIron ADX uses the following rules when using the default gateways you have configured:

1) If the server source-ip configuration is in the same subnet as the Management IP address (M-IP) then the ServerIron ADX will use the Management IP address (M-IP) default gateway (the IP address you have configured with the ip default-gateway command) and ignore any other default gateway that you would have configured at the end of the server source-ip command. In the following example, the ServerIron will use only 192.168.1.254 as a gateway and will ignore 192.168.1.253.

server source-ip 192.168.1.11 255.255.255.0 192.168.1.253ip address 192.168.1.10 255.255.255.0ip default-gateway 192.168.1.254

2) If you configure multiple server source-ip addresses in a subnet different from the Management IP address's, then the ServerIron ADX will use the gateway that you configure at the end of the first server source-ip command. In the following example, the ServerIron ADX will use 192.168.1.254 as the gateway for all packets from 192.168.1.10 and 192.168.1.11 and also uses 192.168.2.254 as the gateway for all packets from 192.168.2.10 and 192.168.2.11. The ServerIron ADX will ignore 192.168.1.253 and 192.168.2.253.

server source-ip 192.168.2.10 255.255.255.0 192.168.2.254server source-ip 192.168.2.11 255.255.255.0 192.168.2.253server source-ip 192.168.1.11 255.255.255.0 192.168.1.253ip address 192.168.1.10 255.255.255.0ip default-gateway 192.168.1.254

The server source-ip configuration is only applicable when ServerIron ADX is using the switch code. If you need to have a different gateway for each destination network (for example, if you have your remote real servers split between multiple subnets, with each subnet behind a different router, and each of these routers directly connected to the ServerIron ADX), Brocade recommends that you use router code instead of switch code.

Source NATSource NAT configuration is useful where a ServerIron is connected in one-armed mode; for example where it is connected to the network infrastructure through an uplink as shown in Figure 7.

In this situation the ServerIron ADX passes the source IP address of the client to a back-end application server. If these servers have a direct path to the client, (as would be the case in one-armed design) the response will bypass the ServerIron ADX in the return path. This bypass breaks the traffic flow because the client sees the response coming from the IP address of the real server, instead of the IP address of the virtual server.

With Source NAT configured, a ServerIron ADX replaces the IP address of a client IP with the IP address of the ServerIron ADX in request packets forwarded to the real server. This action forces the real server to forward replies to the ServerIron ADX instead of bypassing it.


Source NAT 2

Figure 7 provides an example of what can occur when a real server has a path back to a client that bypasses a ServerIron ADX without Source NAT enabled as described in the following.

1. A request from the Client arrives at the ServerIron through a Layer 2 switch.

2. The ServerIron translates the VIP IP address to the IP address of the real server and forwards the request to the real server.

3. The real server sees the request coming from the IP address of the client and replies back directly through the Layer-2 switch bypassing the ServerIron.

4. The Client sees the response coming from an unknown IP address (other than the one that it sent the request to) and drops the packet.

FIGURE 7 Scenario without source NAT configured

In Figure 8 the traffic flow of the configuration is changed by enabling Source NAT as described in the following:

1. A request from the Client arrives at the ServerIron through a Layer 2 switch.

2. The ServerIron translates the VIP IP address to the IP address of the real server, replaces the IP address of the client with it’s own IP address and forwards the request to the real server.

3. The real server sees the request coming from the IP address of the ServerIron and replies back through the Layer 2 switch to the ServerIron.

4. The ServerIron translates the IP address of the real server to the VIP IP address and replies to the client.

FIGURE 8 Scenario with source NAT configured


Source NAT2

Source NAT can be configured either globally or per real server as described in the following sections: “Enabling source NAT globally” and “Enabling source NAT on a real server”.

Enabling source NAT globallySource NAT allows the ServerIron ADX to use a specific source IP address as the source for sending packets to real servers, which is useful for operating in a multinetted environment. You can enable source NAT globally or locally on individual real servers. If you enable source NAT globally, the feature applies to all real servers. If you enable the feature locally, the ServerIron ADX performs source NAT only for those real servers. Other locally-attached real servers, on which source NAT is not enabled, must be in the same subnet as the ServerIron ADX.

To enable source NAT globally, enter the following command.

ServerIronADX(config)#server source-nat

Syntax: [no] server source-nat

On a ServerIron ADX running switch code, you must also configure a source IP address. These ServerIron ADXs use source NAT to translate the management IP address in the source field of the IP packet into the source IP address you configure. Refer to “Minimizing source-IP and source-NAT-IP requirements for large deployments” on page 59. Refer to “Web hosting with ServerIron ADX and real servers in different subnets” on page 534 for an example of the type of configuration in which you need to use Source NAT.

By default, you can define a total of 64 source-ip and source-nat-ip addresses on ServerIron ADX devices running switch code. You can can increase the maximum supported SNAP IP addresses from 64 to 128 separately for both IPv4 and IPv6. For more information, refer to “Configuring maximum source-NAT IP addresses.”

The source-ip command is not required on ServerIrons running router code.

NOTEin a system with a large number of barrel processors (BP), the usable source NAT ports are limited. The larger the number of BPs that a system has, the lesser number of Source ports available for the BP. It is suggested that you use the “Enabling Port Allocation” feature when all 64 Source IPs are used up. Refer to “Enabling port allocation per real server for source IP” on page 60 and “Enabling port allocation per real server for source NAT IP” on page 60 for details.

NOTEWhen source NAT is enabled for FTP traffic, the ServerIron ADX only supports one mode for an established connection. This means that a user cannot toggle between active and passive mode for an existing FTP connection.

NOTEFor Router (R) code, the ServerIron ADX uses the Interface or VE address to do source NAT by default. No user action is needed. Optionally, you can define source NAT IP addresses if they are required. You can define total of 64 Interface or VE and source NAT IP addresses. Interface or VE addresses do not exist on Switch (S) code.

If you are configuring a pair of ServerIron ADXs for hot-standby (active-standby) HA and you want to use the same source IP address on each ServerIron ADX, use the server source-nat-ip command instead.


Source NAT 2

NOTEIf there are sessions that are currently using the source-nat-ip address and you delete that IP address, then you should wait till all the sessions are deleted before using the server source-nat-ip command with the deleted address or before a reload of the ServerIron ADX.

Enabling source NAT on a real serverSource NAT allows the ServerIron ADX to use a source IP address as the source for packets sent to the real server.

Source NAT allows the ServerIron ADX to be in more than one subnet. If the real server and the ServerIron ADX are in different subnets and not connected by a router that is multinetted, enable source NAT on the real server.

If you enable source NAT on a real server, the feature applies only to the server. You also can enable source NAT globally. Refer to “Enabling source NAT globally” on page 56.

To enable source NAT on a real server, enter commands such as the following.

ServerIronADX(config)#server real-name bertoServerIronADX(config-rs-berto)#source-nat

Syntax: [no] source-nat

Source NAT is disabled by default.

Configuring a shared source IP address for NATUse the server source-nat-ip command to divide the ports used for source NAT for a source IP address.

In a hot-standby (active-standby) HA configuration, this command configures a shared source IP address for NAT. Enter the same command with the same source IP address on each of the ServerIron ADXs. The address is active only on one ServerIron ADX (the ServerIron ADX that is currently active) at a time.

NOTEThis command applies only to hot-standby (active-standby) HA configurations. If you are configuring a shared source IP address for use by the real servers as their default gateway, use the server source-standby-ip command address instead. The gateway parameter is required.

To configure a shared source IP address, enter the command such as the following.

ServerIronADX(config)#server source-nat-ip 10.10.10.5/24 0.0.0.0 port-range 2

Syntax: [no] server source-nat-ip ip-addr ip-mask default-gateway port-range 1 | 2

The default-gateway variable is required. If you do not want to specify a gateway, enter "0.0.0.0".

The port-range parameter specifies which port range this peer uses for source NAT for this source IP address.Specify 1 for the lower port range or 2 for the upper port range. The peer using the upper port range is the owner of the source IP address. After you enter this command, ownership of the source IP address is negotiated between the peers. There must be a Layer 2 connection between the two ServerIron ADXs.


Source NAT2

Displaying Information about the Shared Source IP Address

To display information about the source IP address, enter the command such as the following.

Syntax: show server source-nat-ip ip-addr

Configuring shared source NAT IP addresses within a VIP groupUse the source-nat-ip command to configure shared source NAT IP addresses within a VIP group for Symmetric Active-Standby HA. In a Symmetric Active-Standby HA configuration, the shared source NAT IP addresses track the VRRP state to determine the active ServerIron ADX for a given source NAT IP address.

To configure a shared source NAT IP address within a VIP group, enter commands such as the following.

ServerIronADX(config)#server vip-group 1ServerIronADX(config-vip-group-[1])#source-nat-ip 10.10.10.3

Syntax: source-nat-ip ip-addr

The ip-addr variable is the shared source NAT IP address.

Source NAT to packets from specified source IP addressesBy default, if you configure the ServerIron ADX to apply source NAT for a real server, it is applied to all traffic for the real server. You can configure the ServerIron ADX to apply source NAT for a real server to traffic from specified source IP addresses.

To do this, you create an ACL, then specify the ACL in the source NAT configuration of the real server. When a flow is sent to the VIP, if the ACL specifies a permit action for the flow’s source IP address, then source NAT is performed on traffic in the flow.

For example, the following commands create an ACL that permits traffic from network 192.168.0.0/16 and denies all other traffic.

ServerIronADX(config)#access-list 1 permit 192.168.0.0 0.0.255.255ServerIronADX(config)#access-list 1 deny any

In comparison, the source-nat access-list acl-id command configures source NAT on a real server to be performed on traffic whose source IP address is permitted by ACL 1.

ServerIronADX(config)#server real r1 10.10.10.10ServerIronADX(config-rs-r1)#source-nat access-list 1

Client subnet based source NATThe selection of source NAT IP addresses is based on configured client subnets. You can associate a client subnet with a particular source NAT, which is defined on the ServerIron ADX. You can also associate multiple client subnets with the same source NAT IP address, and the same client subnet to multiple source NAT IP addresses. (These association type allow the clients to be load-balanced to real servers belonging to different subnets, and the source NAT IP address selected should belong to the same subnet as the real server).


Source NAT 2

When a client belonging to a configured subnet makes a new connection request, the source NAT IP address list corresponding to that client’s subnet is retrieved. Out of this list, a source NAT IP address is selected that is in the same subnet as the selected real server. If the selected source NAT IP address runs out of source ports, the ServerIron tries to use the next available source NAT IP address for that client’s subnet. The source-nat-ips that have been defined only for that client subnet will be used

To configure this feature, enter the following command.

ServerIronADX(config)#server source-nat 192.168.2.10 10.10.6.1

Syntax: server source-nat client-subnet source-ip

Enter the IP address to which the client belongs for client-subnet.

Enter the source NAT IP address of the subnet with which you want to associate the client’s subnet. The source NAT IP address you enter must be configured on the ServerIron.

Minimizing source-IP and source-NAT-IP requirements for large deploymentsIn previous implementations for earlier ServerIron ADX products, when source-ip or source-nat-ip is defined, the total number of 64K ports (of which some are reserved for internal use) per IP address are allocated and shared across all real servers. Each real server will only use portion of the entire port pool. As a result, the number of connections that the system can handle is limited by the number of source-ip or source-nat-ip defined on the system multiplied by the maximum port pool per IP.

As global port pool is shared by all real servers, the supply of ports can be quickly exhausted. Defining of additional source-ip or source-nat-ip may not always be feasible. The release 10.2.01 enhances this functionality and effectively conserves IP addresses.

In this implementation, the port pools are not shared globally but are allocated to each real server and each real server is able to use the entire pool by itself.

This feature is recommended for deployments with large numbers of real servers, which can lead to a shortage of ports and necessitate configuration of additional source IPs and source NAT IPs.

NOTEThis enhancement only applies to the server source-ip and server source-nat-ip. It is not applicable to source-ip and source-nat-ip addresses used for SSL.

NOTEYou need to write memory and reload after you configure this feature.


Source NAT2

NOTEIf source-ip and source-nat-ip are configured for the same subnet, then the source-nat-ip is given a higher priority. In the router case, the interface IPs are programmed as source-ips on the BP. The IP that matches the default gateway is given preference in the router case. As a result, if you configure the source-nat-ip in a subnet different than the gateway remote servers that are defined on the ServerIron ADX, then this source-nat-ip must not be used. You should take this into account during network design. For example, if you want to keep using the same IP 10.4.4.101 as source-ip, but change old source-ip feature to new source-ip port-alloc-per-real. You need to perform the following steps in order:

1. Bring traffic that hit 10.4.4.101 to zero.2. No server source-ip 10.4.4.101 255.255.255.0.0.0.0.03. Server source-ip 10.4.4.101 255.255.255.0.0.0.0.0 per-alloc-per-real

To enable this feature, use the port-alloc-per-real keyword along with server source-ip or server source-nat-ip commands.

• “Enabling port allocation per real server for source IP”

• “Enabling port allocation per real server for source NAT IP”

Enabling port allocation per real server for source IP

To enable port allocation per real server for the source IP address, use the following command:

ServerIronADX(config)#server source-ip 10.157.22.28 255.255.255.0 10.157.22.1 port-alloc-per-real

Syntax: [no] server source-ip ip-addr ip-mask default-gateway [ port-alloc-per-real ]

NOTEPort allocation per real server cannot be configured if keepalive health checks are enabled for the virtual server port.

Enabling port allocation per real server for source NAT IP

To enable port allocation per real server for the source NAT IP address, use the following command.

ServerIronADX(config)#server source-nat-ip 10.10.10.5 255.255.255.0 0.0.0.0 port-range 2 portalloc-per-real

Syntax: [no] server source-nat-ip ip-addr ip-mask default-gateway port-range 1|2 [port-alloc-per-real]

NOTEThe ServerIron ADX does not use the source-nat-ip default-gateway variable for remote server health checks as well as for forwarding SLB traffic to the remote server.


Source NAT 2

NOTEYou should not enable or disable this functionality while the IP addresses are in use by the traffic flow. You must bring the traffic level to zero using this IP address or remove the command and redefine it.

You should not enable or disable this functionality while the IP addresses are in use by the traffic flow. You must bring the number of traffic flows utilizing this IP address to zero or remove the command and redefine it.

As an example, for changing from statement #1 to statement #2 below, either bring the traffic level to nil or negate the command first using the no server command and then re-define it.

statement #1: server ... port-range 1

statement #2: server ... port-range 1 port-alloc-per-real

NOTEThe maximum number of configured source-nat-ip addresses that can be supported by the “port allocation per real server” feature is 16.

Logging port exhaustion message

You can configure the ServerIron to log a message when a source IP or source NAT IP runs out of ports.

Syntax: [no] source-ip-log

IPv6 Source NAT ACL SupportThe ServerIron ADX release 12.4.00e introduces the IPv6 Source-NAT (SNAT) ACL support. This feature allow users to configure a source NAT access list for a real server by specifying the acl_name variable of the IPv6 ACL.

By default, if you configure the ServerIron ADX to apply source NAT for a real server, it is applied to all traffic for the real server. You can configure the ServerIron ADX to apply the source NAT for a real server to traffic from specified source IP addresses.

To do this, you need to create an access-list (ACL), then specify the ACL in the source NAT configuration of the real server. When a flow is sent to the VIP, if the ACL specifies a permit action for the flow’s source IP address, the source NAT is performed on the traffic in the flow.

Starting with the ServerIron ADX release 12.4.00e, the source-NAT access-list feature is available for IPv6 addresses in addition to IPv4 addresses.


Source NAT2

Configuring IPv6 Source NAT ACL

To configure the IPv6 Source NAT ACL feature, use the source-nat ipv6 access-list command to add support to the real servers in the traffic mode as shown below:

ServerIronADX(config)#server real-name rs10ServerIronADX(config-rs-rs10)#source-nat ipv6 access-list acl_10

Syntax: [no] source-nat ipv6 access-list acl_name

The acl_name variable is the name of the IPv6 access-list.

Example

The following example is the configuration of the IPv6 source NAT ACL feature on the ServerIron ADX for real server rsv6 with the IPv6 ACL myacl.

ServerIronADX(config)#ipv6 access-list myaclServerIronADX(config-ipv6-access-list myacl)# permit ipv6 3000::/64 anyServerIronADX(config-ipv6-access-list myacl)# exitServerIronADX(config)# server real rsv6ServerIronADX(config-rs-rsv6)# source-nat ipv6 access-list ASCII string Access List Name for IPv6ServerIronADX(config-rs-rsv6)# source-nat ipv6 access-list myaclServerIronADX(config-rs-rsv6)# end

NOTEThe CLI will prevent users from configuring IPv6 SNAT access list for IPv4 real servers and IPv4 SNAT access list for IPv6 real servers.

Increasing the maximum of source-NAT IP addressesBy default, the ServerIron ADX supports a system maximum of 64 addresses. You can increase the number of address to a system maximum of 128. With an increase to 128 address, the ServerIron ADX could have an impact in performance. With source-NAT caching per real server, performance would not be impacted.

Configuring maximum source-NAT IP addresses

By default, the ServerIron ADX support 64 source-nat-ip addresses. You can configure separately a maximum of 128 source-NAT IP addresses for IPv4 and IPv6. The total number of allowed source-NAT IPs is the sum of the maximum IPv4 and maximum IPv6 source-NAT IPs configured.

NOTEYou must reboot the ServerIron ADX for the change to take effect.

To increase the maximum number of IPv4 addresses, use the system-max source-ip command.

ServerIronADX(config)# system-max source-ip 100ServerIronADX(config)# write memoryServerIronADX(config)# exitServerIronADX# reload


Source NAT 2

To increase the maximum number of IPv6 addresses, use the system-max source-ip6 command.

ServerIronADX(config)# system-max source-ip6 100ServerIronADX(config)# write memoryServerIronADX(config)# exitServerIronADX# reload

Syntax: [no] system-max source-ip max_addresses

Syntax: [no] system-max source-ip6 max_addresses

The max_addresses variable specifies maximum source-NAT IP addresses. Enter a number from 0 to 128. The default maximum value is 64.

NOTEWhen you increase the maximum number of source-NAT IP addresses to 128, the ServerIron ADX looks up to 128 source-NAT IP addresses for every new connection and impacts the ServerIron ADX performance. To resolve this impact, enable the source-NAT caching feature. For more information, refer to “Enabling source-NAT caching.”

Use the no form of this command to reset the default value.

Displaying maximum source-NAT IP addresses

To display the maximum source-NAT IPv4 and IPv6 addresses, use the show default values command.

ServerIronADX(config)# show default valuesSystem Parameters Default Maximum Currentsource-ip 64 128 64source-ip6 64 128 64

Syntax: show default values

Enabling source-NAT caching

By default, source-NAT caching is disabled. The ServerIron ADX performs lookups to the configured system maximum of source-NAT IP addresses for every new connection to a real server. If you increase the system maximum number of source-NAT IP addresses to 128, the ServerIron ADX performance is impacted while looking up to 128 source-NAT addresses for every new connection.

To avoid source-nat IP lookups for the same server every time, enable source-NAT caching. When caching is enabled, the ServerIron ADX caches the address for the real server and use the address for subsequent sessions to same server. For every new connection made to the same real server, the ServerIron ADX uses the same source NAT IP address until it exhausts all the free ports.

To enable the source-NAT caching for all real servers globally, use the server source-nat cache enable command.

ServerIronADX(config)# server source-nat cache enable

To disable the SNAT caching for all the servers globally and reset the default behavior, use the server source-nat cache disable command.

ServerIronADX(config)# server source-nat cache disable

Syntax: server source-nat cache enable | disable


Remote server2

Disabling two-level CAM distribution on IPv6-optimized source-NAT entries

By default, IPv6 source-NAT entries use external Content Access Memory (CAM) lookups based on port distribution. When IPv6 optimization is enabled on the ServerIron ADX, the IPv6 source-NAT entries use internal CAM lookups based on two-level CAM distribution.

To disable two-level CAM distribution on IPv6 source-NAT entries when IPv6 optimization is enabled, and use port-based CAM distribution, use the server source-nat optimized-mode-disable command.

ServerIronADX(config #server source-nat optimized-mode-disable

Syntax: server source-nat optimized-mode-disable

NOTEThe ServerIron ADX has better performance if IPV6 optimization mode is enabled with two-level CAM distribution.

Remote serverIf the server is attached through one or more router hops, configure the server as remote. When you add a remote real server, the ServerIron ADX does not include the server in the predictor (load-balancing method). Instead, the ServerIron ADX sends traffic to the remote server only if all local real servers are unavailable. The server name is used to bind the server IP address, so that the real server name can be used to represent the server.

To configure a remote real server, enter a command such as the following.

Syntax: server remote-name name ip-addr

The name variable is the name of the remote server. Enter an alphanumeric string of up to 42 characters.

This command is used in conjunction with the server load balancing feature on the ServerIron ADX switch.

Refer to “Unbinding all application ports from virtual servers” on page 158.

Sticky and concurrent connections

Configuring sticky portsBy default, the ServerIron ADX sends a client’s request to the next available real server based on the load balancing method. This is true regardless of whether the client has already sent a request for the same application. If you want the ServerIron ADX to send all of a client’s requests for a given application to the same real server during a client’s session with the server, configure the application port to be sticky.

Both the track port and track port group methods of application port grouping require you configure the application ports involved as sticky ports. For more information, see “Application port grouping” on page 73.


Sticky and concurrent connections 2

NOTEFor servers that use passive FTP in a DSR configuration, configure the FTP ports to be both sticky and concurrent.

NOTEWhen a default port is configured as “sticky”, the ServerIron ADX creates the sticky session for port default (65535). Any new connection will follow the sticky session for port default. If sticky is configured for a specific port as well as port default, sticky for the specific port will follow the sticky session for the specific port regardless of the sticky session for port default.

For a configuration example and more information, refer to “TCP/UDP application groups” on page 531.

To configure a TCP or UDP port as sticky, use the port sticky command when you add that port to a virtual server:

ServerIronADX(config)#server virtual-name-or-ip v1 10.157.22.1ServerIronADX(config-vs-v1)#port 80 sticky

In this example, the commands configure HTTP (port 80) as sticky.

Syntax: [no] port tcp/udp-port sticky

Configuring stickiness based on client’s subnetThe sticky function causes the ServerIron ADX to send all of a client’s requests for a given application to the same real server during the client’s session with the server. By default, the stickiness is based on the client's IP address. You can configure the ServerIron ADX to base the stickiness on the client’s subnet, rather than IP address. All requests originating from a specific subnet for a given application are sent to the same real server.

For example, to send all HTTP requests originating from a given subnet to the same real server, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip vs1 10.10.10.10ServerIronADX(config-vs-vs1)#port httpServerIronADX(config-vs-vs1)#port http client-subnet-sticky prefix-length 24

Syntax: [no] port portnum client-subnet-sticky { prefix-length prefix-length} |{ subnet-mask client-subnet-mask}

In this example, client requests from subnet 192.168.9.x would go to the same real server. Sub-net sticky connections are aged out according to the sticky age setting, in the same way regular sticky connections are aged out.

The port sticky and port client-subnet-sticky commands cannot be configured together on the same port on the same virtual server.

The SSL port is configured as sticky by default, and the CLI will not allow you to configure port client-subnet-sticky on an SSL port of a virtual server. As a work around, you must first disable the sticky function before configuring port ssl client-subnet-sticky on a virtual server.

ServerIronADX(config)#server virtual-name-or-ip vs1 10.10.10.10ServerIronADX(config-vs-vs1)#port sslServerIronADX(config-vs-vs1)#no port ssl stickyServerIronADX(config-vs-vs1)#port ssl client-subnet-sticky prefix-length 24


Sticky and concurrent connections2

Setting the sticky ageYou can age out inactive sticky server connections. A connection is sticky if you configure the ServerIron ADX to send successive requests from the same client for the same application port to the same real server, instead of load balancing the requests to different real servers.

Sticky connections are defined on a virtual server port of an SLB switch when a service request by a client mandates a series of sequential TCP or UDP port connections to be served by the same real server. For example, if a client is accessing dynamically generated pages, the client must consistently attach to the same server, otherwise the state information will be lost.

The sticky age is a global setting applying to all virtual servers; you can also set the sticky age for an individual virtual server. The sticky age for the individual virtual server overrides the global setting.

To set the sticky age globally, enter a command such as the following.

ServerIronADX(config)#server sticky-age 20

To set the sticky age for an individual virtual server, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip v1ServerIronADX(config-vs-v1)#sticky-age 20

Syntax: [no] server sticky-age minutes

The minutes variable is the sticky age in minutes. Enter an integer from 2 to 60 . The default is 5 minutes.

Preserving a sticky session when the health check is downBy default, the ServerIron ADX removes a sticky session in a session table when the health check is down. The ServerIron ADX ages out the session within the configured time of the sticky multiplier after a health check is down. When a health check goes down on the standby ServerIron ADX only, the standby ServerIron ADX ages out the session within one minute while the active ServerIron ADX keeps the session. When a HA failover occurs, the new active ServerIron ADX may not have the sticky session and may forward the packet to a different real server after the health check is up again.

You can configure the ServerIron ADX to preserve a sticky session in a session table when the health check is down. This is useful when you have High Availability (HA) configurations and you want to maintain the session with another available real server.

To preserve a sticky session when the health check is down, use the server allow-sticky health-check-down command.

ServerIronADX(config)# server allow-sticky health-check-down

Syntax: [no] server allow-sticky health-check-down

This command takes effect immediately. After the command is executed, when the ServerIron ADX receives a packet that matches the sticky session, the ServerIron ADX updates the sticky session to the next available real server due to the health check being down.



Allowing sticky portsYou can configure the ServerIron ADX to continue using a sticky port (a persistent connection) even if you have entered a command to unbind the port or the port is disabled.

When you unbind an application port from a server, the ServerIron ADX temporarily places the port in the aw_unbnd (awaiting unbind) state. If you delete an application port, the ServerIron ADX temporarily places the port in the aw_del (awaiting delete) state. These temporary states allow open sessions on the port to be completed before the port is unbound or removed.

By default, when the ServerIron ADX receives a new request associated with a sticky port in the aw_unbnd state, the ServerIron ADX establishes the session on another real server, not the real server from which you are unbinding the port.

You can configure the ServerIron ADX to accept new sessions for the same real server for a sticky port, even under the following conditions:

• The real server port is in the aw_unbnd state.

• The real server port is in the aw_del state.

• The real server port is disabled.

To do so, enter the following command.

ServerIronADX(config)#server allow-sticky

Syntax: [no] server allow-sticky [refresh-age]

The refresh-age option resets the age of a sticky session on the port whenever a new connection associated with the sticky port is established. This parameter ensures that the session stays up indefinitely until it is no longer needed.

By default, the ServerIron ADX does not reset the age of the session when new connections are established. Instead, the session times out after the sticky age expires.

If you use the refresh-age option, the ServerIron ADX resets the age of the session to the value of the sticky age. For example, if the sticky age is five minutes (the default), when the ServerIron ADX establishes a new session on the sticky port, the ServerIron ADX resets the age time for the session to five minutes. Each time the ServerIron ADX receives another connection request associated with the sticky session, the ServerIron ADX resets the session age again.

Increasing the sticky-age per VIP longer than 60 minutes Several applications require sticky age to be longer than the 60 minute global maximum that is configured using the server sticky-age command as described in “Setting the sticky age” on page 66. This might occur where a client connects in the morning and requires connectivity throughput the day.

There are also situations where you may want to configure a different value per virtual server. The following command allows you to apply a multiplier value to the global sticky-age value for a specific virtual server.

ServerIronADX(config)#server virtual-name-or-ip vs1 10.10.10.10ServerIronADX(config-vs-vs1)#sticky-age-multiplier 5

Syntax: sticky-age-multiplier multiplier-value



The multiplier-value variable is a numerical value in the following range: 2 to 120. This value is used to produce a sticky-age value for the virtual server it is configured under that is a multiple of the value configured globally for the ServerIron as described in “Setting the sticky age” on page 66. For example, if the sticky age is configured to be 20 minutes, and the sticky-age-multiplier to be 40, then the actual sticky age of the sticky sessions for the server will be 20x40= 800 minutes.

Please note that even though the sticky-ages are multiplied, the show session command will still only show ordinary age of the sticky sessions. The difference is that the age is incremented in a slower pace when multiplier is applied. For example if the sticky-age-multiplier is configured to be 40, the age counter in the session table is incremented once in 40 minutes instead of 1 minute.

NOTEYou can remove the multiplier by using the sticky-age-multiplier 1 or no sticky-age-multiplier number command.

Sticky connection return from backup server to primaryYou can designate real servers as primary servers or backup servers. A primary server is used by the ServerIron ADX when load balancing client requests for an application. A backup server is used by the ServerIron ADX only if all the primary servers are unavailable for the requested application.

In a configuration where one real server is configured as a primary server and another is configured as a backup, the virtual server can have the sticky option enabled, which ensures that new connections are sent to the primary server, and a sticky session to a given port is created that points to that primary server.

If the primary server goes down, new connections are sent to the backup server, and a sticky session to the port is created that points to the backup server. The sticky session to the (inoperative) primary server is deleted. When the primary server becomes operative again, since the sticky session to the backup server is still valid (that is, it has not aged out), new connections to the port are still sent to the backup server. This is the default behavior.

You can optionally configure the ServerIron ADX to send new connections for the port to the primary server when it comes back up, even though there is a sticky session to the backup server.

To do this for the DNS port on virtual server v1, enter the following commands.

ServerIronADX(config)#server virtual-name-or-ip v1 192.168.9.210ServerIronADX(config-vs-v1)#port dns lb-pri-serversServerIronADX(config-vs-v1)#port dns stickyServerIronADX(config-vs-v1)#port dns active-primary-overide-sticky

Syntax: port port active-primary-overide-sticky

When the active-primary-overide-sticky keyword is configured, if the primary server goes down and then comes back up, any new connection to the DNS port is sent to the primary server. The old sticky session to the backup server is deleted, and a new sticky session to the primary server is created.



Group sticky: Layer 4 SLB to server groupLayer 4 load balancing to server groups is performed through a Group Sticky function. This sticky behavior supports Group Sticky and Group Failover functionality.

Enabling group sticky

The group sticky feature enables sticky connections to be load balanced among servers in the same group. Without this feature, normal sticky behavior always sends a specific client IP to a specific server. Group Sticky is useful when the server farm is grouped into clusters, and each cluster has servers with replicated (mirrored) content.

To enable Group Sticky, use the port type group-sticky command.

Configuration example

FIGURE 9 Group sticky sample topology

Figure 9 shows two server groups: group-id 1 1 and group-id 2 2. The configured VIP is serving the clients and load balancing traffic across the servers in their respective groups.

When a client first enters the system, the ServerIron ADX inspects the defined groups, predictors, and chooses a server within a group to create a sticky session. When a new connection comes in from the same client and group sticky is configured, the ServerIron ADX will find all the servers belonging to the group and will load balance among the servers.



Perform the following steps.

1. Set up the real servers and group IDs. The rs1 and rs2 are in group 1. The devices Web1, Web2, and Web3 are in group 2.

server real rs1 10.20.1.40 port http port http url "HEAD /" port http group-id 1 1

server real rs2 10.20.1.41 port http port http url "HEAD /" port http group-id 1 1

server real Web1 10.20.1.42 port http port http url "HEAD /" port http group-id 2 2



2. On the VIP, ensure the minimum required commands for Group Sticky are present: port type group-sticky and port type sticky. If stickiness is not configured, load balancing among the group will not work.

ServerIronADX(config-vs-v1)#server virtual-name-or-ip vip1 10.40.1.10ServerIronADX(config-vs-vip1)#predictor round-robinServerIronADX(config-vs-vip1)#port http sticky !(or port http client-subnet-sticky)ServerIronADX(config-vs-vip1)#port http group-stickyServerIronADX(config-vs-vip1)#bind http rs1 http rs2 http Web1 http Web2 httpServerIronADX(config-vs-vip1)#bind http Web3 http

Once a group sticky session is created, all subsequent traffic will be load balanced across the group. The first incoming sticky session will go to a real server in group 1. All subsequent connections will also go to group 1.

If multiple clients are in the same subnet, then use the port http client-subnet-sticky command instead of port http sticky. The group sticky behavior will apply itself to the client-subnet-sticky.

NOTEWhen a real server’s port is part of two groups, the group-sticky feature takes the first listed group ID only, if the first connection is load balanced to this server.



3. Identify what server the sticky session is pointed to. In the example below, the sticky session was originated from the client 10.30.1.1 to the VIP 10.40.1.10 using real server rs1. All the traffic to/from the client is being load balanced across the group (group-id 1 1) to which the real server rs1 belongs. Enter the show session all 0 command (at the BP console) such as the following.

NOTEIn most cases, an "S-port" of value "0" indicates a sticky session. Regardless of the source port (S-port) of the connection, the sticky session will stick to Src-IP 10.30.1.1, Dst-IP 10.40.1.10, and D-port 80 in the example.

To clear a sticky session, use the clear server session command.

Enabling group sticky failover

Normal Group Sticky behavior sends connections to a group of servers. When an entire server group is unreachable, Group Sticky Failover sends connections to a different reachable group. The sticky session is removed from the unreachable group; a connection request is forwarded to a new group, and a new sticky session is then formed with that group.

To enable group sticky failover, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip vip1 10.40.1.10ServerIronADX(config-vs-vip1)#predictor round-robinServerIronADX(config-vs-vip1)#port http stickyServerIronADX(config-vs-vip1)#port http group-stickyServerIronADX(config-vs-vip1)#port http group-sticky-failoverServerIronADX(config-vs-vip1)#bind http rs1 http rs2 http rs3 http rs4 httpServerIronADX(config-vs-vip1)#bind http rs5 http

Use the required port http group-sticky-failover command in addition to port http sticky and port http group-sticky commands. The group-sticky-failover option alone will not work.

Syntax: port type group-sticky-failover

NOTEThe server sticky-age command can also be applied to a sticky group.

ServerIronADX#rconsole 1 1ServerIronADX 1/1#show session all 0Session Info:

Flags - 0:UDP, 1:TCP, 2:IP, 3:INT, 4:INVD, H: sessInHash, N: sessInNextEntry

Index Src-IP Dst-IP S-port D-port Age Next Serv Flags===== ====== ====== ====== ====== === ==== ==== =========0 10.30.1.1 10.40.1.10 0 80 59 000000 rs1 SLB3 H



Enabling a concurrent portThe concurrent feature allows a client to have sessions on different application ports on the same real server at the same time. When you enable an application port to be concurrent, the real server can open additional (“concurrent”) TCP or UDP sessions with the client using arbitrary TCP or UDP port numbers.

Although the concurrent connections attribute is similar to application groups, application groups apply to specific TCP or UDP ports that you configure on the virtual server.

NOTEFor servers that use passive FTP *in DSR configuration*, configure the FTP ports to be both sticky and concurrent.

To enable an application port to be concurrent, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip v1 10.157.22.1ServerIronADX(config-vs-v1)#port 80 concurrent

Syntax: [no] port tcp/udp-port concurrent

Configuring virtual sourceIn a typical configuration, a client’s IP address remains the same throughout the client’s session with a virtual server. However, in some configurations where a proxy is used for the clients before the client traffic reaches the ServerIron ADX, the client’s IP address can be different for each request. To configure session persistence in a proxy environment, configure a standard IP ACL containing the addresses, then use the Virtual Source feature.

When you configure the Virtual Source feature, the ServerIron ADX sends all client traffic from a specified range of IP addresses to the same real server for the application ports you specify. To specify the IP addresses, configure a standard IP ACL. Use this command in configurations where a proxy device allocates IP addresses to client traffic before sending the traffic to the VIP. In some configurations, the proxy device assigns different IP addresses to traffic from the same client. Unless you configure the addresses to go to the same real server, the ServerIron ADX might load balance the client traffic to different servers. This makes applications that require continued access to the same real server unusable.

To configure the Virtual Source feature, enter commands such as the following.

ServerIronADX(config)#access-list 1 permit 10.157.22.0ServerIronADX(config)#server virtual-name-or-ip fromproxy 10.1.1.1ServerIronADX(config-vs-fromproxy)#port 80 sticky-acl 1

Syntax: [no] access-list num deny | permit source-ip | hostname wildcard [log]

or

Syntax: [no] access-list num deny | permit source-ip/mask-bits | hostname [log]

Syntax: [no] port tcp/udp-port sticky-acl num


Application port grouping 2

NOTEThis feature is different from the sticky feature, which you can associate with ports on the virtual server level. The sticky attribute ensures that subsequent packets from the same client during the same TCP session go to the same real server. In this case, the ServerIron ADX knows the packets are from the same client based on the source IP address. When a proxy is used, subsequent packets from the same client can have different IP addresses.

For standard IP ACL configuration information, refer to the “Configuring Standard ACLs” section in the “Access Control Lists” chapter of the ServerIron ADX Security Guide.

Application port groupingThe track port and track port group methods of TCP/UDP application grouping are similar. In both configurations, the ServerIron ADX sends all client requests for ports within a specific set of application ports to the same real server. The two methods differ in the following way:

• In a track port configuration, the tracking applies only to the primary port, which is the first port in the list of track ports. If the client requests one of the other applications (one of the applications that is tracking the primary application) first, ServerIron ADX tracking does not apply.

• In a track port group configuration, the ServerIron ADX sends client requests for applications within a group to the same real server regardless of which application the client requests first.

The track and track-group commands for a port are mutually exclusive.

Tracking primary portsYou can configure the ServerIron ADX to send all client requests for a specific set of TCP or UDP ports to the same real server as a “primary” TCP or UDP port grouped with the other ports.

The primary TCP or UDP port can be grouped with up to four additional TCP or UDP ports. Once the ServerIron ADX sends a client request for the primary port to a real server, all subsequent requests from the client for ports grouped with the primary port go to the same real server. For a configuration example and more information, refer to “TCP/UDP application groups” on page 531.

Note that if any service port is down for a real server, any track ports on that real server are not considered for load balancing.

NOTEYou must configure all the grouped ports to be “sticky” and bind them to all real servers involved.

NOTEIf a client requests one of the ports that follows the primary port before requesting the primary port itself, the ServerIron ADX does not make the connection sticky. Only after the client requests the primary port does the ServerIron ADX make subsequent requests from the client for that port or ports that track the primary port sticky.

NOTEFor servers that use passive FTP in a DSR configuration, configure the FTP ports to be both sticky and concurrent.


Application port grouping2

To configure a TCP or UDP application group, enter the following commands.

ServerIronADX(config)#server virtual-name-or-ip v1 10.157.22.1ServerIronADX(config-vs-v1)#port 80 stickyServerIronADX(config-vs-v1)#port 23 stickyServerIronADX(config-vs-v1)#port 69 stickyServerIronADX(config-vs-v1)#track 80 23 69ServerIronADX(config-vs-v1)#bind 80 r1 80 r2 80ServerIronADX(config-vs-v1)#bind 23 r1 23 r2 23ServerIronADX(config-vs-v1)#bind 69 r1 69 r2 69These commands configure HTTP (port 80), Telnet (port 23), and TFTP (port 69) to be sticky.

Syntax: [no] track primary-port TCP/UDP-port [TCP/UDP-port [TCP/UDP-port [TCP/UDP-port]]]

Track port group functionIn a track port group, the ServerIron ADX sends client requests for applications within a group of ports to the same real server, regardless of which application the client requests first.

Up to eight ports can be grouped together using the track port group function. However, a port can be part of only one track port group. For a configuration example and more information, refer to “TCP/UDP application groups” on page 531.

Note that if any service port is down for a real server, the track port groups on that real server are not considered for load balancing.

NOTEEvery port in a track port group must be configured to be “sticky” and be bound to the real servers involved.

NOTEIf no track port group configured, the sticky session age is not refreshed if any data session exists. Only the data session's age will be refreshed if the connection is still alive.

NOTEIf a track port group is configured into the VIP (i.e. for two ports), the sticky session refreshes and will not expire as long as one of the ports has an alive session.

Configuring a track port group

To configure a track port group, enter commands such as the following:

ServerIronADX(config)#server virtual-name-or-ip v1 10.157.22.1ServerIronADX(config-vs-v1)#port 80 stickyServerIronADX(config-vs-v1)#port 69 stickyServerIronADX(config-vs-v1)#port 23 stickyServerIronADX(config-vs-v1)#track-group 80 69 23ServerIronADX(config-vs-v1)#bind 80 r1 80 r2 80ServerIronADX(config-vs-v1)#bind 23 r1 23 r2 23ServerIronADX(config-vs-v1)#bind 69 r1 69 r2 69ServerIronADX(config-vs-v1)#exit

In this example, the track-group command groups the HTTP port (80), TFTP port (69), and Telnet port (23) together. Whenever a client attempts to connect to a port within the port group, the ServerIron ADX ensures that all ports in the group are active before granting the connection.


Application port grouping 2

Syntax: [no] track-group TCP/UDP-port...

The sticky parameter makes the TCP or UDP ports sticky. The sticky parameter must be set for all ports in the group.

After the ServerIron ADX sends a client to a real server for any of these three ports, subsequent requests from that client for port HTTP, TFTP, or Telnet will go to the same real server.

Track port group health checks for real servers

ServerIron ADX enables you to configure track port groups for both virtual servers and real servers; thereby reducing the need to create large numbers of Boolean health checks.

You can track the health of multiple application ports under a real server definition. If the health of one of the application ports fails, the aggregated health will be marked as fail.

Track port group health checks co-exists with existing health checks and other features of the ServerIron ADX. If even one of the application ports under real server is not up, the track port group state will be down and the traffic will not be forwarded to any of the ports in the track port group.

A sample configuration is shown below.

ServerIronADX(config)#server real r1 10.1.1.1ServerIronADX(config-real-server-r1) port 80ServerIronADX(config-real-server-r1) port ftpServerIronADX(config-real-server-r1) port dnsServerIronADX(config-rsr1) hc-track-group 80 21 53

In this example, the ServerIron ADX now tracks health status for ports 80, 21, and 53. If any of these ports is down. the combined health would be marked as failed and the ServerIron will not use these ports for load balancing traffic.

Sample configurationserver real rs1 10.1.1.1port httpport 8081port 8082hc-track-group http 8081 8082

Here is the output of the show hc-track-group-state command for this feature.

ServerIronADX#show hc-track-group-stateReal Server track-group staters1 80 21 53 ACTIVE

Syntax: show hc-track-group-state

NOTEThe output of the above command may be truncated. For a complete output display, use the show hc-track-group-state detail command.

Here is an example output for the show hc-track-group-state detail command .

ServerIronADX#show hc-track-group-state detailStatus of health check track groups

Real Server: rs1Track-group: 80 8080 8081 8082State : DOWN


Primary and backup servers2

Real Server: rs2Track-group: 80 8080 8081 8082State : ACTIVE

Enabling track ports in a track port group to unbind

By default, when you unbind a port that is the lead port in a track port group, all the ports that track the lead port also are immediately unbound. This occurs even if a port is still active and has not completed the AW_unbind (awaiting unbind) state.

To configure the ServerIron ADX to allow track ports in a track port group to unbind gracefully after the unbinding of the track group’s lead port, enter the following command:

ServerIronADX(config)#server track-group-unbind-wait-all

Syntax: [no] server track-group-unbind-wait-all

NOTEIf a port is the master port of a track group, the port (master port itself) cannot unbound immediately if there is any outstanding sessions for any ports in that track group.

Primary and backup serversThe ServerIron ADX has the feature where the real server is either a primary server or a backup server based on how you added it:

• A primary server is used by the ServerIron ADX when load balancing client requests for an application. It is a locally attached server added using the server real-name-or-ip command or using the Web GUI equivalent.

• A backup server is used by the ServerIron ADX only if all the primary servers are unavailable for the requested application. It is remotely attached and added using the server remote-name command or using the Web GUI equivalent.

You can explicitly designate a server to be a primary server or a backup server, regardless of the command you used to add it. Therefore, a primary server or backup server can be locally attached or attached through a router.

In addition, this feature implements the primary and backup configuration on an individual VIP basis. You designate each backup server by changing the real server configurations. You do not need to designate the primary servers. You enable the feature in individual VIPs for individual application ports.

NOTEThe ServerIron ADX does not diffentiate between real and remote servers when the primary-backup feature is enabled. Traffic will be load balanced among primary servers (real or remote). When all primary servers are down, traffic will be load balanced among backup servers.

NOTEWithout the primary-backup feature enabled, traffic will be load balanced among real servers and when all real servers are down, traffic will be sent to remote servers.


Primary and backup servers 2

Figure 10 shows an SLB configuration that uses locally attached and remotely attached servers. The configuration also uses some of the servers as the primary load-balancing servers while using the other servers only as backups. Notice that one of the locally attached servers is a backup server while one of the remotely attached servers is a primary load-balancing server.

FIGURE 10 Servers configured as primaries and backups

By default, when this feature is enabled on a VIP and all the primary servers are unavailable, a VIP begins using the backup servers until a primary server becomes available again. When a primary server is available, the VIP uses the primary server instead. Optionally, you can configure a VIP to continue to use the backup servers even after the primary servers become available again.

To configure primary and backup servers, perform the following tasks.

1. Edit the configuration of each backup real server to designate the server as a backup.

NOTEYou do not need to designate the primary servers. The ServerIron ADX assumes that all servers you do not designate as backup servers are primary servers.

2. Enable use of the primary and backup servers in individual VIPs on individual application ports. Only the VIPs and application ports for which you enable the feature use it. The other application ports within the VIP, and the other VIPs, use the locally-attached servers (configured using the server real-name-or-ip command) as their primary servers and the remotely-attached servers (configured using the server remote-name command) as their backup servers.

Optionally, configure the individual applications on the VIPs to continue using the backup servers following a failover, instead of returning to the primary servers.



Designating a real server as a backupBy default, the virtual server uses the locally attached real servers as the primary load-balancing servers and uses the remotely attached servers as backups.

To designate a real server to be a backup server, enter the following command.

ServerIronADX(config-rs-R3)#backup

Syntax: [no] backup

In order for the backup functionality to operate, you must also apply the lb-pri-servers command.

Enabling a VIP to use the primary and backup serversTo enable a VIP to use the servers designated as backups only as backups, and use the other servers as the load-balancing servers, enter the following command at the configuration level for the VIP.

ServerIronADX(config-vs-VIP1)#port http lb-pri-servers

This command enables VIP1 to use the backup and primary servers for application port HTTP.

The port http lb-pri-servers command is needed for the backup functionality to operate, regardless of the real servers you have, local or remote. For example, even if all your real servers are local and you have one designated as backup, it will not be used as a backup unless you apply this command.

To configure the VIP and application port to continue using the backup servers even after the primary servers become available again, use the backup-stay-active parameter, as in the following example.

ServerIronADX(config-vs-VIP1)#port http lb-pri-servers backup-stay-active

Syntax: [no] port tcp/udp-port lb-pri-servers [backup-stay-active]

When configuring the backup-stay-active option, you might expect that all traffic will go to the backup server even when the primary comes back up. However, this may not be the case in some situations. The backup-stay-active feature is triggered by health check and works independently on each BP (i.e., the change in server selection logic of one BP is not reflected in the other BPs). Effectively, if there are no new connections on a BP during the phase when the Primary Server fails and recovers, new connections on that BP (after the Primary recovers) will still be forwarded to the Primary Server. But, if another BP receives new connections while the Primary is failed (and before it recovers), any new connections from that point on (for that BP) will always be forwarded to the Backup Server. Consequently, from the end-user perspective (or from MP view), you may see traffic going to both primary and backup servers (from different BPs).

Prior to the ServerIron ADX release 12.4.00c, selection of backup server was solely dependent on the timing of incoming client connection and was not tightly coupled with the system-level health of the primary and backup servers. In some rare events, this results in servicing of traffic by both primary and backup servers which is undesirable. Starting with the ServerIron ADX release



12.4.00c, additional checks are added to ensure that the client traffic is handled by either primary servers only or by the backup servers only at all times. You can use the show server backup-associated state command to see which server is currently active as shown in the following example.

Syntax: [no] show server backup-associated-state [vip-name] [application-port]

Configuration exampleThe example configures load-balancing shown in Figure 10 on page 77.

To configure the real servers, enter commands such as the following.

ServerIronADX(config)#server real R1 10.10.10.10ServerIronADX(config-rs-R1)#port httpServerIronADX(config-rs-R1)#exitServerIronADX(config)#server real R2 10.10.10.20ServerIronADX(config-rs-R2)#port httpServerIronADX(config-rs-R2)#exitServerIronADX(config)#server real R3 10.10.10.30ServerIronADX(config-rs-R3)#backupServerIronADX(config-rs-R3)#port httpServerIronADX(config-rs-R3)#exitServerIronADX(config)#server remote-name R4 10.10.10.40ServerIronADX(config-rs-R4)#port httpServerIronADX(config-rs-R4)#exitServerIronADX(config)#server remote-name R5 10.10.10.50ServerIronADX(config-rs-R5)#backupServerIronADX(config-rs-R5)#port http

Notice that the backup command is used with servers R3 and R5.

To configure the VIP, enter commands such as the following.

ServerIronADX(config-rs-R5)#server virtual-name-or-ip VIP1 10.10.10.100ServerIronADX(config-vs-VIP1)#port http lb-pri-serversServerIronADX(config-vs-VIP1)#bind http R1 http R2 http R3 http R4 http R5 http

ServerIronADX(config-vs-VIP1)# show server backup-associated-state Backup state info: *indicates the current selection Virtual server: vip1 Status: enabled IP: 10.1.1.100http:Primary: rs1: http(Active)* Backup: rs2: http(Active)



Designating a real server port as a backupBackup functionality can be configured at the application port level, meaning that for a given real server, you can specify one port to be a backup and another port as a primary. Figure 11 illustrates this feature.

FIGURE 11 Real server application ports configured as primaries and backups

In this example, real servers RS1 and RS2 are bound to a VIP. Each real server has three ports defined: HTTP, FTP, and DNS. RS1 is the primary server for HTTP and FTP, and the backup for DNS. RS2 is the primary server for DNS and the backup for HTTP and FTP. An HTTP or FTP request will not be sent to RS2 unless the HTTP or FTP service on RS1 is down, and a DNS request will not be sent to RS1 unless the DNS service on RS2 is down.

To configure the VIP and the real servers in Figure 11, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip vs1 10.10.10.10ServerIronADX(config-vs-vs1)#port httpServerIronADX(config-vs-vs1)#bind http rs1 http rs2 httpServerIronADX(config-vs-vs1)#port http lb-primary-serversServerIronADX(config-vs-vs1)#port ftpServerIronADX(config-vs-vs1)#bind ftp rs1 ftp rs2 ftpServerIronADX(config-vs-vs1)#port ftp lb-primary-serversServerIronADX(config-vs-vs1)#port dnsServerIronADX(config-vs-vs1)#bind dns rs1 dns rs2 dnsServerIronADX(config-vs-vs1)#port dns lb-primary-serversServerIronADX(config)#server real rs1 10.10.10.1ServerIronADX(config-rs-rs1)#port http ServerIronADX(config-rs-rs1)#port ftpServerIronADX(config-rs-rs1)#port dns backupServerIronADX(config-rs-rs1)#exitServerIronADX(config)#server real rs2 10.10.10.2ServerIronADX(config-rs-rs2)#port http backup ServerIronADX(config-rs-rs2)#port ftp backupServerIronADX(config-rs-rs2)#port dnsServerIronADX(config-rs-rs2)#exit

Syntax: [no] port port-name backup



Per server based real server backup

Overview of per server based real server backup

The current implementation of the backup server requires that all non-backup servers fail before SLB directs requests to backup servers. This method might not allow for maintaining the same level of performance in the server farm. The ability to maintain the same performance level for a given service is critical for many customers.

Per server based real server backup allows the backup servers to be associated with the specified primary servers. When a primary server fails, its backup server starts processing the traffic no matter what state the other primary servers are in. This feature works with the current real server backup mechanism by providing additional control of the backup server selection.

Current backup scheme

Currently, when a primary server goes down another server is selected among the active primary servers. Until all the primary servers are down, the server is selected from the backup servers. Additionally, you can configure the backup-stay-active option to keep the server selection in the backup groups active, even when some primary servers come back up.

Per server based backup scheme

With this feature, the associated primary and backup servers back up each other, regardless of the state of the other service ports. If a backup server is associated with a primary server, they work as a pair so that each can substitute for the other when it becomes unavailable.

If the backup-stay-active option is configured, the backup server continues to process the traffic even after the primary server comes up again.

Example

Primary servers: A and BBackup servers: C and DBackup association: C is backup of A, D is backup of B.

Condition 1: When A goes down and B is alive, the server is selected from C and B.

Condition 2: When both A and B go down, the server is selected from C and D.

Condition 3: if the backup-stay-alive option is not configured. When B comes up and A stays down alive, the server is selected from C and B.

Condition 4: if the backup-stay-alive option is configured, when B comes up and A stays down, the server is selected from C and D.

Slow start of the backup and the primary servers

If the server selection predictor is least connection, the backup server can be overwhelmed by the flood of the new connections when its primary server goes down. The same is true when the primary server goes back up and starts to take over the connections from the backup server. The slow start mechanism will be used whenever the switching of the backup or primary server happens, to give the server the chance to ramp up.



The slow start mechanism of the backup or the primary server will be the same as the one currently being used for the new servers. The slow start parameters are configured on the real server port.

NOTEThe slow start is enabled by default.

One backup per primary port or server

There will be the following restrictions:

• At the real port mode, the primary and backup ports have a one-to-one relationship. That is, the primary port can only be backed up by one backup port, and the backup port can only back up one primary port.

• At the real server mode, the primary and backup servers have a one-to-one relationship. That is, the primary server can only be backed up by one backup server, and the backup server can only back up one primary server.

The back port has the precedence over the back server

When both the port and the server backup are configured, the port configuration takes precedence over the server configuration.

For instance, the following is configured:

• The server C is the backup of the server A.

• The port 8080 of the server C is the backup of the port 8080 of the server B.

Then, the port 8080 of the server C becomes the backup of the port 8080 of the server B, but not the backup of the port 8080 of the server A.

Real server backup commands

• “Server backup association” on page 82

• “Server port backup association” on page 83

• “Display the backup bindings” on page 84

Server backup association

This command is to configure the backup server for a particular primary server, in the real server mode.

Syntax: [no] backup server-name

Example

To configure the real server R2 as the backup of the real server R1.

ServerIronADX(config)#server real-name R1 10.10.10.10ServerIronADX(config-rs-R1)#port httpServerIronADX(config-rs-R1)#exitServerIronADX(config)#server real-name R2 10.10.10.20ServerIronADX(config-rs-R2)#backup R1ServerIronADX(config-rs-R2)#port httpServerIronADX(config-rs-R2)#exit



Server port backup association

This command is to configure the backup server port for a particular primary server port, in the real server port mode.

Syntax: [no] port port-name backup server-name port-name

Example

To configure the HTTP port of the real server R2 as the backup of the HTTP port of the real server R1.

ServerIronADX(config)#server real-name R1 10.10.10.10ServerIronADX(config-rs-R1)#port httpServerIronADX(config-rs-R1)#exitServerIronADX(config)#server real-name R2 10.10.10.20ServerIronADX(config-rs-R2)#port httpServerIronADX(config-rs-R2)#port http backup R1 httpServerIronADX(config-rs-R2)#exit

NOTEWhen both server backup and server port backup are configured, the server port backup has the precedence over the server backup.

Example

ServerIronADX(config)#server real-name R1 10.10.10.10ServerIronADX(config-rs-R1)#port httpServerIronADX(config-rs-R1)#exitServerIronADX(config)#server real-name R2 10.10.10.20ServerIronADX(config-rs-R2)#port httpServerIronADX(config-rs-R2)#port http R1 httpServerIronADX(config-rs-R2)#exitServerIronADX(config)#server real-name R3 10.10.10.30ServerIronADX(config-rs-R2)#backup R2ServerIronADX(config-rs-R2)#port httpServerIronADX(config-rs-R2)#port http backup R1 httpServerIronADX(config-rs-R2)#exit

The server R3 will be the backup of R2, while the HTTP port on R3 will be the backup of the HTTP port on R1.


Configuring Direct Server Return2

Display the backup bindings

This command is used to display the binding relationship between the servers and the ports.

Syntax: show server backup-server-port-binding

Example

Configuring Direct Server Return In some ServerIron ADX implementations both client-to-server and server-to-client traffic flow through ServerIron ADX. In such configurations, the ServerIron ADX uses two sessions for each connection: one session for the client-to-server traffic and a second session is for the server-to-client traffic.

Direct Server Return (DSR) configurations enhance server response times and increase capacity on the ServerIron ADX by allowing server responses (server-to-client traffic) to bypass the ServerIron ADX.

Direct Server Return may be used in many different ServerIron ADX implementations. For example, it can be used on a single ServerIron ADX supporting a single server farm or applied to multiple ServerIron ADXs in high availability (HA) scenarios (Hot Standby HA, Symmetric Active-Standby HA, and Symmetric Active-Active HA).

FIGURE 12 Two ServerIron ADXs in an DSR configuration

ServerIronADX(config)#server real-name R1 10.10.10.10ServerIronADX(config-rs-R1)#port httpServerIronADX(config-rs-R1)#exitServerIronADX(config)#server real-name R2 10.10.10.20ServerIronADX(config-rs-R2)#backup R1ServerIronADX(config-rs-R2)#port httpServerIronADX(config-rs-R2)#port http backup R1 httpServerIronADX(config-rs-R2)#exitServerIronADX(config)#show server backup-server-port-bindingServer/Port State - 0: disabled, 1:enabled, 2:failed, 3:test, 4:suspect, 5:grace_dn, 6:active Real Server rs3:(state 6) Backup Server : rs2(state 6) Port 80(state 6) <---------- Port rs2:80(state 6)


Configuring Direct Server Return 2

ServerIron ADX supports both Layer 2 Direct Server Return (L2 DSR) and Layer 3 Direct Server Return (L3 DSR). The steps required to configure support L2 DSR and L3 DSR differ significantly.

• In an L2 DSR configuration, the ServerIron ADX and the real servers must be on the same subnet.

• In an L3 DSR configuration, the ServerIron ADX and the real servers can be connected by a router.

NOTEThe ServerIron ADX does not support Boolean health checks with DSR.

Configuring L2 Direct Server ReturnA ServerIron ADX configured for L2 DSR acts as a dispatcher, sending client requests for a VIP directly to the real server, which responds directly to the client. The ServerIron ADX does not translate the destination IP address in the client’s request from the VIP into the real server’s IP address as in other SLB configurations. Instead, the ServerIron ADX leaves the destination IP address unchanged.

NOTEIn an L2 DSR configuration, you cannot router hop between the ServerIron ADXs. They must have Layer 2 connectivity.

Two changes must be implemented to support L2 DSR:

• Support for L2 DSR must be enabled on individual TCP/UDP ports when you configure the virtual server (DSR VIP).

• A loopback address must be configured on each real server and the appropriate VIP address must be assigned to that loopback interface.

Enabling L2 DSR on TCP/UDP ports

To configure the ServerIron ADX for L2 DSR, you must enable the feature for individual TCP/UDP ports when configuring the virtual server.

For example, when you enable TCP port 80 (HTTP) on a virtual server, you can add the DSR parameter to enable L2 DSR for that port.

ServerIronADX(config)#server virtual-name-or-ip v1 10.157.22.1ServerIronADX(config-vs-v1)#port 80 dsr

Traffic for other ports still returns through the ServerIron ADX. The ServerIron ADX does not translate the destination IP address in client requests for the port with L2 DSR enabled. However, the ServerIron ADX still translates the destination IP address in the client’s request to the real server’s IP address for other ports.

Syntax: [no] port tcp/udp-port dsr

NOTEFor an IPv4 VIP, if there is already an IPv6 server bound, trying to configure the port to be dsr will not be allowed by the ServerIron ADX CLI.



Configuring the loopback address on a real server

To configure the real servers for L2 DSR, configure a loopback interface on each real server and assign the VIP addresses to the loopback interface.

The loopback interface enables the real server to respond to client requests directed at the VIPs, while at the same time keeping the real server “hidden”. The loopback interface responds to unicast traffic directed to it, but does not respond to ARP requests. The ServerIron ADX responds to pings and ARPs for the VIPs. Thus, any attempt to obtain the real server’s MAC address using ARP protocol does not succeed.

You can configure loopback addresses on some common types of real servers. Refer to the “Server-specific Loopback Configurations” on page 457 for details.

Health checks with L2 DSR

Normally, the ServerIron ADX can perform health checks on an application port only when a server replies from that port pass back through the ServerIron ADX. If the ServerIron ADX does not see the real server’s responses to client requests, the ServerIron ADX concludes that the application or the entire server is down and stops sending client requests to that server.

When you enable an application port for DSR, the ServerIron ADX can still perform heath checks on the application by sending the health checks to the loopback address you configure on the real server.

You can use Layer 4 and Layer 7 health checks in your DSR configuration.

• The ServerIron ADX addresses Layer 3 (IP ping) health checks to the real server IP address.

• The ServerIron ADX addresses Layer 4 and Layer 7 health checks to the real server MAC address and to the loopback address that matches the VIP address.

The configuration procedures for the health checks are the same as for other types of SLB. Refer to Chapter 4, “Health Checks”.

SYN-Defense with L2 DSR

SYN-Defense is a security feature that configures the ServerIron ADX to complete the TCP three-way handshake on behalf of a connecting client.

ServerIron ADX releases that do not support Layer 3 do not support the SYN-Defense feature in Direct Server Return configurations. The reason is that the ServerIron ADX does not see the server’s SYN ACK, and as a result cannot complete the connection. The incomplete connection resides on the server as a pending connection, a condition the SYN-Defense feature is meant to eliminate.

TrafficWorks router software enables you to use the SYN-Defense feature in a Direct Server Return configuration. To do so, configure the server to use the ServerIron ADX as its default gateway.

Placing a session in delete queue

DSR fast delete places a session in a delete queue upon seeing the first FIN in Direct Server Return (as opposed to the standard two FINs). The session is deleted in eight seconds instead of the standard two minute FIN session age.



The DSR fast-delete option is enabled by default, starting with 12.4.00 software release. To disable the option, enter commands as follows:

ServerIronADX(config)#server virtual-name-or-ip vsServerIronADX(config-vs-vs)#port 80 dsr no-fast-delete

Syntax: [no] port port dsr no-fast-delete

NOTEThe default setting is recommended in most cases because in DSR setup ServerIron ADX will not be able to see a FIN message from a server, resulting into session piling up and connection drops when the same TCP connection is reused within two minutes by a client.

L2 DSR configuration example

Direct Server Return may be used in many different ServerIron ADX implementations including high availability (HA) scenarios (Hot Standby HA, Symmetric Active-Standby HA, and Symmetric Active-Active HA). Figure 13 shows an example of an L2 DSR configuration for a high availability scenario.

FIGURE 13 ServerIron ADXs deployed in Direct Server Return configuration

To implement the configuration shown in Figure 13, configure ServerIron ADXs A and B. Because multiple VIPs are mapped to the same ports on the same real servers, TCP/UDP port binding is used. Thus, port 180 on VIP2 on ServerIron ADX A and on VIP1 on ServerIron ADX B is a logical port that is bound to port 80 on the real servers. For more information, refer to “Multiple port binding” on page 98.



Note the dsr parameter on the port commands that add the HTTP port (TCP port 80) to the VIPs. To enable L2 DSR for additional TCP/UDP ports, use the dsr parameter for each port when you add the port to a VIP.

NOTEBe sure you configure all the real servers on both ServerIron ADXs, and bind the VIPs on each ServerIron ADX to all the real servers.

NOTEBrocade recommends that you specify 2 (instead of 1) as a low priority or 254 (instead of 255) as a high priority. This way, you can easily force failover of the high priority ServerIron ADX to the low priority ServerIron ADX by changing the priority on just one of the ServerIron ADXs. For example, you can force a failover by changing the priority on the high priority ServerIron ADX from 254 to 1. Since the priority on the low priority ServerIron ADX is 2, the low priority ServerIron ADX takes over for the VIP. Likewise, you can force the low priority ServerIron ADX to take over by changing its priority to 255, since the priority on the high priority ServerIron ADX is only 254.

Configuring ServerIron ADX ANotice that all four real servers must be configured, and bound to the VIPs, on both ServerIron ADXs. Notice also that two HTTP ports are added to each real server. This type of configuration requires that you use the TCP/UDP port binding feature to bind the ports on the two real servers to the same port on the virtual server. For information, refer to “Multiple port binding” on page 98.

To configure the real servers, enter the following commands.

ServerIronADXA(config)#server real-name Real_Server_1 10.0.0.1ServerIronADXA(config-rs-Real_Server_1)#port httpServerIronADXA(config-rs-Real_Server_1)#port 80ServerIronADXA(config-rs-Real_Server_1)#exitServerIronADXA(config)#server real-name Real_Server_2 10.0.0.2ServerIronADXA(config-rs-Real_Server_2)#port http

TABLE 4 DSR configuration example

ServerIron ADX

Domain name Virtual IP (VIP) address

Priority VIP’s TCP port

Real IP address

Real Server’s TCP port

A www.abc.com VIP1:10.157.22.100

254 80 Real Server 1: 10.0.0.1

80

Real Server 2: 10.0.0.2

80

A www.def.com VIP2:10.157.22.101

2 80 Real Server 1: 10.0.1.1

180


180

B www.abc.com VIP1:10.157.22.100

2 80 Real Server 3: 10.0.0.1

180


180

B www.def.com VIP2:10.157.22.101

254 80 Real Server 3: 10.0.1.1

80


80



ServerIronADXA(config-rs-Real_Server_2)#port 80ServerIronADXA(config-rs-Real_Server_2)#exitServerIronADXA(config)#server real-name Real_Server_3 10.0.1.1ServerIronADXA(config-rs-Real_Server_3)#port httpServerIronADXA(config-rs-Real_Server_3)#port 180ServerIronADXA(config-rs-Real_Server_3)#exitServerIronADXA(config)#server real-name Real_Server_4 10.0.1.2ServerIronADXA(config-rs-Real_Server_4)#port httpServerIronADXA(config-rs-Real_Server_4)#port 180ServerIronADXA(config-rs-Real_Server_4)#exit

To configure the VIPs, enter the following commands.

ServerIronADXA(config)#server virtual-name-or-ip VIP1 10.157.22.100ServerIronADXA(config-vs-VIP1)#port http dsrServerIronADXA(config-vs-VIP1)#bind http Real_Server_1 http Real_Server_2 http Real_Server_3 http Real_Server_4 httpServerIronADXA(config-vs-VIP1)#sym-priority 254ServerIronADXA(config-vs-VIP1)#exitServerIronADXA(config)#server virtual-name-or-ip VIP2 10.157.22.101ServerIronADXA(config-vs-VIP2)#port http dsrServerIronADXA(config-vs-VIP2)#bind http Real_Server_1 80 Real_Server_2 80 Real_Server_3 180 Real_Server_4 180ServerIronADXA(config-vs-VIP2)#no http port translateServerIronADXA(config-vs-VIP2)#sym-priority 2ServerIronADXA(config-vs-VIP2)#exitServerIronADXA(config)#write memory

Configuring ServerIron ADX BTo configure the real servers, enter the following commands.

ServerIronADXB(config)#server real-name Real_Server_1 10.0.0.1ServerIronADXB(config-rs-Real_Server_1)#port httpServerIronADXB(config-rs-Real_Server_1)#port 180ServerIronADXB(config-rs-Real_Server_1)#exitServerIronADXB(config)#server real-name Real_Server_2 10.0.0.2ServerIronADXB(config-rs-Real_Server_2)#port httpServerIronADXB(config-rs-Real_Server_2)#port 180ServerIronADXB(config-rs-Real_Server_2)#exitServerIronADXB(config)#server real-name Real_Server_3 10.0.1.1ServerIronADXB(config-rs-Real_Server_3)#port httpServerIronADXB(config-rs-Real_Server_3)#port 80ServerIronADXB(config-rs-Real_Server_3)#exitServerIronADXB(config)#server real-name Real_Server_4 10.0.1.2ServerIronADXB(config-rs-Real_Server_4)#port httpServerIronADXB(config-rs-Real_Server_4)#port 80ServerIronADXB(config-rs-Real_Server_4)#exit

To configure the VIPs, enter the following commands.

ServerIronADXB(config)#server virtual-name-or-ip VIP1 10.157.22.100ServerIronADXB(config-vs-VIP1)#port http dsrServerIronADXB(config-vs-VIP1)#bind http Real_Server_1 180 Real_Server_2 180 Real_Server_3 80 Real_Server_4 80ServerIronADXB(config-vs-VIP1)#no http port translateServerIronADXB(config-vs-VIP1)#sym-priority 2ServerIronADXB(config-vs-VIP1)#exitServerIronADXB(config)#server virtual-name-or-ip VIP2 10.157.22.101ServerIronADXB(config-vs-VIP2)#port http dsrServerIronADXB(config-vs-VIP2)#bind http Real_Server_1 http Real_Server_2 http



Real_Server_3 http Real_Server_4 httpServerIronADXB(config-vs-VIP2)#sym-priority 254ServerIronADXB(config-vs-VIP2)#exitServerIronADXB(config)#write memory

Configuring L3 Direct Server ReturnIn an L3 DSR configuration, the ServerIron ADX marks all packets sent to servers bound to a specified VIP (the L3 DSR VIP) by setting the DSCP field to a configured value.

The real server must be programmed to check the DSCP field of incoming packets and change the source IP address of appropriate reply packets from its own IP address (real IP address) to the virtual IP address (VIP).

Three changes must be implemented to support L3 DSR:

• TOS marking of SLB and health check packets: All SLB and health check traffic sent to servers bound to a specified VIP must be marked by a specific DSCP field value. Use the tos-marking command to specify the DSCP field value.

• Special intelligence on real servers: The real server must be programmed to check the DSCP field of incoming packets and change the source IP address of appropriate reply packets from its own IP address (real IP address) to the virtual IP address (VIP).

• Special intelligence for handling health check responses: To enable the ServerIron ADX to correctly handle health check replies you must configure hc-l3-dsr under the VIP using the tos-marking command with the hc-l3-dsr option.

TOS marking of SLB and health check packets

To configure the ServerIron ADX for L3 DSR, the ServerIron ADX must set the DSCP field value in all packets sent to servers bound to a specified VIP.

Use the tos-marking command within a VIP configuration to specify the DSCP field value of traffic packets send to real servers bound to a specific VIP.

ServerIronADX(config)#server virtual-name-or-ip vip1 10.10.1.151ServerIronADX(config-vs-vip1)#tos-marking 18ServerIronADX(config-vs-vip1)#bind http rs1 httpThe ServerIron ADX sets the DSCP field value to 18 in all packets sent to real server rs1.

Use the hc-l3-dsr option to ensure that ServerIron ADX will process the health check reply packets correctly:

ServerIronADX(config)#server virtual-name-or-ip vip1 10.10.1.151ServerIronADX(config-vs-vip1)#tos-marking 18 hc-l3-dsrServerIronADX(config-vs-vip1)#bind http rs1 httpAlthough the ServerIron ADX will have sent health check probes to the real server IP, it will receive replies from the VIP. The hc-l3-dsr option ensures that responses from a different IP address are handled correctly.

Syntax: tos-marking DSCP-value [ hc-l3-dsr ]

The DSCP-value variable specifies the value of the DSCP field that you want to send to all packets sent to servers bound to the VIP.

With the hc-l3-dsr option configured the health check reply packets will be sent back to the VIP on the ServerIron ADX.



Special handling by real servers

L3 DSR requires special intelligence on the real server. Real servers must be programmed to check for DSCP field values in incoming packets and, if the received DSCP value matched a preconfigured value, change the source IP address of reply packets from its own IP address (real-ip) to a virtual IP address (virtual-ip).

Health checks with L3 DSR

When TOS marking is configured, all health check packets to TCP and UDP real server ports bound under a VIP, will have DSCP field set with a configured value. If special handling is enabled on the real servers, reply packets will come from VIP instead of the real server IP. For the ServerIron ADX to process these reply packets correctly, you must configure tos marking using the hc-l3-dsr option.

With the hc-l3-dsr option configured the health check reply packets will be sent back to the VIP on the ServerIron ADX. If you have the tos-marking command configured without this option, if a reply packet has the VIP as its source IP address, health checks will fail and the packet will be dropped.

The tos-marking hc-l3-dsr command implicitly enables DSR fast-delete. Hence, the option expedites deleting DSR SLB sessions when ADX receives a first TCP FIN message from a client; this behavior is similar to dsr fast-delete for L2 DSR. For information, refer to “Placing a session in delete queue” on page 86.

NOTEFor ICMP health checks, the ServerIron ADX does not mark the DSCP field.

L3 DSR configuration example

To enable Layer 3 DSR, you must configure a ServerIron ADX to set the DSCP field to a configured value in all packets sent to servers bound to a specified VIP (L3 DSR VIP).

Use the tos-marking command with the hc-l3-dsr option under the VIP to set the DSCP field to a configured value. The hc-l3-dsr option makes the ServerIron ADX to accept health check packets coming from the L3 DSR VIP rather than the real server IP address.

To enable Layer 3 DSR, perform the following steps.

1. Configure a real server as a remote server because it is not connected to any VLANs on the ServerIron ADX.

ServerIronADX(config)#server remote-server rs1 10.20.1.31ServerIronADX(config-rs-rs1)#port httpServerIronADX(config-rs-rs1)#exit

2. Define an SLB VIP and make it to an L3 DSR VIP by configuring the tos-marking command and hc-l3-dsr option.

ServerIronADX(config)#server virtual-name-or-ip vip1 10.1.1.151ServerIronADX(config-vs-vip1)#tos-marking 20 hc-l3-dsr

In this example, ServerIron ADX sets the DSCP value to 20 in all packets, either for health check or server load balancing, sent to real server rs1. Note that ADX is not configured with source-nat even though you have a remote server.


Displaying server information2

NOTETo make the above configuration work, the real server must have a special intelligence. When the server receives a packet with DSCP value 20, it should use "10.1.1.151" as a source IP address in response packets.

NOTEWhen DSR is configured, the server directly responds to the client, therefore, if the user binds different real server ports and virtual server ports, e.g. port 8080 of real server to port 80 of virtual server, the DSR traffic will not work.

Displaying server informationThe show server command, as a standalone command, gives the output of the following commands together:

• show server global - Refer to “Displaying global Layer 4 ServerIron ADX configuration” on page 505.

• show server bind - Refer to “Displaying port-binding information” on page 519.

• show server sessions - Refer to “Displaying port-binding information” on page 519.

• show server traffic - Refer to “Displaying packet traffic statistics” on page 522.

The show server global command gives the output of the show server backup or the show server symmetric command, depending on which high availability method is in use, plus some additional configuration information that would have to be shared between a pair of ServerIron ADXs in a high availability environment.

The following is a sample for a ServerIron using Symmetric Active-Active HA.

ServerIronADX#show server Server Symmetric port = 2/7 Group_id = 1 Candidate cnt = 1 Port No-rx 2/7 0Server Load Balancing - global parameters Predictor = round-robin Force-deletion = 0 Reassign-threshold = 20 Reassign-limit = 3 TCP-age = 30 UDP-age = 5 Sticky-age = 5 TCP-syn-limit = 65535 msl = 8 TCP-total conn = 0 Unsuccessful conn = 0 NO-RESET-on-max-conn = Disabled Ping-interval = 2 Ping-retries = 4 Session ID age = 30


Displaying server information 2

Bind infoVirtual server: v Status: enabled IP: 192.168.199.99 telnet -------> a: 192.168.99.11, telnet (remote) (Active) b: 192.168.99.12, telnet (remote) (Failed) http -------> a: 192.168.99.11, http (remote) (Active) b: 192.168.99.12, http (remote) (Failed)Client->Server = 0 Server->Client = 0Drops = 0 Aged = 0Fw_drops = 0 Rev_drops = 0FIN_or_RST = 0 old-conn = 0Disable_drop = 0 Exceed_drop = 0Stale_drop = 0 Unsuccessful = 0SYN def/proxy RST = 0 Server Resets = 0Out of Memory = 0 Out of Memory = 0last conn rate = 0 max conn rate = 0last TCP attack rate = 0 max TCP attack rate = 0fast vport found = 4 fast vport n found = 11Fwd to non-static FI = 0 Dup stale SYN = 0

ServerIronADX#show server Server Symmetric port = 2/7 Group_id = 1 Candidate cnt = 1 Port No-rx 2/7 0Server Load Balancing - global parameters Predictor = round-robin Force-deletion = 0 Reassign-threshold = 20 Reassign-limit = 3 TCP-age = 30 UDP-age = 5 Sticky-age = 5 TCP-syn-limit = 65535 msl = 8 TCP-total conn = 0 Unsuccessful conn = 0 NO-RESET-on-max-conn = Disabled Ping-interval = 2 Ping-retries = 4 Session ID age = 30 Bind infoVirtual server: v Status: enabled IP: 192.168.199.99 telnet -------> a: 192.168.99.11, telnet (remote) (Active) b: 192.168.99.12, telnet (remote) (Failed) http -------> a: 192.168.99.11, http (remote) (Active) b: 192.168.99.12, http (remote) (Failed)


Port ranges2

Port rangesPort ranges can be defined under real servers or virtual servers. Port ranges can be used with bind statement under VIP. Additionally, you can define port profiles for a port range and specify characteristics such as TCP or UDP, keepalive timers, retires for all ports inside port range.

NOTEPort-policy definition is not supported with port range. This is because all ports inside a port range must have the same characteristics, and these characteristics can be defined using port profile.

The ServerIron ADX processes client requests destined to ports inside a port range in the same way it processes connections to individual ports.

Client->Server = 0 Server->Client = 0Drops = 0 Aged = 0Fw_drops = 0 Rev_drops = 0FIN_or_RST = 0 old-conn = 0Disable_drop = 0 Exceed_drop = 0Stale_drop = 0 Unsuccessful = 0SYN def/proxy RST = 0 Server Resets = 0Out of Memory = 0 Out of Memory = 0last conn rate = 0 max conn rate = 0last TCP attack rate = 0 max TCP attack rate = 0fast vport found = 4 fast vport n found = 11Fwd to non-static FI = 0 Dup stale SYN = 0TCP forward FIN = 0 TCP reverse FIN = 0Fast path FWD FIN = 0 Fast path REV FIN = 0Fast path SLB SYN = 0 Dup SYN after FIN = 0Duplicate SYN = 0 Duplicate sessions = 0TCP ttl FIN recvd = 0 TCP ttl reset recvd = 0Sessions in DEL_Q = 0 Sess force deleted = 0Fwd sess not found = 0 sess already in delQ = 0Sess rmvd from delQ = 0New sess sync sent = 0 New sess sync recvd = 0TCP SYN received = 0 TCP SYN dropped = 0TCP SYN to MP = 0 TCP SYN ACK to MP = 0TCP SYN ACK received = 0 TCP SYN ACK dropped = 0TCP pkt received = 0 TCP pkt dropped = 0TCP pkt to MP = 0 PBSLB tftp status = Not in proAvail. Sessions on MP = 999993 Total Sessions on MP = 1000000slot-1 cpu-1 Avail. Session = 1999992 Total Sessions = 2000000slot-1 cpu-2 Avail. Session = 1999992 Total Sessions = 2000000slot-1 cpu-3 Avail. Session = 1999992 Total Sessions = 2000000Total C->S Conn = 0 Total S->C Conn = 0Total Reassign = 0 Unsuccessful Conn = 0Server State - 0: disabled, 1:enabled, 2:failed, 3:test, 4:suspect,5:grace_dn, 6:activeReal Server State CurrConn TotConn TotRevConn CurrSessPeakConna 6 0 0 0 0 0b 1 0 0 0 0 0last conn rate = 0 max conn rate = 0last TCP attack rate = 0 max TCP attack rate = 0SYN def RST = 0 SYN flood = 0


Port ranges 2

Defining a port rangePort ranges are identified by their names. A port range can be created as follows.

1. Define the port range

ServerIronADX(config)#port-range pr1

Syntax: [no] port-range port-range-name

2. Identify the ports in the range.

ServerIronADX(config-pr-pr1)#port 8051 to 8100

Syntax: [no] port port-number to port-number

Enter the port’s numerical value for the port-number variable.

When defining a port range:

• Ports in a port range must be consecutive.

• You must define a starting port and an ending port for the range.

• The starting port must be greater than zero (0).

• The ending port must be larger than the starting port.

• There can be up to 50 ports in a port range.

• You can change the starting port and ending port using a single command. When changing the ports in a port range, if the port range is not used with a bind statement or other configuration, then the change is applied immediately; otherwise, the change remains pending until the apply port-range command is issued.

• You cannot include the default port (65535) and well-known ports in a port range.

• Furthermore, if role-based management is used, only the super user or global manager can create port ranges at the global configuration level. Role-based users can use port ranges and bind them under the real server and virtual server configuration levels. Also, role-based users can view the list of port ranges by issuing the show port-range command.

• If the system encounters an error while implementing port-range and its associated features, it will still go ahead and complete the process. It will then log an error message. The system user must manually remove the port-range config, correct the error, and re-apply the configuration until it succeeds.

• If you define many port ranges to cover many application ports (several hundreds or thousands of ports) then you need to keep an eye on MP CPU resources, because a system might not be able to handle health checks for all these ports. Disabling of health checks for several ports or port-ranges might be needed in such cases to prevent health check issues.

• Port ranges cannot be used with alias port ("real-port") definitions.

• Port ranges can be combined with Layer 4 switching only. They cannot be used with Layer 7 switching.

• Port ranges cannot be used with IPv6 services.

• Some of the other features not supported with port range are: PBSLB, TCS, boolean health check, scripted health check, track-groups, track-ports, tcp offload, and keepalive.


Port ranges2

Using a port range under a real server definitionYou can define port ranges under a real server definition.

ServerIronADX(config)#server real real1 10.0.0.1ServerIronADX(config-rs-real1)#port-range pr1


Enter the ID of the port range for the port-range-name variable. Refer to the rules in “Defining a port range” on page 95 for additional rules.

You can add more than one port range to a real server; however, the ports in the port ranges cannot overlap. For example, if you define PR1 to include ports 8051 to 8100 and define PR2 to include ports 8061 to 8110, then you cannot use these two port ranges under the same real server because ports are overlapping. Also, if a port is included inside a port range and that port range is specified under real server, then the port cannot be specified separately under same real server.

All commands available to a single application port are available to the ports in a port range. For example, you can configure keepalive for a port range as you would for a single port.

ServerIronADX(config)#server real rs1 10.0.0.1ServerIronADX(config-rs-rs1)#port-range pr1 keepalive

Using a port range under a virtual server definitionYou can define a port range under a virtual server.

ServerIronADX(config)#server virtual-name-or-ip virtual1 10.0.0.1ServerIronADX(config-vs-virtual1)#port-range pr1


Enter the ID of the port range for port-range-name.

The rules for including port ranges to a real server also apply to a virtual server. (Refer to “Using a port range under a real server definition”.)

Binding a port range for virtual ports to a real serverYou can bind a port range from under a virtual server to real servers. Binding a port range is equivalent to binding all ports contained in the port range to the specified real server. All rules that apply to single port bindings also apply to binding port ranges. In addition, you can bind different port ranges to a virtual server if the port ranges each have the same number of ports.

The binding is a one-to-one mapping, where the starting port in the virtual server port range is bound to the starting port in the real server port range. The second port in a virtual server port range is bound to the second port of a real server port range.

ServerIronADX(config)#port-range pr1ServerIronADX(config-pr-pr1)#port 8051 to 8100ServerIronADX(config-pr-pr1)#exitServerIronADX(config)#port-range pr2ServerIronADX(config-pr-pr2)#port 7051 to 7100ServerIronADX(config-pr-pr2)#exitServerIronADX(config)#server virtual-name-or-ip virtual1 10.0.0.1ServerIronADX(config-vs-virtual1)#bind-range pr1 realserver1 pr1 realserver2 pr2

Syntax: [no] bind-range port-range-name real-server-name port-range-name


Port ranges 2

Defining port profile for port rangeYou can define a profile for a port range. Policies and other features defined for a port profile are applied to all the ports included in the port range.

ServerIronADX(config)#server port-profile port-range pr1ServerIronADX(config-port-profile-range-pr1))#tcp keepalive use-master-state

Syntax: [no] server port-profile port-range port-range-name

The following commands are available under the port-profile-range configuration level:

• bringup-retries

• disable

• l4-bringup-interval

• l7-bringup-interval

• no-fast-bringup

• tcp

• udp

When defining a port profile for a port range, note the following:

• A separate port profile for an individual port inside a port-range definition is not permitted. All ports inside a port-range must have the same properties.

• In the case of overlapping port ranges that are used under different real servers, a port profile for only one of the port ranges is allowed. You cannot have conflicting properties for the same port under different port ranges.

Displaying a list of port rangesYou can display a list of port ranges that have been created in the ServerIron ADX by issuing the following command.

ServerIronADX(config)#show port-range

Syntax: show port-range [start-index]

Issuing the show port-range command displays information for all the port ranges configured on the ServerIron ADX. To limit the number of port ranges included in the output, issue the show port-range start-index command. Information only for the port ranges starting from the specified start-index is displayed.

ServerIronADX#show port-range Name Start End Pending Start Pending End RefCnt pr2 8090 8139 500 pr3 8140 8149 100 pr98 9800 9803 4 range4 7001 7050


Multiple port binding2

Using a start-index variable begins display at the record specified where the first record has a value of 0. In the following example, the start-index value of 2 is used on the same port-range displayed in the previous example.

To display a list of port ranges with a name that starts with a specified prefix, issue the following command.

ServerIronADX(config)#show port-range starts-with pr

Syntax: show port-range starts-with prefix

Table 5 describes the information in the output.

Multiple port bindingMultiple port binding allows you to bind one real server port to multiple virtual server ports.

ServerIron ADX supports two methods of associating a real server TCP or UDP port to multiple virtual TCP or UDP ports (VIPs): direct binding of multiple ports and port aliases.

• Direct binding of multiple ports enables to you to associate a real server TCP or UDP port directly to multiple virtual TCP or UDP ports. Using this method you do not need to configure additional alias ports for real ports or virtual ports in order to bind a single real server to multiple virtual servers; nor are alias ports needed to bind a real server to multiple virtual ports on a single virtual server.

• Port aliases bind a real server TCP or UDP port to multiple port aliases, which are bound to the virtual ports.

Although ServerIron ADX supports both direct binding of multiple ports and port aliases, the two methods cannot co-exist for the same real port or virtual port.

TABLE 5 Field descriptions of show port-range command

Field Description

Name Name of the port range

Start First port in the port range

End Last port in the port range

Pending Start The port range has been changed but the apply port-range command has not been issued. This column shows the start of the new port range.

Pending End The port range has been changed but the apply port-range command has not been issued. This column shows the end of the new port range.

RefCnt This field is used by developers for debugging purposes.

ServerIronADX(config)#show port-range 2Name Start End Pending Start Pending End RefCntpr98 9800 9803 4range4 7001 7050

ServerIronADX#show port-range starts with pr Name Start End Pending Start Pending End RefCnt pr2 8090 8139 500 pr3 8140 8149 100 pr98 9800 9803 4


Multiple port binding 2

To simplify an existing configuration that uses port aliases, you can manually convert that configuration to the direct binding method to reduce the size of SLB configurations. If you choose to use the direct method, you must first remove all alias port bindings and reload your configuration.

Direct binding of multiple portsDirect binding of multiple ports enables you to associate a real server TCP or UDP port with multiple virtual TCP or UDP ports.

Binding a real server port to multiple VIPs

To bind one real server port (rs1) to multiple VIPs (vs1 and vs2), complete the following steps:

1. Create a real server with one port.

ServerIronADX(config)#server real rs1 10.0.0.1ServerIronADX(config-rs-rs1)#port http

2. Create a virtual server.

ServerIronADX(config)#server virtual vs1 10.0.0.101

3. Create an HTTP port on the virtual server.

ServerIronADX(config-vs-vs1)#port http

4. Bind the real port on the real server to the HTTP port on the virtual server.

ServerIronADX(config-vs-vs1)#bind http rs1 http

5. Repeat the steps 2 through 4 for each additional virtual server.

ServerIronADX(config)#server virtual vs2 10.0.0.102ServerIronADX(config-vs-vs2)#port httpServerIronADX(config-vs-vs2)#bind http rs1 http.

Configuration rules

Although both direct binding of multiple ports and port binding of multiple ports via port aliases are supported by the ServerIron ADX, the two configurations cannot co-exist for the same real port or virtual port.

A real server port cannot be bound to a virtual port if any of the following conditions are met:

• The real port is already bound to another virtual port as an alias port.

• The virtual port has been bound to an alias port.

• The virtual port is configured for stateless or stateless fragmentation support. For more information, see “Fragmentation support in the stateless mode” on page 209.

• The virtual port is configured for persistent hashing. For more information, see “Enabling persistent hashing” on page 115.

When a real port is bound to multiple virtual ports, the following configurations are not allowed:

• A virtual port with a multiple port binding cannot be bound as an alias port.

• The real port cannot be bound as an alias port or use another port as an alias port.

• The virtual port cannot be configured for stateless or stateless fragmentation support.

• The virtual port cannot be configured for persistent hashing.



NOTEThe default port (a port the ServerIron ADX automatically configures on all real and virtual servers) and the source IP application port do not support multiple port binding.

Specifying the number of multiple port bindings available

Direct binding of multiple ports is enabled by default with the default value for the number of bindings allowed. Use the system-max l4-multi-binding command to change the number of multiple port bindings available or disable multiple port binding.

Syntax: system-max l4-multi-binding new_max

The new_max variable identifies the number of multiple port bindings that can be created. By default, you can create up to 32,000 multiple port bindings. A maximum of 300,000 multiple port bindings can be configured. If the new_max value is set to 0, support for multiple port binding is disabled.

Whenever you specify the number of multiple port bindings, you must restart the system if you change the new_max value to a different non-zero value. If reloading the system is not an option, you must remove all additional multiple port bindings before changing the new_max value.

The show server resource command displays the number of multiple port bindings.

The number of configured server ports and configured multiple port bindings can be captured by an SNMP trap when a certain threshold is reached.

In the output of the show server bind command, each additional binding is displayed with a + sign appended to it.

NOTEWhen you remove the primary binding in a multiple port binding configuration, the secondary binding continues to be displayed with the + sign but it does not effect any functionality. To remove the + sign from the secondary binding, remove and re-add the secondary binding. When you reboot the ServerIron ADX, the + sign disappears.

ServerIronADX1000#show server resourceServer resource usage: Current Maximuml4-real-server 2 1024l4-virtual-server 2 256l4-server-port 8 2048l4-multi-binding 1 32000

ServerIronADX1000#show server bindBind infoVirtual server: vs1 Status: enabled IP: 10.1.2.100 http -------> rs1: 10.1.2.1, http (Active) rs2: 10.1.2.2, http (Active)Virtual server: vs2 Status: enabled IP: 10.1.2.101 http -------> + rs1: 10.1.2.1, http (Active) + rs2: 10.1.2.2, http (Active)



Port aliasesWhen you associate a virtual port (VIP) with a real server, you make the association for a particular TCP or UDP port. The association of a TCP or UDP port on a VIP with a TCP or UDP port on a real server is called a "port binding".

In most configurations, only one VIP-to-real-server binding is made for a TCP or UDP port. For example, if you bind VIP 10.29.2.2 to real server 10.0.0.1 for port 80 (the well-known HTTP port), you do not generally create any other bindings between VIP 10.29.2.2 and real server 10.0.0.1 for the same port. However, should you wish to track statistics for multiple applications or domain names mapped to the same real server port, you can do so by creating multiple port bindings.

One method of binding a single real server port to multiple VIPs is to configure a port alias for each additional VIP. For example, if you want to associate three VIPs with the same real server, you can define two TCP or UDP port aliases, one for each of the additional VIPs.

In such a configuration, the ServerIron ADX collects and displays statistics and configuration information individually for each VIP, but sends all traffic to the same TCP or UDP port number on the real server.

Binding same real ports to multiple VIP ports

Multiple port binding enables a real server port to be bound to multiple VIP ports, which is useful when you want to bind multiple VIPs to a single application service on real servers, and the real servers are listening on different ports.

NOTEThis command is backward-compatible with the real-port command.

To bind multiple ports to one real server port, follow these steps.

1. Create a real server with two ports.

ServerIronADX(config)#server real rs1ServerIronADX(config-rs-rs1)#port 81ServerIronADX(config-rs-rs1)#port 8081 <- alias port

2. Create a second real server with two ports.

ServerIronADX(config)#server real rs2ServerIronADX(config-rs-rs2)#port 82ServerIronADX(config-rs-rs2)#port 8082 <- alias port

3. Create a virtual server.

ServerIronADX(config)#server virtual-name-or-ip vs1

4. Configure an HTTP port on the virtual server.

ServerIronADX(config-vs-vs1)#port http

5. Bind the alias ports to the real servers on the virtual servers.

ServerIronADX(config-vs-vs1)#bind http rs1 81 rs2 82

6. Create a second virtual server with an HTTP port.

ServerIronADX(config)#server virtual-name-or-ip vs2ServerIronADX(config-vs-vs2)#port http



7. Bind the alias ports to the real servers on the virtual servers.

ServerIronADX(config-vs-vs2)#bind http rs1 8081 real-port 81 rs2 8082 real-port 82

Syntax: bind virtual-port real-server-name alias-port [real-port real-port-num]

NOTEAlias ports should be treated like regular ports and should have the same server ID and group ID.

Binding a real server port to multiple VIPs

You can bind a real server port to multiple VIP ports with or without port translation. Port translation is useful in cases where different client groups require different VIPs.

The real-port option has been added to the existing port virtual subcommand.

Syntax: [no] port tcp/udp-port real-port real-server-port-to-use

NOTEThis feature takes precedence over the no port port translate virtual subcommand.

In the following examples, notice that alias port 8081 is defined for binding between the real server and virtual server. The alias port and the real-port option work together.

To bind one real server port to multiple VIPs (vs1 and vs2), enter commands such as the following.

To bind one real server port to multiple virtual ports of one VIP, enter commands such as the following.

server real rs port 8080 port 8081 <---- alias portserver virtual-name-or-ip vs1 port http bind http rs 8080server virtual-name-or-ip vs2 port http port http real-port 8080 <---- use real port 8080 to do port translation bind http rs 8081 <--- bind to alias port

server real rs port 8080 port 8081 <------ alias portserver virtual-name-or-ip vs port http bind http rs 8080 port 81 port 81 real-port 8080 <---- use real port 8080 to do port translation bind 81 rs 8081 <---- bind to alias port



Configuration rules

Use the following rules when configuring the ServerIron ADX to bind more than one virtual server to the same real server using the same application port:

• You must configure both the real port and the alias port on the real servers. For example, if you need to create alias port 180 so that you can bind two virtual servers to the same real server and application port (80) on a real server, you must configure port 80 and port 180 on the real server. Otherwise, you will not be able to completely bind all the virtual servers to the real server. In the example below, the following real server configurations are incomplete because neither of the real servers has both the untranslated and alias ports configured.

ServerIronADX(config)#server real-name r1 10.0.1.5 ServerIronADX(config-rs-r1)#port httpServerIronADX(config-rs-r1)#exitServerIronADX(config)#server real-name r2 10.0.2.200 ServerIronADX(config-rs-r2)#port 180ServerIronADX(config-rs-r2)#exit

• You cannot bind to both the untranslated port and the alias port in the same bind statement. In the example below, the following bind statement is invalid.

ServerIronADX(config-vs-VIP1)#port httpServerIronADX(config-vs-VIP1)#bind http r1 http r2 180

Here is a more detailed explanation.

When you configure SLB, one of the tasks you perform is to bind the TCP or UDP application ports on the virtual server to their counterparts on the real server. For example, if clients will be sending requests to port 80 (HTTP) on virtual server www.example8.com, but your real servers expect the HTTP connections to arrive on port 8080 of real server R1, you must bind port 80 on the virtual server to port 8080 on the real server.

One of the requirements is that a real server can be bound to only one virtual server using the same TCP or UDP application port. As a result, when you bind a real server port to a virtual server port, you cannot then bind the same real server port to a different virtual server port.

Normally, the ServerIron ADX translates the IP address and application port of the virtual server requested by the client into the real server IP address and application port that you bind to the virtual server. However, when you disable port translation, the ServerIron ADX does not perform the translation for the application port. Instead, the ServerIron ADX translates the destination IP address in the client’s request to the IP address of a real server, but leaves the application port in the client’s request untranslated.


To implement the configuration described above, enter commands such as the following.

ServerIronADX(config)#server real-name r1 10.0.1.5 ServerIronADX(config-rs-r1)#port httpServerIronADX(config-rs-r1)#port 180ServerIronADX(config-rs-r1)#exitServerIronADX(config)#server real-name r2 10.0.2.200 ServerIronADX(config-rs-r2)#port httpServerIronADX(config-rs-r2)#port 180ServerIronADX(config-rs-r2)#exitServerIronADX(config)#server virtual-name-or-ip VIP1 10.157.22.88ServerIronADX(config-vs-VIP1)#port httpServerIronADX(config-vs-VIP1)#bind http r1 http r2 http



ServerIronADX(config-vs-VIP1)#exitServerIronADX(config)#server virtual-name-or-ip VIP2 10.157.22.99ServerIronADX(config-vs-VIP2)#port httpServerIronADX(config-vs-VIP2)#no port http translateServerIronADX(config-vs-VIP2)#bind http r1 180 r2 180

The well-known port (80) is used for VIP1, but an alias (180) is used for VIP2. The real servers actually use port 80 for traffic to both virtual IP addresses. However, the alias port enables the ISP to distinguish among the two IP addresses and their traffic when they display SLB information on the ServerIron ADX. The no port http translate command is required. This command enables the ServerIron ADX to send traffic from multiple VIPs to the same real TCP/UDP port on the real server (in this example, “http” (port 80)). If you leave this command out, the ServerIron ADX does not use port 180 as an alias but instead sends the VIP traffic to TCP/UDP port 180 on the real server rather than 80.

NOTEBecause the untranslated port is logically bound to the translated port and both ports are bound to the same port on the real server, state information for the untranslated port is based on the translated port’s state. In this example, state information for port 180 is based on the state for port 80. The state is shown in the Ms (Master port state) field of the display produced by the show server real command. Refer to “Displaying real server information and statistics” on page 508.

To display statistics for the separate real IP addresses, enter the following command at any command prompt.

The lines highlighted in bold indicate the separate HTTP port numbers. The two HTTP lines for real server 1 (r1) indicate that an alias is in use. The first line lists the alias port number, and the second line lists the actual port number used by the real server. Even though the same port number is used on the real server, the ServerIron ADX display distinguishes the traffic for the two virtual IP addresses.

ServerIronADX(config)#show server realServer State - 1:enabled, 2:failed, 3:test, 4:suspect, 5:grace_dn, 6:activeName: r1 IP: 10.0.1.5 : 1 State: 3 Wt: 1 Max-conn: 1000000Src-nat (cfg:op) = 0: 0 Dest-nat-(cfg:op) = 0: 0

Port State Ms CurConn TotConns Rx-pkts Tx-pkts Rx-octet Tx-octet Reas180 enabled 2 0 0 0 0 0 0 0http enabled 0 0 0 0 0 0 0 0Keepalive: Disabled, status code(s) default (200-299, 401) HTTP URL: "HEAD /"defaulunbnd 0 0 0 0 0 0 0 0

Server Total 0 0 0 0 0 0 0

Name: r2 IP: 10.0.2.200 : 1 State: 3 Wt: 1 Max-conn: 1000000Src-nat (cfg:op) = 0: 0 Dest-nat-(cfg:op) = 0: 0

Port State Ms CurConn TotConns Rx-pkts Tx-pkts Rx-octet Tx-octet Reashttp enabled 2 0 0 0 0 0 0 0Keepalive: Disabled, status code(s) default (200-299, 401) HTTP URL: "HEAD /"defaulunbnd 0 0 0 0 0 0 0 0Server Total 0 0 0 0 0 0 0


Real server groups 2

NOTEThe state of the alias HTTP port is always the same as the state of the actual HTTP port used in the packets the ServerIron ADX sends to the real server. The state is shown in the Ms (Master port state) column in the show server real display. Refer to“Displaying real server information and statistics” on page 508.

Real server groupsA real server group is a container of multiple real servers that you can use to simplify and reduce the size of your load balancing configurations.

For large scale configurations you'll want to use real server groups to avoid reaching the 1.4MB configuration file size limit set by the ServerIron ADX.

Using real server groups you can reduce the size and complexity of load balancing configurations by associating multiple real servers with a single real server group and then binding that group to a virtual server. ServerIron ADX automatically binds all of the real servers associated with the real server group to the bound virtual server.

Real server group configuration is a three-step process:

• First, you must define the real server group.

• Once defined, you can associate one or more real servers with that real server group. Up to four real servers can be associated with a real server group in a single command.

• You can then bind the real server group to a virtual server.

Although a real server can be associated with one-and-only-one real server group, each real server group can be bound to multiple virtual servers.

Defining a real server groupTo define a real server group use the server group-real command.

ServerIronADX(config)#server group-real sg1

Syntax: [no] server group-real real-server-group-name

The real-server-group-name variable identifies the name of the real server group.

The no server group-real command enables you to delete a real server group. If you delete a real server group that has been bound to a virtual server, the ServerIron ADX automatically unbinds all of the real servers associated with that real server group. The real servers themselves are not deleted and remain intact in the configuration.

Associating a real server with a real server groupUse the real-server command to associate one or more real servers with a real server group.

Each real server can be associated with one-and-only-one real server group. If you associate a real server with a real server group that is already bound to a virtual server, ServerIron ADX automatically binds the newly associated real server to the virtual server.


Real server groups2

To associate up to four real servers with a real server group, enter a command such as the following:

ServerIronADX(config-rsg-sg1)#real-server rs1 rs2 rs3 rs4

Syntax: [no] real-server real-server-names

The exit-server-names variable specifies the real servers associated with a real server group.

The no real-server command enables you to disassociate a real server from a real server group. If you disassociate a real server from a real server group bound to a virtual server, ServerIron ADX automatically unbinds the real server. Only those real server bindings that were particular to the real server group are removed.

Binding a real server group to a virtual serverUse the bind group-real command to bind a real server group to a virtual server.

ServerIronADX 1000(config)#server virtual name-or-ip v1ServerIronADX 1000(config-vs-v1)#bind http group-real sg1 http

A real server group can be bound to multiple virtual servers.

Syntax: [no] bind virtual-server-port group-real real-server-group-name real-server-port

The virtual-server-port variable identifies the virtual server port to be bound to the real server group. The real-server-group-name variable specifies the name of the real server group to which the virtual server is bound. The real-server-port variable specifies the real server port.

NOTEDo not bind an empty real server group to a virtual server. You must associate at least one real server with a real server group before you bind that real server group with a virtual server otherwise ServerIron ADX issues an error.

Showing real server groupsUse the show server group-real command to view real server groups.

To view the real servers or virtual servers bound to a real server group, enter commands such as the following:

ServerIronADX(config)#show server group-real sg1Real server group: sg1rs2 rs3 rs4 rs5

Syntax: show server group-real real-server-group-name

The real-server-group-name variable identifies the name of the real server group.


Disabling or deleting VIPs and real ports 2

Disabling or deleting VIPs and real portsThis section provides information to disable or delete VIPs and real ports.

Disabling VIPsYou can globally or individually disable VIPs.

To globally disable all virtual servers, enter the following command.

ServerIronADX(config)#server disable-vip

Use the no server disable-vip command to globally re-enable virtual servers after disabling them.

Syntax: [no] server disable-vip

To disable an individual virtual server, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip www.foo.comServerIronADX(config-vs-www.foo.com)#disable

Use the no disable command to re-enable a virtual server.

Syntax: [no] disable

Disabling a real serverUnder the real server config level, you can disable a real server. Disabling a real server also disables all the existing real server ports. The real server state will become “disabled”, and no new connections will be assigned to a disabled real server. However, all the existing connections will remain. No health check will be done for a disabled real server.

To disable a real server, enter commands such as the following.

ServerIronADX(config)#server real rs1 10.1.1.1ServerIronADX(config-rs-rs1)#disable

Syntax: [no] disable

Disabling or re-enabling an application portApplication ports are enabled by default. To disable an application port on a virtual server, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip Zoot_Allures 10.2.3.4ServerIronADX(config-vs-Zoot_Allures)#port http disable

Syntax: [no] port tcp/udp-port disable

To re-enable a port, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip Zoot_Allures 10.2.3.4ServerIronADX(config-vs-Zoot_Allures)#no port http disable


Disabling or deleting VIPs and real ports2

Globally disabling real and virtual portsYou can globally disable a Layer 4 port on the ServerIron ADX. The port can be disabled for all real servers, all virtual servers or all real and virtual servers. After you disable a port globally, you can enable the port on individual real or virtual servers as necessary. By default, all real and virtual ports are enabled.

When the ServerIron ADX is booted, if the command to globally disable a real or virtual port exists in the startup-config file, the specified port is disabled at startup. When a real or virtual port is created, and the port has been disabled globally, the real or virtual port is disabled as well. You must enable the port explicitly.

To disable all real HTTP ports, enter commands such as the following.

ServerIronADX(config)#server port 80ServerIronADX(config-port-http)#disable realServerIronADX(config-port-http)#

To disable all virtual HTTP ports, enter commands such as the following.

ServerIronADX(config)#server port 80ServerIronADX(config-port-http)#disable virtualServerIronADX(config-port-http)#

To disable all real and virtual HTTP ports, enter commands such as the following.

ServerIronADX(config)#server port 80ServerIronADX(config-port-http)#disableServerIronADX(config-port-http)#

Syntax: disable [real | virtual]

Deleting a VIPIt is critical that you follow the steps below before deleting a VIP that is in production or is handling live traffic.

1. Disable the real server ports that are associated with this virtual server port.

Syntax: [no] server real real-server-name

Syntax: [no] port port disable

2. Keep checking the current connection count against the real server until the connection count falls to zero.

Syntax: show server real real-server-name

3. If the current connection value does not drop to zero after some time has passed, then unbind the real server port from under the VIP.

Syntax: no bind virtual-port real-server-name real-server-port

4. Double check to make sure that real server is unbound from the virtual server.

Syntax: show server bind

If the real server is not unbound properly, then check the connection count under the BP console and try clearing the server sessions.

ServerIronADX#rconsole 1 1ServerIronADX1/1#show server real rs1



ServerIronADX1/1#rconsole-exitServerIronADX#rconsole 1 2ServerIronADX1/2#show server real rs1ServerIronADX1/1#rconsole-exitServerIronADX#rconsole 1 3ServerIronADX1/3#show server real rs1ServerIronADX1/1#rconsole-exit

Syntax: rconsole slot# BP#

Syntax: show server real real-server-name

Syntax: rconsole-exit

If there are existing connections or the port is still in AWU or AWM state, then clear the server sessions using following command.

Syntax: clear server all-session real-server real-server-name port real-port

5. After the connection count drops to zero or the unbinding is successful, delete the VIP.

Syntax: no server virtual virtual-server-name

6. If real servers are not required, then delete those also.

Syntax: no server real real-server-name

If any current connection or current session cannot be disabled and the port is in "AWU" or "AWM", then issue a clear server all-session command.

Enabling force-deleteSLB and TCS allow the graceful shutdown of servers and services. By default, when a service is disabled or deleted, the ServerIron ADX does not send new connections to the real servers for that service. However, the ServerIron ADX does allow existing connections to complete normally, however long that takes.

You can force the existing SLB connections to be terminated within two minutes, by using the server force-delete command.

If you disable or delete a service, do not enter an additional command to reverse the command you used to disable or delete the service, while the server is in graceful shutdown.

NOTERefer to “Real server shutdown” on page 110 for important information about shutting down services or servers.

Suppose you have unbound the Telnet service on real server 15, but you do not want to wait until the service comes down naturally. You can force server load-balancing connections to be terminated by entering the following command.

ServerIronADX(config)#server force-delete

Syntax: server force-delete

To display active sessions for a specific server, enter show server real server number and a display as seen below will appear. Notice that the display below shows the Telnet connection on server 15 as awaiting unbinding. Without server force-delete, this feature will stay in this state until the session ends naturally.



Because the binding is awaiting deletion, it will also still be seen as an active binding, if you enter the show server bind command, such as the following.

After force delete is enabled, the unbinding will occur within two minutes.

NOTEThe binding for the real server will also be eliminated from the output of the show server bind command.

Real server shutdownThe force shutdown feature (sometimes called the force delete feature) allows you to force termination of existing SLB connections. This feature assumes that you already have shut down a TCP/UDP service on the real server, or you have shut down the real server itself.

There are several methods for shutting down a service or server. Each method has consequences, so choose the method that works best in your situation. The methods are as follows:

• Edit the real server configuration on the ServerIron ADX to disable the TCP/UDP ports on the server. For example, to disable port 80 (HTTP), you can use the port http disable command at the real server level of the CLI. If you use this method, you do not need to re-define the real server to add the server back to SLB. However, you do need to re-enable the disabled TCP/UDP ports.

• Delete the real server from the ServerIron ADX. This option immediately prevents new connections. To safely delete the real server from the ServerIron, we recommend the following procedure.

1. Under the real server, disable the application ports.

2. Check to ensure the current connections and session comes down to zero (in show server real output).

3. Under VIP, unbind the real server.

4. Delete the real server.

The ServerIron ADX allows existing connections to end normally or, if you have enabled the force shutdown option, the ServerIron ADX ends all connections within two minutes. If you use this method and later want to re-add the real server to the ServerIron ADX, you must redefine the real server, then rebind the real server to the appropriate VIP.

ServerIronADX(config-vs-building)#show server bindVirtual Server Name: building, IP: 10.95.5.130 http -------> s21: 10.95.18.21, http s15: 10.95.18.15, http s50: 10.95.18.50, http ftp -------> s50: 10.95.18.50, ftp s21: 10.95.18.21, ftp s15: 10.95.18.15, ftp telnet -------> s15: 10.95.18.15, telnet s21: 10.95.18.21, telnet s50: 10.95.18.50, telnet



• Shut down the real server itself, rather than change definitions on the ServerIron ADX. When the real server stops responding to health checks, the ServerIron ADX removes the server from the SLB. This option is simple because it does not require any configuration changes on the ServerIron ADX. However, this option immediately disconnects all users, whereas the above options allow the server or service to gracefully shut down (unless you use the force shutdown option).

Port holddown timerWhen a real server port is disabled, a ServerIron ADX stops sending any new connections to the port. Configuring the server force-delete command ensures that existing sessions are terminated within two minutes. If a real server port is disabled and enabled quickly before the force-delete operation has completed, stale sessions can potentially cause problems for clients seeking access to the real servers.

Enabling the port holddown timer disallows a failed port from being marked active until all idle sessions have timed out. Thus, when a real port is disabled and enabled quickly before a configurable timeout (default 2 minutes) has elapsed, the port is not allowed to move to the active state and is held in a special helddown state. This is a pseudo-state while the port transitions from active to failed and then to testing. If the subsequent health check is successful, the port is marked as active.

If all the ports bound to a VIP are in the helddown state, the VIP would still be in the inactive state. The behavior of VIP health does not change. Where VIP health is concerned, a real port in the helddown state is equivalent to a real port in the failed state.

Table 6 describes the behavior of the ServerIron ADX for a specified action when it is configured with the server force-delete command, with port hold-down timer, and in a normal scenario without either configured.

Behavior with flapping ports

If a port keeps flapping within the configured port holddown timeout period, the port is held down until the port stops flapping for the configured timeout. In practice this means that the port must be available for a time interval greater than the configured timeout period for it to come back up.

NOTEIf a port that was disabled when the holddown timer is started is enabled within the timeout period, the port is held down until the timeout period has passed.

TABLE 6 Behavior with server force-delete command

Action Normal Scenario With Force-Delete With Port Hold-down

Delete Real Server Sessions deleted within 2 minutes.

Sessions deleted within 2 minutes.

If real server is re-added, it is treated as a new server addition and port isn’t held down.

Unbind Port Sessions deleted within 2 minutes.


If re-bound, the port is not held down.

Disable Real Server Port

Existing sessions continue to exist through their lifetime.


If enabled quickly (within the timeout) the port is held down.

Real Port Fails Existing sessions continue to exist through their lifetime.

Existing sessions continue to exist through their lifetime.

If the port comes up quickly, the port is held down.



The port hold-down timer can be configured globally, per real server port and per port-profile.

Changing the default port holddown timer value

The default holddown timeout is 2 minutes. The following command allows you to configure this global timeout value or reset the timeout to the default.

ServerIronADX(config)#server port-holddown-timeout 240

Syntax: [no] server port-holddown-timeout timeout-value

The timeout-value variable specifies the length of the port holddown timer in seconds. Acceptable values are 1 second to 86400 seconds (1 day). The default value is 120 seconds (2 minutes).

The value set by this command applies to all port holddown configurations.

Enabling the port holddown timer globally

You can configure the port holddown timer globally to enable port hold down for all ports on all real servers. This setting overrides any configurations for individual ports.

ServerIronADX(config)#server port-holddown

Syntax: [no] server port-holddown

Enabling the port hold down timer for an individual real server port

You can configure the port hold down timer to enable port holddown for an individual port within a real server configuration.

ServerIronADX(config)#server real rs1ServerIronADX(config-real-rs1)#port http holddown

Syntax: [no] port port-type holddown

The port-type variable specifies the port that you want to apply the holddown timer to.

Enabling the port holddown timer for a port profile

You can configure the port hold down timer to enable port holddown for all ports within a server port profile.

ServerIronADX(config)#server port httpServerIronADX(config-port-http)#holddown

Syntax: [no] holddown



Displaying port holddown

The show server real and show server real detail commands provide information about the current state and duration of port holddown.

In the following example, the show server real command displays the state of the “http” port as “HLD”.

The time remaining for the holddown state is displayed by the show server real detail command as shown in the following.

ServerIronADX(config)#show server real rs1Real Servers Info========================State(St) - ACT:active, ENB:enabled, FAL:failed, TST:test, DIS:disabled, UNK:unknown, UNB:unbind, AWU:await-unbind, AWD:await-delete, HLD:held-down

Name: rs1 State: Active Cost: 0 IP:192.168.3.1: 1Mac: 000c.29b6.64de Weight: 1/1 MaxConn: 2000000SrcNAT: cfg, op DstNAT: not-cfg, not-op Serv-Rsts: 0tcp conn rate:udp conn rate = 0:0, max tcp conn rate:max udp conn rate = 0:0BP max local conn configured No: 0 0 0 0 0 0BP max conn percentage configured No: 0 0 0 0 0 0Use local conn : NoSIP current TCP connections = 0

Port St Ms CurConn TotConn Rx-pkts Tx-pkts Rx-octet Tx-octet Reas---- -- -- ------- ------- ------- ------- -------- -------- ----default UNB 0 0 0 0 0 0 0 0http HLD 0 0 0 0 0 0 0 0

ServerIronADX(config)#show server real rs1 dethttp HLD 0 0 0 0 0 0 0 0 max_conn = 10 fail time = 0, Vir IP 192.168.1.2 tcp conn rate:udp conn rate = 0:0, max tcp conn rate:max udp conn rate = 0:0SIP TCP Current Connections = 0 BP max local conn configured No: 0 0 0 0 0 0 BP max conn percentage configured No: 0 0 0 0 0 0 Use local conn : No resp_time = 7 Keepalive(G/L:Off/On):On Status Code(s): default (200-299, 401) HTTP URL: "HEAD /" tcp-age: 30 Hold-down time remaining: 25 second(s)dns ACT 0 0 39 39 45 10151 3972 0

…


Hash-based SLB with server persistence2

Hash-based SLB with server persistenceThis feature provides a persistent hashing mechanism for virtual server ports, which evenly distributes hash assignments and enables a client to always be redirected to the same real server. Command support is also provided to help you manage the introduction of a new server.

This feature enables a client to always be redirected to the same real server. The client will be directed to a new real server only if the assigned real server fails.

By default, SLB uses stateful load balancing for Virtual IP addresses (VIPs). In stateful load balancing, the ServerIron ADX creates session table entries for the connections between the client and the destination (the real server). If multiple real servers are bound to a VIP, then requests from the same client can be serviced by different real servers over a period of time. However, for transaction-oriented systems, a client might need to be serviced by the same real server each time the client makes a request, regardless of the length of time between each request made.

Using the sticky feature, the current maximum persistence possible for Stateful SLB is 20 hours. This setting might not be sufficient for systems that always need the client to be directed to the same real server, unless an event such as real server failure necessitates reassignment of the client to a different server.

Persistent hash table Each virtual server port maintains a persistent hash table consisting of 256 entries. When the ServerIron ADX boots up, all the hash entries in the table are empty (no real server assignments to any of the entries). When a client makes a request to the VIP, the ServerIron ADX calculates a hash value based on the client IP. The hash will be a value between 0 and 255 and will map to one of the entries in the persistent hash table. The ServerIron ADX then retrieves the persistent hash table entry for the calculated hash value. If there is no real server allocated for the table entry, the ServerIron ADX selects a real server for that table entry using the configured SLB predictor. The system will then assign the real server to the table entry, and the client request will be serviced by the real server.

If the client makes another request to the VIP, for example after two days, then the ServerIron ADX will again calculate the hash based on the client IP and retrieve the persistent hash table entry. Because a real server has already been allocated to the persistent hash table entry, the ServerIron ADX will use this real server to service the client request. As an effect, the client will always be directed to the same real server.

Clear vs reassign mechanismsThere are two configurable mechanisms to handle the introduction of a new server through the following options of the port port persist-hash command:

• clear-on-change — Whenever a new server comes up, the entire persistent hash table is cleared and assignments are started afresh. For more information, refer to “Enabling the clear-on-change mechanism” on page 115.

• reassign-on-change — The default. Whenever a new server comes up, the ServerIron ADX calculates the number of hash entries allocated to each existing server. The ServerIron ADX then reassigns some of these entries to the new server. For more information, refer to “Enabling the reassign-on-change mechanism” on page 116.


Hash-based SLB with server persistence 2

Enabling persistent hashingTo enable the persistent hashing (phash) mechanism for a virtual server port, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip vs1ServerIronADX(config-vs-vs1)#port http persist-hash

The reassign-on-change function is selected by default.

Syntax: [no] port port persist-hash [clear-on-change | reassign-on-change]

When persistent hashing is configured for a VIP, the round robin predictor for the VIP is automatically enabled. This default is used to evenly distribute hash assignments. After you enter the port port persist-hash command, the predictor round-robin command automatically appears under the virtual server in the configuration file.

NOTESSL is a special case where sticky automatically gets turned on. If persistent hashing must be configured for port SSL, you need to explicitly turn off sticky on the SSL port using the no port ssl sticky command and then enable persistent hashing for this port.

Enabling the clear-on-change mechanismTo enable the clear-on-change mechanism, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip vs1ServerIronADX(config-vs-vs1)#port http persist-hash clear-on-changeServerIronADX(config-vs-vs1)#end

When the clear-on-change option is set for persistent hashing, the entire persistent hash table is cleared whenever a new server comes up. For example, is shown in the following figure.

Figure 14 shows the persistent hash table for a virtual server port before the rs3 comes up.

FIGURE 14 Hash table before rs3 comes up

Assume the administrator now binds port HTTP of a new real server rs3 to port HTTP of virtual server vs1. When real server rs3 comes up, the entire persistent hash table is cleared.



Figure 15 shows the persistent hash table for a virtual server port after the rs3 comes up.

FIGURE 15 Hash table after rs3 comes up

Enabling the reassign-on-change mechanismTo enable the reassign-on-change mechanism, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip vs1ServerIronADX(config-vs-vs1#port http persist-hash reassign-on-change

When reassign-on-change is enabled (the default), the ServerIron ADX reassigns some of the existing hash table entries on the introduction of a new server.

Configuring the reassign threshold and durationThere are two configurable global parameters related to the reassign mechanism:

• Reassign threshold — When the number of empty hash entries (buckets) in the persistent hash table falls to or below this threshold (less than or equal to), the ServerIron ADX reassigns some of the persistent hash entries on introduction of a new real server. By default, the ServerIron ADX reassigns persistent hash entries to the new real server only if there are no empty persistent hash entries (for example, the default persist hash reassign threshold is 0 percent).

To specify the threshold, enter a command such as the following.

ServerIronADX(config)#server persist-hash-threshold 5

Syntax: [no] server persist-hash-threshold percent-value

The percent-value variable can be any value from 0 through 99.

With the reassign mechanism, if multiple servers come up simultaneously and need reassignment because the number of empty hash table entries is below the reassign threshold, then the ServerIron ADX will clear the persistent hashing table.



• Reassign duration — If the number of empty persistent hash entries is below the reassign threshold, the ServerIron ADX reassigns some of the persistent hash entries over a period of time to the new real server. This duration of time is known as the persist hash reassign duration.

To specify the reassign duration, enter a command such as the following.

ServerIronADX(config)#server persist-hash-reassign-duration 5

This global command is applied to all configured VIP ports that are persist-hash enabled. The ServerIron ADX will complete the reassignment within 2 minutes by default.

Syntax: [no] server persist-hash-reassign-duration value

The value variable can be a time duration from 2 to 30 minutes

Reassignment sequence and exampleThe sequence is performed as follows.

1. When a new server is introduced, the ServerIron ADX calculates how many of the hash table entries in the persistent hash table are empty. If the number is greater than the persist-hash-reassign-threshold, the ServerIron ADX does no reassignment.

If the number of empty hash table entries is less than or equal to the persist hash reassign threshold, the ServerIron ADX proceeds with the reassignment. The system first calculates the total number of active real servers, which includes the new real server.

2. The system calculates the entries per server as follows.

X = entries per server = total assigned hash table entries/number of active real servers

3. The ServerIron ADX attempts to reassign X persistent hash entries to the new real server over the duration specified by the persist-hash-reassign-duration.

The ServerIron ADX will stop reassigning persistent hash entries to the new real server when either of the following occurs:

• The system has finished reassigning X persistent hash entries to the new real server (occurs in the amount of time specified by the persist-hash-reassign-duration)

• The number of persistent hash entries assigned to the new real server is equal to the lowest number of persistent hash entries assigned to any of the existing real servers, whichever happens earlier.



Consider the following reassignment example. Figure 16 shows the hash table before reassignment.

FIGURE 16 Hash table before reassignment

Persistent hash entries have been assigned as follows. Entries 47 to 54 have been assigned to real server rs1. Entries 55 and 56 have been assigned to rs2. All other entries are empty (no real server has been assigned to them).

In this example, the administrator configures a reassign-threshold of 99 percent. That is, whenever the number of empty hash entries falls below 99 percent, the ServerIron ADX will reassign the persistent hash table entries whenever a new real server comes up. The reassign-duration is the default value (2 minutes).

Next, the administrator binds port HTTP of a new real server rs3 to port HTTP of virtual server vs1. When real server rs3 comes up, the ServerIron ADX calculates the number of active real server ports. In this example, the number is 3 (rs1, rs2 and rs3). The system then calculates the number of empty hash table entries. In this example, the number is 246. Because less than 99 percent of the hash table entries are empty, the ServerIron ADX now attempts to reassign some of the persistent hash entries to the new real server rs3.

The ServerIron ADX then calculates entries per server X as follows.

X = total assigned hash table entries/number of active real servers = 10/3 = 3

The ServerIron ADX now attempts to reassign 3 persistent hash entries to the new real server over 2 minutes. The system will stop after it has reassigned 2 entries of real server rs1 to new real server rs3. The reason is that when rs3 is assigned 2 persistent hash entries, the value is equal to the number of entries assigned to existing real server rs2.



Figure 17 shows the persistent hash table after the reassignment.

FIGURE 17 Hash table after reassignment

Keeping the persistent hash table unchangedTo configure the ServerIron ADX not to clear the persistent hashing table when multiple servers come up simultaneously and need reassignment, enter commands such as the following.

SLB-ServerIronADX(config)#server virtual-name-or-ip vs1SLB-ServerIronADX(config-vs-vs1)#port http no-auto-clear-persist-hash-buckets

If this command is configured and multiple servers need reassignment simultaneously, then the ServerIron ADX will leave the persistent hash table unchanged.

Syntax: port port no-auto-clear-persist-hash-buckets

Real server failureIf a real server fails, the ServerIron ADX will remove all assignments of the real server from all persistent hash table entries in the persistent hash table.

For example, consider a virtual server vs1 whose port HTTP is bound to port HTTP of real server rs1 and rs2. Figure 18 shows the persistent hash table for vs1 for port HTTP before server failure.

FIGURE 18 Hash table before server failure

Real server rs1 has been assigned to persistent hash table entries corresponding to hash value 0 and hash value 2. Real server rs2 has been assigned to the entry corresponding to hash value 1. Now assume all other hash table entries have not been assigned to any real servers.



If port HTTP of real server rs1 fails, then the ServerIron ADX will clear assignment of rs1 to the persistent hash entries in the above table. Figure 19 shows the persistent hash table for vs1 for port HTTP after server failure.

FIGURE 19 Hash table after server failure

The ServerIron ADX does not immediately assign a new server to the cleared hash table entries. Instead, the ServerIron ADX will select and assign a real server for these entries using the SLB predictor the next time a client hashes to these hash table entries.

In the previous example, assume a client now makes an HTTP request for virtual server vs1. Assume also the client’s IP address hashes to a value of 2. The ServerIron ADX checks the hash table entry corresponding to hash value 2 in the above persistent hash table. Because no real server is associated with the hash entry, the ServerIron ADX selects a new real server, such as rs2, using the SLB predictor and then assigns the server to the hash table entry. This and subsequent requests from the client will then be serviced by rs2. Figure 20 shows the new real server rs2 to service request to the client.

FIGURE 20 Using rs2 to service requests

Displaying persistent hash table entry and statisticsTo display the persistent hash table entry and statistics for a virtual server, use the rconsole command to get into the BP and enter the following command.

Syntax: show server persist-hash-buckets virtual-server-name

ServerIronADX#show server persist-hash-buckets http-vsVirtual port Persist Hash Buckets:Virtual Server <http-vs> Port <80>: Bucket: Server Hit Bucket: Server Hit 45: http-rs1 1Virtual Server <http-vs> Port <53>: Bucket: Server Hit Bucket: Server Hit 45: dns-ns 2



If you do not specify a virtual server name, all the persistent hash tables for all virtual server ports for all virtual servers will be displayed. Table 7 displays the output field description of show server persist-hash-buckets command.

Clearing the hit count for the persistent hash tableTo clear the hit count for the persistent hash table for a virtual server port, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip http-vsServerIronADX(config-vs-http-vs)#port http clear-persist-hash-statisticsServerIronADX(config-vs-http-vs)#end

Syntax: port port clear-persist-hash-statistics

Clearing the persistent hash tableTo clear the persistent hash table (all assignments and hit counts) for a virtual server port, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip http-vsServerIronADX(config-vs-http-vs)#port http clear-persist-hash-bucketsServerIronADX(config-vs-http-vs)#end

Syntax: port port clear-persist-hash-buckets

Reassigning a persistent hash table entryTo manually reassign a persistent hash table entry to a real server for a specified client IP, enter a command such as the following.

ServerIronADX#show server manual-persist-assign-hash 10.1.1.33 http-vs 80 http-rs1 80Hash bucket for Client IP 10.1.1.33 = 36Server http-rs1 allocation to bucket 36 of specified virtual server for port 80 completed!

Syntax: show server manual-persist-assign-hash client-ip virtual-server-name virtual-port real-server-name real-port

TABLE 7 Output field descriptions of show server persist-hash-buckets command

Field Description

Virtual server Name of the virtual server.

Port Virtual server port.

Bucket Hash value for hash table entry.

Server Real server assigned to the hash table entry.

Hit Number of times the client IP has hashed to this entry and been serviced by the associated real server. It is possible for multiple clients to hash to the same hash entry (bucket).



If you manually assign a real server for a hash table entry for which another real server is currently assigned, the new real server will replace the old real server for the hash entry as follows.

ServerIronADX#show server manual-persist-assign-hash 10.1.1.33 http-vs 80 http-rs2 80Hash bucket for Client IP 10.1.1.33 = 36Replacing current server http-rs1 allocated for hash 36 with server http-rs2Server http-rs2 allocation to bucket 36 of specified virtual server for port 80 completed!

Displaying hash bucket countersYou can display information about hash bucket changes on the ServerIron ADX, through use of the show server proxy keep-alive command. You can use the hash bucket counter information for tracing the reason why a persist based on a hash-to-bucket CSW policy failed during traffic flow. A truncated display is shown with the hash bucket information:

Syntax: show server proxy keep-alive

Table 8 displays the output field description of show server proxy keep-alive command.

TABLE 8 Output field descriptions for hash buckets of show server proxy keep-alive command

Field Description

Current serv is down The current server is down.

Serv exceed max-conn The number of times that the current server exceeds the max-conn configuration.

Lower BP wins The hash table is sync’ed to all BPs. Where another BP assigns the bucket to a different server, the lower BP wins.

ServerIronADX#show server proxy keep-alive

Keep-alive connection statistics:...Hash Bucket Change:

Current serv is down = 1 Serv exceed max-con = 0Lower BP wins = 0

...


SLB spoofing configuration and support 2

SLB spoofing configuration and supportSpoofing is the ServerIron ADX application switch's ability to redirect reverse SLB traffic to the interface from where the actual connection came through, regardless of any other route configured.

When spoofing is enabled for a port on a virtual server, the ServerIron ADX marks the input interface of the connection. Later any response traffic for the session will be forwarded using this information regardless of any other route (like next-hop route, policy based route, default route) configured.

Configuration example:ServerIronADX(config)#server virtual-name-or-ip vip1 10.10.1.100ServerIronADX(config-vs-vip1)#port httpServerIronADX(config-vs-vip1)#port http spoofing

Syntax: [no] port port spoofing

SLB spoofing is supported for all TCP traffic except for complex protocol ports (for example FTP, MMS, RTSP and TFTP).

SLB spoofing is supported for UDP (from 12.3.00 release) with the following limitations.

• UDP spoofing will not work if GSLB is configured.

• UDP spoofing will not work if the dns-udp-count-connection command is configured.

• It is not supported for IMCP response traffic originated from the VIP.

Policy-based SLBPolicy-based server load balancing (PBSLB) is the ServerIron ADX’s ability to direct requests to a server group based on the source IP address (IPv4 or IPv6)of the request.

When policy-based SLB is enabled for a port on a virtual server, the ServerIron ADX examines the source IP address of each new connection sent to the VIP on the port. The ServerIron ADX looks up the source IP address of the request in an internal policy list. The policy list is a table that associates IP addresses with real server groups. If an entry for the IP address is found in the policy list, then the ServerIron ADX forwards the request to the associated real server group. If no entry for the IP address is found, the ServerIron ADX directs the request to a server group specified as the "default" server group.


Policy-based SLB2

Figure 21 shows a sample policy-based SLB configuration.

FIGURE 21 Policy-based SLB configuration

The policy list contains three entries: one associating IP address 10.10.10.1 with Real Server Group 1, another associating network address 10.20.0.0/16 with Real Server Group 2 and a third. associating network address 2001:DB8:300::/64 with Real Server Group 4. In addition, Real Server Group 3 is specified as the default server group.

In this example, policy-based SLB works as follows:

• When a request from address 10.10.10.1 is received on the VIP, the ServerIron ADX forwards the request to one of the load-balanced servers in Real Server Group 1.

• When a request from network 10.20.0.0/16 is received, it is forwarded to the real server in group 2.

• When a request from network 2001:DB8:300::/64 is received, it is forwarded to the real server in group 4.

• When a request from a different address is received, because it does not have an entry in the policy list, it is forwarded to one of the load-balanced real servers in the default server group, which is specified as group 3. Requests for an IPv4 address are sent to the rs4 and requests for an IPv6 address are sent to rs5.


Policy-based SLB 2

NOTES: Consider the followng:

• Policy-based SLB is enabled for individual ports on virtual servers.

• Because policy-based SLB is enabled on a per-VIP basis, some VIPs configured on the ServerIron ADX can have policy-based SLB enabled, while others do not.

• Policy-based SLB can exist on a standalone device or in high-availability configurations, such as active-standby, symmetric, and active-active configurations.

• Policy-based SLB can coexist with other ServerIron ADX features, including FWLB, NAT, and TCS.

• Policy-based SLB cannot coexist on the same VIP with Layer 7 switching features, including URL switching and cookie switching.

Configuring a policy list

A policy list can be created in two ways depending on the number of policies being defined:

• If the number of policies is small, you can create the policy list file using the CLI. Refer to “Creating the policy list for IPv4 using the CLI” and “Creating the policy list for IPv6 using the CLI.”

• If the number of policies is large, you can download the policy list file from a TFTP server or a USB flash. Refer to “Creating the policy list file to dynamically download from a TFTP server or USB flash.”

Creating the policy list for IPv4 using the CLIThe following command can be used to add policies.

ServerIronADX(config)#server pbslb add 10.10.10.1 1

Syntax: server pbslb add ipv4-addr {prefix | netmask [server-group-id]

The ipv4-addr variable can be a complete host address, or a network address followed by IPv4 mask bits. You must specify either a prefix or a netmask.

The server-group-id variable is alphanumeric and refers to one of the real server groups configured on the ServerIron ADX.

For the example shown in “Policy-based SLB configuration” on page 124, the policies can be added as shown in the following.

ServerIronADX(config)#server pbslb add 10.10.10.1 1ServerIronADX(config)#server pbslb add 10.20.0.0/16 2

Creating the policy list for IPv6 using the CLIThe following command can be used to add policies.

ServerIronADX(config)#server pbslb add 2001:DB8:300::/64 4

Syntax: server pbslb add ipv6-addr prefix [server-group-id]

The ipv6-addr variable can be a complete host address, or a network address followed by IPv6 mask bits specified by the prefix variable.



Policy-based SLB2

For the example shown in “Policy-based SLB configuration” on page 124, the policies can be added as shown in the following.

ServerIronADX(config)#server pbslb add 2001:DB8:300::/64

Creating the policy list file to dynamically download from a TFTP server or USB flashTo dynamically download a policy list file from a TFTP server or USB flash, it must be a flat ASCII text file that consists of one or more policy-based SLB entries configured in the following format.

ip-addr [network-mask] [server-group-id]

The ip-addr variable can be a complete host address, or a network address followed by IP mask bits.


For the example shown in “Policy-based SLB configuration” on page 124, the policies would be defined as shown in the following.

10.10.10.1 110.20.0.0/16 22001:DB8:300::/64 4

The policy list file created in the format defined above can be transferred to the ServerIron ADX from either a TFTP server or through a USB flash drive. A single download file should contain all IPv4 and IPv6 entries. These entries can be in any order.

NOTEDownloading a new file overwrites the existing policy list file on a ServerIron ADX. Consequently any entries that are not in the most recent download will be lost.

Dynamically downloading a policy list using TFTPWhen a policy list is created, as described in “Creating the policy list file to dynamically download from a TFTP server or USB flash,” the following command can be used to download the file from a TFTP server.

ServerIronADX(config)#server pbslb tftp 192.168.9.210 policy-list.txt 5

When you enter this command, the downloaded policy list file immediately replaces the entries in the ServerIron ADX’s policy-based SLB configuration.

Syntax: server pbslb tftp tftp-server-ip-addr filename retry-count

The tftp-server-ip-addr variable specifies the IP address of the TFTP server.

The filename variable specifies the name of the policy list file.

The retry-count variable specifies the number of times that the ServerIron ADX retries the download if the first attempt is not successful.

Dynamically downloading a policy list using an external USB flash driveThe following command can be used to download the policy list file from an external USB flash drive.

ServerIronADX(config)#server pbslb /usb1/policy-list.txt 5


Policy-based SLB 2

NOTEThe filename must begin with /usb1/ when downloading from and external USB flash drive.


Syntax: server pbslb usb-filename

The usb-filename variable specifies the name of the policy list file. It must begin with “/usb1/”.

Downloading a policy list using the internal USB flash driveTo be able to download a policy list file form the internal USB drive, you must first download the file from the external USB drive to the internal USB using the following command.

ServerIronADX#copy usb1 usb0 policy-list.txt policy-list.txt

Syntax: copy usb1 usb0 source-filename destination-filename

The source-filename variable specifies the name of the file that is being copied from the external USB flash drive to the internal USB flash drive.

The destination-filename variable specifies the name of the file once it is copied to the internal USB flash drive.

After using the copy usb1 usb0 command to copy the file to the internal USB flash drive, you can use the following command to download the policy list from the internal USB flash drive.

ServerIronADX(config)#server pbslb /usb0/policy-list.txt


Syntax: server pbslb usb-filename

The usb-filename variable specifies the name of the policy list file. It must begin with “/usb0/”.

Redirecting traffic to the default group during downloadThe ServerIron ADX supports seamless download (or no blocking of VIP traffic while a policy list is being downloaded) only when the number of PBSLB entries do not exceed the following: for IPv4 - 1,000,000 entries, for IPv6 256,000 entries. A ServerIron ADX maintains two separate tables in memory: one for the existing list and one for the new list that is being downloaded. After the new list is completely downloaded, it is swapped with the existing list. This method allows for the new policy list to take effect immediately without affecting the VIP traffic during the download.

NOTEThis redirect method only applies when the maximum number of PBSLB entries has not been increased to over 1,000,000 for IPv4 or 256,000 for IPv4 through use of the server pbslb max-entries command.

For policy list files that contain more than 1,000,000 entries, all VIP traffic will be blocked during the download and will resume only after the policy list file is completely downloaded. To be able to send VIP traffic to the default server group instead of blocking it during download, enable the server pbslb send-to-default-group-during-download feature.

There are three steps to turn on this feature.

1. Create a PBSLB default group-ID.

2. Assign real server ports to the default group.


Policy-based SLB2

3. Enable send-to-default-group-during-download.

Creating a PBSLB default group for IPv4To create a PBSLB default group, enter a command such as the following.

ServerIronADX(config)#server pbslb default-group-id ipv4 4

Syntax: [no] server pbslb default-group-id ipv4 group-id

Creating a PBSLB default group for IPv6To create a PBSLB default group, enter a command such as the following.


Syntax: [no] server pbslb default-group-id ipv6 group-id

Assigning real server ports to default groupA default group can contain one or more real servers. If there is more than one real server in a default group, requests are load balanced across all the servers in the group. To assign real servers to the default group, enter commands such as the following.

ServerIronADX(config)#server real-name rs1 10.95.7.14ServerIronADX(config-rs-rs1)#port http group-id 4 4ServerIronADX(config-rs-rs1)#exit

Enabling pbslb send-to-default-group-during-downloadTo enable send-to-default-group-during-download, enter a command such as the following.

ServerIronADX(config)#server pbslb send-to-default-group-during-download

Syntax: [no] server pbslb send-to-default-group-during-download

NOTE You configure this command only if you have increased the maximum number of PBSLB entries over the default number.

Specifying the maximum number of entries

By default, a policy-based SLB configuration can have up to 25,000 IPv4 and 25,000 IPv6 entries. You can optionally specify the maximum number of entries allowed for a policy-based SLB configuration.

For example, to specify 40,000 as the maximum number of IPv4 entries for policy-based SLB, enter the following command.

ServerIronADX(config)#server pbslb max-entries ipv4 40000

To specify 50,000 as the maximum number of IPv6 entries for policy-based SLB, enter the following command.

ServerIronADX(config)#server pbslb max-entries ipv6 50000

Syntax: server pbslb max-entries { ipv4 | ipv6 } max-number

The max-number variable specifies the maximum number of PBSLB entries you want to configure. The maximum number of IPv4 entries that ServerIron ADX supports is 10,000,000. The maximum number of IPv6 PBSLB entries that ServerIron ADX supports is 1,000,000.


Policy-based SLB 2

After you enter this command and save the configuration, you must reload the software for the new maximum limit to take effect.

Deleting an entry from the policy list for IPv4

To delete an entry from the policy list, enter the following command.

ServerIronADX(config)#server pbslb delete 10.10.10.1/24 4

Syntax: server pbslb delete ipv4-addr { netmask | prefix [server-group-id]

The ipv4-addr variable specifies the IPv4 entry that you want to delete from the policy list. You must specify either a prefix or a netmask.


Deleting an entry from the policy list for IPv6

To delete an entry from the policy list, enter the following command.

ServerIronADX(config)#server pbslb delete 2001:DB8:300::1/128

Syntax: server pbslb delete ipv6-addr prefix [server-group-id]

The ipv6-addr variable specifies the IPv6 entry that you want to delete from the policy list. You must specify a prefix.


Deleting an entire PBSLB list

To delete the entire PBSLB list, enter a command such as the following.

NOTEThis command will delete all the entries in the PBSLB list. You can enter the show pbslb all 0 command to first display the contents of the list before deleting the entire list.

ServerIronADX(config)#server pbslb delete all ipv6The whole IPv6 table of PBSLB has been deleted.

Syntax: server pbslb delete all {ipv6 | ipv4}

The ipv4 keyword directs the ServerIron ADX to delete the entire IPv4 PBSLB list.

The ipv6 keyword directs the ServerIron ADX to delete the entire IPv6 PBSLB list.

Copying a policy list to a file on TFTP server

To copy the currently loaded policy list from the ServerIron ADX to a file on a TFTP server, enter a command such as the following.

ServerIronADX#copy pbslb-running-config tftp 192.168.9.210 policy-list.txt

Syntax: copy pbslb-running-config tftp tftp-server-ip-addr filename

The tftp-server-ip-addr variable is the IP address of the TFTP server.


Policy-based SLB2

The filename variable is the name the policy list file will be saved as.

Writing the policy list to flash memory

By default, the policy list is not saved to flash memory when you enter the write memory command.To write the policy list to flash memory, enter the following command.

ServerIronADX(config)#server pbslb enable-config-gen

The next time the ServerIron ADX is booted, the policy list will appear in the running-config.

Syntax: server pbslb enable-config-gen

NOTEThe ServerIron ADX is unable to copy a policy list with more than 1,000 entries to Flash.

Specifying a default server group

When a new connection is sent to a VIP where policy-based SLB is enabled, if no entry for the source IP address is found in the policy list, the ServerIron ADX directs the request to a server group specified as the "default" server group.

To specify a server group as the default server group, enter a command such as the following.


Syntax: server pbslb default-group-id { ipv4 | ipv6 } group-id

The ipv4 parameter directs the ServerIron ADX to direct the request to an IPv4 server group.

The ipv6 parameter directs the ServerIron ADX to direct the request to an IPv6 server group.


Assigning real servers to server groups

The policy list associates source IP addresses with real server group IDs. To configure policy-based SLB, you assign real servers to real server groups.

A real server group can contain one or more real servers. If there is more than one real server in a server group, requests are load balanced across all the servers in the group. To assign real servers to server groups, establish the IP address of each real server and specify the server groups to which it belongs.

For example, to configure real server rs1 in Figure 21 on page 124, enter commands such as the following.

ServerIronADX(config)#server real rs1 10.95.7.1ServerIronADX(config-rs-rs1)#port http group-id 1 1ServerIronADX(config-rs-rs1)#exit

Syntax: [no] server real real-server-name ip-addr

Syntax: [no] port port group-id server-group-id-pairs

In this example, the server real command defines a real server called rs1 with an IP address of 10.95.7.1.


Policy-based SLB 2

The port http group-id command indicates the server groups to which the real server belongs. The server group is expressed as a pair of numbers, indicating a range of real server group IDs. The first number is the lowest-numbered server group ID, and the second is the highest-numbered server group ID. For example, if a real server belongs only to the server group with ID = 1, the last two numbers in the port http group-id command would be 1 1. (Note the space between the two numbers.) If a real server belongs to server groups 1 through 10, the last two numbers in the command would be 1 10. Valid numbers for server group IDs are from 0 through 1023.

To include a real server in groups that are not consecutively numbered, enter up to four server group ID pairs. For example, to include a real server in groups 1–5 and 11–15, enter the following command.

ServerIronADX(config-rs-rs1)#port http group-id 1 5 11 15

You can also specify the server group ID pairs on separate lines; for example.

ServerIronADX(config-rs-rs1)#port http group-id 1 5ServerIronADX(config-rs-rs1)#port http group-id 11 15

The configuration for the remaining real servers in Figure 21 on page 124 is shown below. These commands place real server rs2 in server group ID = 1 (along with real server rs1), real server rs3 in server group ID = 2, and real servers rs4 and rs5 in server group ID = 3.

ServerIronADX(config)#server real rs2 10.95.7.2ServerIronADX(config-rs-rs2)#port http group-id 1 1ServerIronADX(config-rs-rs2)#exitServerIronADX(config)#server real rs3 10.95.7.3ServerIronADX(config-rs-rs3)#port http group-id 2 2ServerIronADX(config-rs-rs3)#exitServerIronADX(config)#server real rs4 10.95.7.4ServerIronADX(config-rs-rs4)#port http group-id 3 3ServerIronADX(config-rs-rs4)#exitServerIronADX(config)#server real rs5 2001:db8::1ServerIronADX(config-rs-rs5)#port http group-id 3 3ServerIronADX(config-rs-rs5)#exitServerIronADX(config)#server real rs6 2001:db8:400::1ServerIronADX(config-rs-rs5)#port http group-id 4 4ServerIronADX(config-rs-rs5)#exitServerIronADX(config)#server real rs7 2001:db8:400::2ServerIronADX(config-rs-rs5)#port http group-id 4 4ServerIronADX(config-rs-rs5)#exit

Enabling PBSLB for a port on a virtual server

To enable policy-based SLB on a VIP for Figure 21 on page 124, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip mysite 10.157.22.63ServerIronADX(config-vs-mysite)#port httpServerIronADX(config-vs-mysite)#port http sw-l4-pbslbServerIronADX(config-vs-mysite)#bind http rs1 http rs2 http rs3 http rs4 http rs5 http

Syntax: [no] port port sw-l4-pbslb


Policy-based SLB2

Deleting existing PBSLB sessions

By default, when a PBSLB server group configuration changes, the client sessions with that group remain open. For example, if a client has sessions associated with Group A, but Group A’s configuration changes and moves the client sessions to Group B, the sessions with Group A are still open. You can change this behavior by enabling the scan-session-table-after-config-change feature. With this feature enabled, old connections are deleted and a new connection is set up with a new group whenever a PBSLB server's configuration changes.

To enable this feature, enter the following command.

ServerIronADX(config)#server pbslb scan-session-table-after-config-change

Syntax: [no] server pbslb scan-session-table-after-config-change

Use the no server pbslb scan-session-table-after-config-change command to disable this feature. The feature is disabled by default.

PBSLB pool failsafe group

The PBSLB pool failsafe group feature allows a ServerIron ADX to direct traffic away from a given server pool to a "default pool" in situations where the servers in the server pool become unavailable.

Overview of PBSLB pool failsafe groupWhen PBSLB is used to filter traffic based on source IP address, a ServerIron ADX looks up a group id for the client to forward the incoming request to. If all the servers in the group fail, the ServerIron ADX sends a TCP reset to the client, causing the request to fail. This feature allows you to configure a failsafe group, which will be used to forward traffic, in case the group designated for a client source-ip address fails. The following section outlines the behavior of this feature in two scenarios.

For IP addresses present in the PBSLB list:• If the group-id is 0 (deny group), the traffic is denied (RST in case of TCP and drop in case of

udp).

• If the group-id is not 0, if the servers are healthy, and the max-conn limit is not reached, traffic is load balanced among servers as per predictor.

• If all servers of the group are in a failed state or the max-conn limit is reached, traffic is load balanced among "failsafe" group servers.

• If all of the servers of the "failsafe" group are in a failed state or the max-conn limit is reached, traffic is denied (RST in case of TCP and drop in case of UDP).

For IP addresses not present in the PBSLB list:• If the default-group-id is not configured or is configured as 0 (deny group), traffic is denied.

• If the default-group-id is configured, traffic is load balanced among default-group servers as per predictor.

• If all of the servers of the default-group are in a failed state or the max-conn limit is reached on all servers, the traffic is load balanced among "failsafe" group servers.

• If all of the servers of the failsafe group are in a failed state or the max-conn limit is reached, the traffic is denied.


Policy-based SLB 2

Command line interfaceThere are three steps to enable this feature.

1. Create a PBSLB failsafe group ID.

2. Assign real server ports to a failsafe group.

3. Enable PBSLB on a VIP port.

Creating a PBSLB failsafe groupTo create a PBSLB failsafe group, enter a command such as the following.

ServerIronADX(config)#server pbslb failsafe-group-id ipv4 2

Syntax: [no] server pbslb failsafe-group-id { ipv4 | ipv6 } group-id

The ipv4 parameter directs the ServerIron ADX to create an IPv4 failsafe group.

The ipv6 parameter directs the ServerIron ADX to create an IPv6 failsafe group.

The group-id variable is alphanumeric and refers to one of the real server groups configured on the ServerIron ADX.

Assigning real server ports to a failsafe groupA failsafe group can contain one or more real servers. If there is more than one real server in a failsafe group, requests are load balanced across all the servers in the group. To assign real servers to the failsafe group, enter commands such as the following.

ServerIronADX(config)#server real-name rs1 10.95.7.1ServerIronADX(config-rs-rs1)#port http group-id 2 2ServerIronADX(config-rs-rs1)#exit

Enabling PBSLB on a VIP portTo enable PBSLB on a VIP port, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip mysite 10.157.22.63ServerIronADX(config-vs-mysite)#port httpServerIronADX(config-vs-mysite)#port http sw-l4-pbslbServerIronADX(config-vs-mysite)#bind http rs1 http

Using show commandsTo view the number of requests forwarded to the failsafe server group, enter the following command.

ServerIronADX#show pblsb failsafe ipv4

Syntax: show pbslb failsafe { ipv4 | ipv6}

To clear the PBSLB failsafe counter, enter the following command.

ServerIronADX#clear pbslb failsafe

Syntax: clear pbslb failsafe


Policy-based SLB2

Auto Download of PBSLB list

Policy Based Load Balancing (PBSLB) Auto Download allows you to automatically download a list of policies to the ServerIron at a scheduled interval or a specific time of day. This automation precludes the need to write scripts and cron jobs. Using PSLB Auto Download, you can regularly upload an updated PBSLB list to the ServerIron on a pre-determined schedule.

NOTEThe server pbslb tftp command must be configured before the server pbslb time-of-day or server pbslb download-interval command, so the ServerIron ADX knows which server and file name to use in the download.

NOTEThe PBSLB time-of-day granularity is in minutes, so seconds are ignored in the configuration. For example, if you enter time as 16:35:30, it is taken as 16:35:00.

Configuring PBSLB download intervalTo configure the ServerIron ADX to download a PBSLB list at a periodic interval, use commands similar to the following.

ServerIronADX(config)#server pbslb tftp 10.10.1.101 iplist.txt 2ServerIronADX(config)#server pbslb download-interval 20

Syntax: server pbslb download-interval interval-in-minutes

In this example, the ServerIron downloads the list in iplist.txt from server 10.10.1.101 once every 20 minutes. If it encounters an error, it retries two times.

Configuring PBSLB time of dayTo configure the ServerIron to download a PBSLB list at a specified time, use commands similar to the following.

NOTEThe SNTP clock must be set for this command to work.

ServerIronADX(config)#server pbslb tftp 10.10.1.101 iplist.txt 2ServerIronADX(config)#server pbslb time-of-day 15:30:00 16:00:00

Syntax: server pbslb time-of-day time-in-hh:mm:ss

In this example, the ServerIron ADX downloads the PBSLB list at 3:30 pm and 4:00 pm every day until the command is reset. You can configure a maximum of five time-of-day parameters.

PBSLB syslog messages

Messages similar to the following appear whenever autodownload PBSLB is executed.

Aug 15 21:23:59:I:PBSLB config file 5mil-2.txt downloaded from TFTP server 172.20.1.6 -->

The preceding line indicates success.

Aug 16 13:30:03:A:FAILED to download PBSLB config file 5mil-2.txt from TFTP server 172.20.1.6 -->

The preceding line indicates failure.


Policy-based SLB 2

Aug 16 14:20:59:W:RETRY download of PBSLB config file 5mil-2.txt from TFTP server 172.20.1.6 -->

The preceding line indicates a retry.

Displaying PBSLB entries

You can display one or more entries in the currently loaded policy list.

To display an individual policy list entry, enter a command such as the following.

ServerIronADX#show pbslb 2001:db8::1IP address Mask Server Group ID 2001:db8::1 128 11

Syntax: show pbslb ip-address

The ip-address variable specifies the IPv4 or IPv6 address of the entry in the currently loaded policy list that you want to display.

The show pbslb command displays the entry in the policy list that corresponds to the specified IP address. If no entry is found for the specified IP address, no output is displayed.

To display multiple entries in the policy list, enter a command such as the following.

ServerIronADX#show pbslb all ipv6 10Max Count: 1000000 Total Count: 2IP address Mask Server Group ID2001:db8::1 128 112001:db8::2 128 12

Syntax: show pbslb all {ipv4 | ipv6} index

The show pbslb all command displays 20 entries in the policy list, starting from the point specified with the index variable. In the example, 20 entries in the policy list are displayed, starting from the 100th entry.

The ipv4 parameter directs the ServerIron ADX to display IPv4 entries.

The ipv6 parameter directs the ServerIron ADX to display IPv6 entries.

Displaying PBSLB group entries

You can display IPv6 entries in the currently loaded policy list for a specified group as shown.

ServerIronADX#show pbslb group 11 ipv6 40 IP address Mask Server Group ID 2001:db8::1 128 11

Syntax: show pbslb group group-id ipv6 index

The group-id variable is alphanumeric and refers to one of the real server groups configured on the ServerIron ADX.

The show pbslb group command displays entries in the policy list, starting from the point specified with the index variable.


Policy-based SLB2

Packet trace

When a policy list file is downloaded to the ServerIron ADX, messages to indicate download progress are printed on the console. By default, when a policy list file is downloaded through a Telnet or SSH session to the ServerIron ADX, these messages do not appear on the Telnet or SSH session. To monitor the download progress on a Telnet session, you need to enable packet trace using the ptrace term command in the Telnet session.

ServerIronADX#ptrace termdebug output is now sent to this terminal

Syntax: ptrace term

When you enter the ptrace term command on a Telnet session, the ServerIron ADX redirects the log output for both the debug and ptrace commands to this session.

NOTEYou can only use the ptrace term command on a console or Telnet session. The ptrace term command is not supported on SSH sessions. To redirect the output back to the console or to a different Telnet session, enter the ptrace term command in that session.

ServerIronADX(config)#server pbslb tftp 10.1.1.1pbslb/pbslb2M.txt 1 Download of pbslb config from TFTP server is initiated..SLB-telnet@ServerIronADX(config)#............................................................................Download of pbslb config from TFTP server is done.TFTP file size = 27718556, Entry count = 1000000, Parse error = 0, Tablefull error 1000000 Resetting pbslb trie Processing PBSLB entries.......................................PBSLB processing done BP sync msg = 200, BP Sync fail = 0Duplicates = 0, Alloc err = 0, Full err = 0, Unknown err = 0

TABLE 9 Error messages

Message Description

BP sync msg The number of messages that it took for the MP to synch the downloaded PBSLB table to the BP (The download itself is staggered, so it is done in multiple passes).

BP Sync fail The number of messages (mentioned above) that failed successful transmission. In the event of a failure, the message is sent again.If BP sync fails, the MP will try to push down the PBSLB table to the BPs again after 100 ms. This process continues until the BP synch is completely successful. On the BP, the PBSLB tree is not populated until the download is totally successful.

Alloc err The number of times the ServerIron ADX was unsuccessful in allocating memory for the PBSLB table. The device tries to allocate the entire table at once, so if there is an error, this counter can only show a value of 1.


Miscellaneous options 2

Miscellaneous options

Changing a real server’s IP addressThe ServerIron ADX enables you to easily change a real server’s IP address, even when the real server is active. This capability is useful when you want to perform some maintenance on the real server (either the server itself or the server’s configuration on the ServerIron ADX) or when the network topology has changed.

By default, when you change a server’s IP address, the ServerIron ADX performs the change gracefully, as follows:

• Existing connections are allowed to continue on the old IP address until they terminate normally.

• New client requests are sent to the new IP address.

Optionally, you can force all existing connections to be reset instead of waiting for them to terminate normally. When you force the connections to be reset, the ServerIron ADX immediately resets a connection when it receives client data for the connection.

To change a real server’s IP address, enter commands such as the following.

ServerIronADX(config)#server real rs1ServerIronADX(config-rs-rs1)#ip-address 10.6.7.8

Syntax: [no] ip-address ip-addr [force-shutdown]

The ip-addr variable specifies the real server’s new IP address.

The force-shutdown parameter immediately resets a client’s connection to the IP address when the ServerIron ADX receives TCP data from the client. By default, the ServerIron ADX allows existing connections to terminate normally following the address change.

Full err The number of times the ServerIron ADX could not add a new PBSLB entry to the table because the PBSLB is already full. This value should indicate the number by which the downloaded pbslb table size exceeds the value that the ServerIron ADX supports.When the PBSLB list is downloaded, it is first populated into a flat table that does not have any hierarchy. After populating this table, the MP will construct the DP table to actually store the PBSLB entries for later lookups. Even when the MP synchs the PBSLB info to the BPs, it is the flat table that is pushed down and not the DP table.Full error refers to those error cases where new entries cannot be added to the DP table because the tree is already full. Table full error refers to those error cases where no more entries can be added to the flat table because the flat table is filled up.

Unknown err Is used to catch miscellaneous unexpected errors. For example, if the download buffer of the PBSLB table from MP to BP is corrupted. Another example is when we try to add an entry to the tree and the entry cannot be added due to an unexpected error.

TABLE 9 Error messages (Continued)

Message Description


Miscellaneous options2

Adding a descriptionYou can add a description to a real server, virtual server, firewall, or cache. The description appears in the output of show commands and in the running-config and startup-config files.

To add a description, enter commands such as the following.

ServerIronADX(config)#server real RS20 10.2.3.4ServerIronADX(config-rs-RS20)#description "Real Server #20"

Syntax: [no] description “text"

Configuring a local or remote real serverWhen you define a real server, you specify whether the real server is local or remote:

• Local – A local server is one that is connected to the ServerIron ADX at Layer 2. The ServerIron ADX uses local servers for regular load balancing.

• Remote – A remote server is one that is connected to the ServerIron ADX through one or more router hops. The ServerIron ADX uses remote servers only if all the local servers are unavailable.

NOTETo use a remote server for regular load balancing, refer to “Primary and backup servers” on page 76.

Defining the maximum number of connectionsYou can limit the maximum number of sessions the ServerIron ADX will maintain in its session table for each barrel processor of a real server. By setting a limit for each barrel processor of a real server, you can avoid a condition where the capacity threshold of the real server is exceeded.

When a barrel processor of a real server reaches the maximum defined connection threshold, an SNMP trap is sent. When all the barrel processors of a real server pool reach their maximum connection threshold, additional TCP or UDP packets are dropped, and an ICMP destination unreachable message is sent.

Up to one million total sessions are supported on the ServerIron ADX. This is also the default maximum connection value for real servers.

To modify the maximum connections supported for a specific real server, enter commands such as the following.

ServerIronADX(config)#server real Web1ServerIronADX(config-rs-Web1)#max-conn 145000ServerIronADX(config-rs-Web4)#endServerIronADX#write mem

Syntax: [no] max-conn 1-2000000

You can also limit the maximum number of connections for individual application ports on a real server.

For example, to limit the number of FTP connections on real server Web1 to 10, enter the following commands.

ServerIronADX(config)#server real Web1ServerIronADX(config-rs-Web1)#port ftp max-conn 10



Syntax: [no] port port max-conn number

NOTEFor FTP (Port 21), the number of current connections is equal to the number of control connections, plus any data connections opened during the session. For example, logging on to an FTP site (the control connection) and transferring a file from the FTP site equal two connections. In Passive mode, the FTP data connection is initiated from the client side. Although there is only one control connection, additional operations performed while you are logged on can consume all the FTP connections allowed. In Active mode, the FTP data connection is initiated from the server side. In Active mode, the server to client connection is not counted towards max-conn value though they are still counted as current connections on the server. When the current connection counter is higher than the max-conn value, any new connections from client to real server are dropped as the max-conn value is reached.

NOTEIf you use the max-conn command for a firewall, the command specifies the maximum permissible number of connections that can be initiated from this ServerIron ADX's direction on the firewall paths. The max-conn command does not limit the total number of connections that can exist on the ServerIron ADX, which includes connections that come from the ServerIron ADXs at the other ends of the firewall paths. For Firewall Load Balancing (FWLB), the fw-exceed-max-drop command restricts the total number of connections that can exist on the ServerIron ADX.

Setting a logging threshold for connection rateYou can set a threshold on the ServerIron ADX to send a log message for the following connection rates:

• The maximum number of sessions the ServerIron ADX maintains in its session table for all barrel processors or a real server pool. The number is set as described in “Defining the maximum number of connections” on page 138. This rate is set per real server.

• The maximum number of new TCP connections per-second allowed on a real server. The number is set as described in “Configuring the connection rate” on page 146. This rate is set per real server.

• The maximum number of UDP connections per-second allowed on a real server. The number is set as described in “Configuring the connection rate” on page 146. This rate is set per real server.

Using the logging threshold feature, you can set a percentage threshold for each of these connection rates that generates a log message. The rate can be set globally to apply for each real server or locally to apply to an individual real server. The local real server value has a higher precedence level than the global value. Also, because there is no default level, a log message will not be generated unless these thresholds are applied either globally or locally.

Example

The maximum number of connections for real server “Web4” is set to 2000. The global logging threshold for maximum connections is set to 80 percent and the local logging threshold is set for “Web4” is set to 70 percent.

When the number of connections at “Web4” reaches 1400 a warning log will be generated. This is because 1400 is 70% of the 2000 limit set for “Web4”.



Setting the logging threshold for maximum connections

You can set a percentage value (either globally or locally per real server) for the percentage of the value set for maximum connections that causes the ServerIron ADX to send a warning log message.

The following example sets the value to 70 percent at the global level.

ServerIronADX(config)#server conn-limit send-log-threshold for-max-conn 70

Syntax: [no] server conn-limit send-log-threshold for-max-conn percentage

The following example sets the value to 70 percent at the local level for the “Web1” real server.

ServerIronADX(config)#server real Web1ServerIronADX(config-rs-Web1)#conn-limit send-log-threshold for-max-conn 80ServerIronADX(config-rs-Web1)#endServerIronADX#

Syntax: [no] conn-limit send-log-threshold for-max-conn percentage

The percentage variable specifies the percentage of the configured maximum number of connections that causes the log message to be sent. A percentage value from 1 - 100 can be configured. If both a global and local (per real server) values are configured, the local value has precedence. If only a global value is configured, it will apply individually to each real server. If no value is configured either globally or locally, no warning log message is sent.

The no conn-limit send-log-threshold for-max-conn command returns the operation to the default behavior. If no value is configured either globally or locally, no warning log message is sent.

Setting the logging threshold for the TCP connection rate

You can set a percentage value (either globally or locally per real server) for the percentage of the value configured for the maximum number of TCP connections-per-second that causes the ServerIron ADX to send a warning log message.

The following example sets the value to 80 percent at the global level.

ServerIronADX(config)#server conn-limit send-log-threshold for-tcp-conn-rate 80

Syntax: [no] server conn-limit send-log-threshold for-tcp-conn-rate percentage

The following example sets the value to 90 percent for the “Web2” real server.

ServerIronADX(config)#server real Web2ServerIronADX(config-rs-Web2)#conn-limit send-log-threshold for-tcp-conn-rate 90ServerIronADX(config-rs-Web2)#endServerIronADX#

Syntax: [no] conn-limit send-log-threshold for-tcp-conn-rate percentage

The percentage variable specifies the percentage of the configured rate per second of TCP connections to a real server that causes the log message to be sent. A percentage value from 1 - 100 can be configured. If both a global and local (per real server) values are configured, the local value has precedence. If only a global value is configured, it will apply individually to each real server. If no value is configured either globally or locally, no warning log message is sent.

Using the no conn-limit send-log-threshold for-tcp-conn-rate command returns the operation to the default behavior. If no value is configured either globally or locally, no warning log message is sent.



Setting the logging threshold for the UDP connection rate

You can set a percentage value (either globally or locally per real server) for the percentage of the value configured for the maximum number of UDP connections-per-second that causes the ServerIron ADX to send a log message.

The following example sets the global value to 60 percent.

ServerIronADX(config)#server conn-limit send-log-threshold for-udp-conn-rate 60

Syntax: [no] server conn-limit send-log-threshold for-tcp-conn-rate percentage

The following example sets the value to 80 percent locally for the “Web3” real server.

ServerIronADX(config)#server real Web3ServerIronADX(config-rs-Web3)#conn-limit send-log-threshold for-udp-conn-rate 80ServerIronADX(config-rs-Web3)#endServerIronADX#

Syntax: [no] conn-limit send-log-threshold for-udp-conn-rate percentage

The percentage variable specifies the percentage of the configured rate per second of UDP connections to a real server that causes the log message to be sent. A percentage value from 1 - 100 can be configured. If both a global and local (per real server) values are configured, the local value has precedence. If only a global value is configured, it will apply individually to each real server. If no value is configured either globally or locally, no warning log message is sent.

Using the no conn-limit send-log-threshold for-udp-conn-rate command returns command returns the operation to the default behavior. If no value is configured either globally or locally, no warning log message is sent.

Configuring a TCP MSS value at the global levelThe default TCP MSS value configured on a ServerIron ADX is 1460 Bytes. This value can be changed globally as shown in the following.

ServerIronADX(config)#tcp-mss 4000

Syntax: [no] tcp-mss mss-value

The mss-value variable specifies the global MSS value. This value can be from 576 to 9176.

Configuring a TCP MSS value for a virtual serverThe default TCP MSS value configured on a ServerIron ADX is 1460 Bytes. This value can be changed per virtual server as shown in the following.

ServerIronADX(config)#server virtual-name-or-ip v1ServerIronADX(config-vs-v1)#tcp-mss 4000


The mss-value variable specifies MSS value for all the real servers bound to the specified virtual server. This value can be from 576 to 9176.



Configuring a TCP MSS value at the virtual server port levelThe default TCP MSS value configured on a ServerIron ADX is 1460 Bytes. This value can be changed per virtual server port as shown in the following.

ServerIronADX(config)#server virtual-name-or-ip v1ServerIronADX(config-vs-v1)#port http tcp-mss 4000

Syntax: [no] port virtual-server-port tcp-mss mss-value

The virtual-server-port variable specifies the TCP port that the MSS value will be applied to.

The mss-value variable specifies the MSS value for all the real server ports bound to the specified virtual server port. This value can be from 576 to 9176.

Configuring a TCP MSS value at the TCP profile levelThe default TCP MSS value configured on a ServerIron ADX is 1460 Bytes. This value can be changed per TCP profile as shown in the following.

ServerIronADX(config)#tcp profile tcp1ServerIronADX(config-tcp-profile-tcp1)#tcp-mss 4000


The mss-value variable specifies the MSS value for all the real servers bound to the specified virtual server configured with the specific TCP profile. This value can be from 576 to 9176.

Support for TCP Window Scale option in TCP headerStarting with the ServerIron ADX release 12.4.00f, the TCP window scale option in TCP header feature is supported. This feature optionally increases the definition of the maximum TCP window from 16 bits (65535) bytes by a window scale factor, to a theoretical maximum of (8388480 bytes). However, this theoretical value is limited by the maximum RX TCP buffer size of 3145278 bytes.

If this feature is not enabled, the maximum TCP window remains at 65535 bytes.

The window scale factor is expressed as a shift count - a power of 2. When enabled, the range of this count is from 1 to 7, i.e., from 2 to the power of 1 to 2 to the power of 7. Zero is the value of the default shift count, when TCP window scale is not specified

NOTEThe TCP window scale option appears in the SYN segment. Both ends of a TCP connection must send this option in their SYN segment. Otherwise window scaling is not enabled.

Configuring TCP window scale option

To configure the TCP window scale option in the TCP header and change the receive and transmit buffer sizes, enter the following commands at the tcp profile configuration level as shown in the example:

ServerIronADX(config)# tcp profile sampleServerIronADX(config-tcp-sample)# tcp-wnd-scale 1ServerIronADX(config-tcp-sample)# rxbuf-size 3145278ServerIronADX(config-tcp-sample)# txbuf-size 3145278



Syntax: [no] tcp-wnd-scale tcp-wnd-scale

The tcp-wnd-scale variable specifies the TCP window scale factor from 1 to 7, the default is 0.

Syntax: [no] rxbuf-size rxbuf-size

The rxbuf-size variable specifies maximum TCP receive buffer size. Enter an integer from 0 to 3145278. The default is 0.

Syntax: [no] txbuf-size txbuf-size

The txbuf-size variable specifies maximum TCP transmit buffer size. Enter an integer from 0 to 3145278. The default is 0.

For example, to display the TCP profile named sample, enter the following show tcp profile command:

ServerIronADX# show tcp profile sampleTCP profile: sample

TCP Rx Buffer Size : 314278TCP Tx Buffer Size : 314278TCP Window scale factor : 1

Syntax: show tcp profile name-of-TCP-profile

Binding a TCP profile to a virtual port and response rewrite policyYou can bind a TCP profile to a virtual port and response rewrite policy as shown in the following.

ServerIronADX(config)#server virtual-name-or-ip v1ServerIronADX(config-vs-v1)#port http response-rewrite-policy resp-1 tcp1

Syntax: [no] port virtual-port response-rewrite-policy response-rewrite-policy-name tcp-profile-name

The virtual-port variable specifies the TCP port that the specified TCP policy will be bound to.

The response-rewrite-policy-name variable specifies the response rewrite policy that the specified TCP policy will be bound to.

The tcp-profile-name variable specifies the TCP policy that the specified response rewrite policy and virtual port will be bound to.

Configuring jumbo frame supportBy default, the ServerIron ADX supports an IP Maximum Transmission Unit (MTU) frame size of 1518 bytes. Jumbo frames enable the ServerIron ADX to handle packet sizes of up to 9216 bytes.

Jumbo frames are supported for both IPv4 and IPv6 traffic in server load balancing, transparent cache switching, and firewall load balancing environments.

IP MTU values can be set globally and at the virtual server level. The frame size configured with these commands are supported for both pass-through traffic via the Management Processor and traffic switched within the ServerIron ADX.

You must reboot the ServerIron ADX when support for IPv4 or IPv6 jumbo frames are enabled or disabled.



Configuring jumbo frame support globally

The ServerIron ADX uses the largest MTU configured (IPv4 or IPv6) to calculate the maximum frame size programmed in hardware.

When a global IP MTU value is configured, it is applied to all physical ports that are part of the default VLAN and to all virtual (VE) interfaces that are associated with non-default VLANs. While the global IP MTU value supersedes the default MTU value for the ServerIron ADX, it does not supercede a value configured for an individual VE interface.

To configure an IPv4 MTU value globally, use the following command.

ServerIronADX(config)#ip global-mtu 9216

Syntax: [no] ip global-mtu ipv4 mtu-value

The ipv4-mtu-value variable can be from 576 to 9216. This variable specifies IP MTU value that will be applied globally. The sum of this value and 18 bytes (for the Layer-2 header) is used to set the maximum frame size at the port level. The default IP MTU value is 1500, which results in a default max frame size of 1518. Configuring an IP MTU value greater than 1798 enables jumbo frame support on the ServerIron ADX.

To configure an IPv6 MTU value globally, use the following command.

ServerIronADX(config)#ipv6 global-mtu 9216

Syntax: [no] ipv6 global-mtu ipv6-mtu-value

The ipv6-mtu-value variable can be from 1280 to 9216. The sum of this value and 18 bytes (for the Layer-2 header) is used to set the maximum frame size at the port level. The default IP MTU value is 1500, which results in a default max frame size of 1518.

Configuring jumbo frame support for a VE interface

Configuring an IP MTU value greater than 1798 on any virtual (VE) interface of the ServerIron ADX running router code enables jumbo frames.

The mtu-value variable specifies IP MTU value that will be applied for the specified VE interface. Values can be specified for both IPv4 and IPv6 traffic. The ServerIron ADX uses the largest IP MTU value configured (IPv4 or IPv6) to calculate the maximum frame size programmed in hardware.

To configure an IPv4 MTU value for a VE interface, use the following command.

ServerIronADX(config)#interface ve 3ServerIronADX(config-vif-3)#ip mtu 9216

Syntax: [no] ip mtu ipv4 mtu-value

For IPv4 traffic, the ipv4-mtu-value variable can be from 576 to 9216. The sum of this value and 18 bytes (for the Layer-2 header) will be used to set the maximum frame size at the port level. The default IP MTU value is 1500, which results in a default max frame size of 1518.

Use the following command to configure an IPv6 MTU value for a VE interface:

ServerIronADX(config)#interface ve 3ServerIronADX(config-vif-3)#ipv6 mtu 9216

Syntax: [no] ipv6 mtu ipv6-mtu-value



For IPv6 traffic, the ipv6-mtu-value variable can be from 1280 to 9216. The sum of the configured value and 18 bytes (for the Layer-2 header) defines the maximum frame size at the port level. The default IP MTU value is 1500, which results in a default max frame size of 1518.

An IP MTU value set with this command supersedes the default MTU value for the ServerIron ADX as well as any global level that is configured on the ServerIron ADX.

NOTEConfiguring an IP MTU value greater than 1798 on any virtual interface of the ServerIron ADX running router code enables jumbo frames.

Displaying the IP MTU value

The following commands allow you to view the currently configured IP MTU values on a ServerIron ADX. These values can be displayed for a physical Ethernet interface or for a virtual interface (VE) as shown.

To display the IP MTU value for a physical Ethernet interface use the command shown in the following. The MTU value is displayed as MTU 4000 bytes.

To display the IP MTU value for a virtual (VE) interface use the command shown in the following. The MTU value is displayed as MTU 7000 bytes.

Syntax: show interface [Ethernet portnum] [ve ve-num]

ServerIronADX(config)#show int e 1/1GigabitEthernet1/1 is down, line protocol is up Hardware is GigabitEthernet, address is 0004.08a0.4040 (bia 0004.08a0.4040) Configured speed auto, actual unknown, configured duplex fdx, actual unknown Member of L2 VLAN ID 1, port is untagged, port state is FORWARDING STP configured to ON, priority is level0, flow control enabled mirror disabled, monitor disabled Not member of any active trunks Not member of any configured trunks No port name MTU 4000 bytes, encapsulation ethernet IPv6 is disabled 300 second input rate: 0 bits/sec, 0 packets/sec, 0.00% utilization 300 second output rate: 0 bits/sec, 0 packets/sec, 0.00% utilization 0 packets input, 0 bytes, 0 no buffer Received 0 broadcasts, 0 multicasts, 0 unicasts 0 input errors, 0 CRC, 0 frame, 0 ignored 0 runts, 0 giants, DMA received 0 packets 0 packets output, 0 bytes, 0 underruns Transmitted 0 broadcasts, 0 multicasts, 0 unicasts 0 output errors, 0 collisions, DMA transmitted 0 packets

ServerIronADX(config-vif-6)#show interfaces ve 6Ve6 is down, line protocol is up Hardware is Virtual Ethernet, address is 0004.08a0.4040 (bia 0004.08a0.4040) No port name Internet address is 192.168.2.1/24, MTU 7000 bytes, encapsulation ethernet IPv6 is disabled



Limiting the maximum number of TCP SYN requestsYou can limit the maximum number of TCP SYN requests per second per server. A TCP SYN request is a packet a client sends requesting a TCP connection to the server.

To limit the connections to a maximum of 3500 for all Web servers on the network shown in Figure 5, enter the following command.

ServerIronADX(config)#server syn-limit 3500

Syntax: [no] server syn-limit number

The number is the maximum number of TCP SYN requests per second per server. Enter an integer from 1 to 65535. The default value is 65535.

Configuring the connection rateConnection Rate Control (CRC) specifies the maximum number of new TCP, UDP, or individual port connections per second allowed on the real server.

It enables you to limit the connection rate to a real server for the following:

• All TCP traffic

• All UDP traffic

• Individual TCP or UDP ports

The ServerIron ADX increments the connection counter for real server connections only after the ServerIron ADX selects a server for the connection. If the ServerIron ADX cannot serve a client request because a real server, cache, or firewall already has the maximum number of connections for the current second for the requested port, the ServerIron ADX tries another server. If there are no servers available, the ServerIron ADX sends a TCP RST to the client.

If you configure a limit for TCP or UDP and also for an individual application port, the ServerIron ADX uses the lower limit. For example, if you limit new TCP connections to a real server to 1000 per second and also limit new HTTP connections to 600 per second, the ServerIron ADX limits connections to TCP port HTTP to 600 per second.

NOTEThe ServerIron ADX counts only the new connections that remain in effect at the end of the one-second interval. If a connection is opened and terminated within the interval, the ServerIron ADX does not include the connection in the total for the server.

NOTEConnection rates might not be strictly limited to the configured values. A slight drift can be introduced due to latency. For example, with traffic running at 1000 connections per second, and the max-tcp-conn-rate command is configured at 100, the connection rate could go up to 140.

To limit the number of new TCP and UDP connections a real server can receive each second, enter commands such as the following.

ServerIronADX(config)#server real RS1 10.2.3.4ServerIronADX(config-rs-RS1)#max-tcp-conn-rate 1000ServerIronADX(config-rs-RS1)#max-udp-conn-rate 800

The first command limits new TCP connections to the real server to 1000 per second. The second command limits the rate of new UDP connections to the real server to 800 per second.



Syntax: max-tcp-conn-rate num

Syntax: max-udp-conn-rate num

The num variable specifies the maximum number of connections per second. There is no default. The maximum connection rate that can be configured is 4294967295.

To limit the rate of new connections for a specific application port, enter commands such as the following.

ServerIronADX(config-rs-RS1)#port httpServerIronADX(config-rs-RS1)#port http max-tcp-conn-rate 600

These commands add port HTTP (80) to the real server and limit the rate of new connections to the port to 600.

Syntax: port TCP/UDP-portnum max-tcp-conn-rate num

Syntax: port TCP/UDP-portnum max-udp-conn-rate num

The TCP/UDP-portnum variable specifies the application port.

The num variable specifies the maximum number of connections per second. The maximum connection rate that can be configured is 4294967295.

Configuring hardware forwarding of pass-through trafficThis feature enables the hardware forwarding of pass-through traffic (traffic not meant for Layer 4 processing) generated by a real server.

NOTEThis feature cannot be enabled for real servers that support complex protocols (FTP and streaming media ports bound). The reason is that these applications negotiate ports for the data channel, on the fly.

When Syn-Proxy is configured on the ServerIron ADX, it is applied to both pass-through and SLB traffic. The "Syn-Proxy for PassThrough Traffic" and "Hardware Forwarding of Real Server PassThrough Traffic" features are mutually exclusive. Therefore, you need to configure Syn-Proxy only for SLB traffic when the hardware forward feature is enabled. Syn-Proxy for SLB traffic can be configured using the server security-on-vip-only command.

Hardware forwarding of pass through traffic is enabled under a real server. When you want non-SLB traffic from a particular real server to be hardware forwarded, enable hardware forwarding for that real server.

To configure hardware forwarding of pass-through traffic for a specific real server, enter the following command.

ServerIronADX(config-rs-rs1)#hw-fwd-pass-through-traffic

Syntax: [no] hw-fwd-pass-through-traffic



To globally configure hardware forwarding of pass-through traffic for all real servers in the system, enter the following command.

ServerIronADX(config)#server hw-fwd-pass-through-traffic

Syntax: [no] server hw-fwd-pass-through-traffic

The show cam layer4/7 command has been enhanced to show the new user type, Real server port..

Syntax: show cam layer4/7

Disabling port translationBy default, the ServerIron ADX translates the application port number requested by the client into the application port number you specify on the virtual server when you bind it to the real server. For example, if you bind port 80 on a virtual server to port 8080 on a real server, the ServerIron ADX translates the application port in the client’s request from port 80 into 8080 before forwarding the request to a real server.

A few ServerIron ADX configurations require that you disable translation for an application port. For example, if you want to bind multiple virtual IP addresses to the same real server, you must disable port translation for all but one of the virtual IP addresses, then bind the virtual IP addresses to an alias port for the application. Disabling port translation enables the virtual IP addresses to use the same actual port number on the real server while the ServerIron ADX collects and displays separate statistics for the alias port number associated with each virtual IP address.

For a complete configuration example, refer to “Multiple port binding using port aliases” on page 530.

To disable translation for an application port, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip v1 10.157.22.1ServerIronADX(config-vs-v1)#no port 80 translate

Syntax: [no] port tcp/udp-port translate

ServerIronADX#show cam layer4/7 detail slbUser Type: Real server port Entry Type: Real server portMatch Srcip: 10.32.5.111 (0x0a20056f) Mask: 0xffffffff Srcport : 5050 Mask: 0xffff16594 - (DestIP & 0xF): 0 to 1 FID: dd03 BP: 3/116596 - (DestIP & 0xF): 2 FID: dd02 BP: 3/116598 - (DestIP & 0xF): 3 FID: dd06 BP: 3/216598 - (DestIP & 0xF): 3 FID: dd06 BP: 3/216602 - (DestIP & 0xF): 6 to 7 FID: dd0b BP: 3/316604 - (DestIP & 0xF): 8 FID: dd0a BP: 3/316606 - (DestIP & 0xF): 9 FID: dd02 BP: 3/116608 - (DestIP & 0xF): a to b FID: dd03 BP: 3/116610 - (DestIP & 0xF): c FID: dd07 BP: 3/216612 - (DestIP & 0xF): d FID: dd06 BP: 3/216614 - (DestIP & 0xF): e FID: dd0b BP: 3/316616 - (DestIP & 0xF): f FID: dd0a BP: 3/3



Traffic distribution among BPsThe ServerIron ADX uses a hash algorithm to distribute traffic among barrel processors (BP). A default algorithm and 3 optional algorithms operate on the Source or Destination IP addresses to balance traffic among the BPs.

The default hash algorithm is “hash-crc32l”. In most situations, this setting will provide the most effective distribution of traffic across BPs. If you find however that traffic is not being efficiently distributed across the BPs on your ServerIron switch, you can try one of the other options.

To change the server hash algorithm from the default “hash-crc32l” to “hash-crc32u” use the following command.

ServerIronADX(config)#server hash-crc32u

Syntax: server [hash-crc32l | hash-crc32u | hash-xori | hash-xoru]

hash-crc32l: This algorithm performs CRC on the 32-bits of source IP in the forward direction and the 32-bits of Destination IP in the reverse direction. The lower five bits of the computed result are used to distribute traffic among BPs. This is the default setting.

hash-crc32u: This algorithm performs CRC on the 32-bits of source IP in the forward direction and the 32-bits of Destination IP in the reverse direction. The upper five bits of the computed result are used to distribute traffic among BPs.

hash-xorl: This algorithm performs XOR on the 32-bits of source IP in the forward direction and the 32-bits of Destination IP in the reverse direction. The lower five bits of the computed result are used to distribute traffic among BPs.

hash-xoru: This algorithm performs XOR on the 32-bits of source IP in the forward direction and the 32-bits of Destination IP in the reverse direction. The upper five bits of the computed result are used to distribute traffic among BPs.

Including the server client port in hash calculationsWhen there are a small number of client IP addresses that connect to a ServerIron ADX switch, the traffic distribution of IP addresses to the BPs might not be optimal. Where this is the case, it can be useful to include the client source port in the hash calculations. This configuration is achieved by running the following command.

ServerIronADX(config)#server source-port-hash

Syntax: [no] server source-port-hash

NOTEThis command can be configured with any of the hash algorithms configured using the server hash-xxx command described previously. This command cannot be used for protocols that involve dynamic ports such as FTP and RTSP and with sticky features.



Sending ICMP Port Unreachable or Destination Unreachable messages

NOTEICMP messages are disabled by default.

By default, if the ServerIron ADX receives a client request for a specific VIP and UDP port, but the requested port is not bound to the requested VIP, the ServerIron ADX drops the packet. For example, if a client sends a request to VIP 10.10.5.1 and UDP port 99, but configuration for VIP 10.10.5.1 on the ServerIron ADX does not include a binding for port 99, the ServerIron ADX drops the request without sending a message to the client.

You can configure the ServerIron ADX to send an “ICMP Port Unreachable message” instead of dropping the packet without notice.

Also by default, if a client requests an unavailable TCP or UDP port, the ServerIron ADX does not send an “ICMP Destination Unreachable message” to the client.

For HTTP traffic, you can configure the ServerIron ADX to send such a message to the client, if the requested port either is not configured on any of the real servers or is unavailable because all the servers configured with the requested port are busy or down.

To configure the ServerIron ADX to send “ICMP Destination Unreachable messages” to clients, or to send an “ICMP Port Unreachable message” when the device receives a request for a UDP port that is not bound to the requested VIP, enter the following command.

ServerIronADX(config)#server icmp-message

Syntax: [no] server icmp-message

NOTEIf the server disable-ping-vip-down command is configured, the ServerIron ADX will stop responding to ICMP echo request when the VIP is down.

Sending a TCP RST to a client that requests unavailable applicationsIf a client requests an unavailable application, the ServerIron ADX does one of the following:

• Quietly drops the request.

• Sends an ICMP Destination Unreachable message (for UDP or TCP).

• Sends a TCP RST (for TCP only) – the default action.

Generally, an application is unavailable if all the real servers that have the application are unavailable or if the application is not configured on the VIP requested by the client.

To configure the ServerIron ADX to send a TCP RST to a client, enter the following command.

ServerIronADX(config)#server reset-message

Syntax: [no] server reset-message



NOTEThe server reset message overrides the ICMP Destination Unreachable message. If the configuration contains both, the ServerIron ADX sends a TCP RST instead of an ICMP message for TCP requests. For UDP requests, the device still sends ICMP messages. TCP RST does not apply to UDP.

For information on how to globally configure the ServerIron ADX to send an ICMP Destination Unreachable message to a client, refer to “Sending ICMP Port Unreachable or Destination Unreachable messages” on page 150.

NOTEThe server no-reset-on-max-conn command overrides the server reset-message command. For more information, refer to “Disabling TCP RST message on maximum connections” on page 152.

Sending a TCP RST when TCP session entry ages outBy default, the ServerIron ADX does not send a TCP RST to a client or server when its TCP session in the session table ages out.

You can enable the ServerIron ADX to send a TCP RST to a client or server when a TCP session entry in use by the client or server ages out. To do this, enter the following command.

ServerIronADX(config)#server tcp-age reset

Syntax: [no] server tcp-age reset [both | client | server]

This command only works if you are running Layer 7 SLB.

The both option (default) enables the device to send messages to clients and servers.

The client option enables the device to send messages only to clients.

The server option enables the device to send messages only to servers.

Disabling TCP RST message when a real server goes down during an open sessionBy default, if a real server goes down during an open TCP session with a client, the ServerIron ADX sends a TCP RST message to the client to terminate the session normally. When the real server comes back up, clients can establish a new session with the server.

You can globally disable the TCP RST message from being sent under these circumstances. When you disable the TCP RST message, the client can resume the interrupted session when the real server comes back up.

NOTEDisabling the TCP RST messages affects only the message sent to a client when a real server goes down during a client’s session with the server. TCP RST messages sent under other circumstances are not affected.

To globally disable the TCP RST message from being sent, enter the following command.

ServerIronADX(config)#server no-reset-for-established-session

Syntax: [no] server no-reset-for-established-session



By default, sending TCP RST messages is enabled.

Disabling TCP RST message on maximum connectionsWhen a client sends a TCP SYN to a VIP, the ServerIron ADX selects one of the real servers bound to the VIP for the client's connection. If the ServerIron ADX cannot select a real server (for example, if the server port is down, or the server port has reached its maximum connection limit), then by default the ServerIron ADX sends a TCP RST to the client.

You can configure the ServerIron ADX not to send a TCP reset when the maximum connections limit is reached. The client can then subsequently attempt to establish a connection, by which time a real server might have fewer connections that its maximum connections limit, and the ServerIron ADX would be able to select it.

To disable the TCP RST message sent when the maximum connections limit on the real servers is reached, enter the following command.

ServerIronADX(config)#server no-reset-on-max-conn

Syntax: [no] server no-reset-on-max-conn

NOTEThis command overrides the server reset-message command, which enables the ServerIron ADX to send TCP RST to clients that request unavailable applications. If the configuration contains both commands, the ServerIron ADX will not send a TCP RST to a connecting client if the maximum connections limit on the real servers has been reached.

Decrement counters in deletion queueOn a ServerIron ADX, when a connection is closed, the corresponding sessions are not immediately deleted. The sessions are put in a deletion queue and deleted later at MSL time (default is 8 seconds). Statistics on the closed connections are not adjusted until the sessions are actually deleted from the deletion queue.

To adjust statistics when sessions are put in the deletion queue, use the following command.

ServerIronADX(config)#server decrement-counter-when-put-in-delQ

Syntax: [no] server decrement-counter-when-put-in-delQ

Optimized fast-path SLB processingYou can enable the ServerIron ADX to use fast-path processing for stateful or stateless SLB:

• Stateful SLB is the standard form of SLB that uses session table entries to track session information. All traffic for stateful SLB takes an optimized processing path.

• Stateless SLB is a form of SLB that does not use session table entries. All packets that go through stateless ports take an optimized processing path.

When you enable fast-path processing, the ServerIron ADX does not process every TCP or UDP packet in a given session in detail. Instead, the ServerIron ADX uses information gathered during setup of the session to forward packets in the session.



NOTESLB optimization is useful if simple SLB (stateful or stateless) is the primary or sole application on the device. If you use the ServerIron ADX for other features such as global server load balancing (GSLB) or Firewall Load Balancing (FWLB), SLB optimization is not useful.

NOTEStateful and stateless SLB traffic is optimized by default.

Enabling fast-path processing for stateless SLB

When you enable fast-path processing, the ServerIron ADX does not process every TCP or UDP packet in a given session in detail. Instead, the ServerIron ADX uses information gathered during setup of the session to forward packets in the session. All packets that go through stateless ports take an optimized processing path.

SLB optimization is useful if simple SLB is the primary or sole application on the device. If you use the ServerIron ADX for other features such as GSLB or FWLB, SLB optimization is not useful. Fast-path processing applies only to some configurations.

To enable fast-path processing for stateless SLB, enter the following command.

ServerIronADX(config)#server fast-stateless

Syntax: [no] server fast-stateless

Configuration considerations

Consider the following:

• You can use only one type of optimization at a time. You cannot use stateful and stateless optimization at the same time.

• Optimization applies only to SLB TCP or UDP traffic that is initiated by clients. Other types of traffic are not optimized.

• Optimization does not apply to fragmented IP packets.

• In the current release, the port name or number on the VIP must be same as the one on the real server bound to the VIP. Port translation is not supported.

• FTP traffic is not supported.

• Source NAT (source-nat command) is not supported.

• Host ranges (host-range command) are not supported.

• The show server stateless command does not display hits.

• Many-to-one TCP or UDP port binding (no port tcp/udp-port translate command) is not supported.

NOTETraffic for an SLB configuration that does not meet these criteria is still forwarded using normal processing, but fast-path processing is not used.



• For stateless SLB, optimization is supported only for the following TCP or UDP ports that are well-known to the ServerIron ADX:

- 7 (echo)

- 9 (discard)

- 21 (ftp)

- 22 (ssh)

- 23 (telnet)

- 25 (smtp)

- 37 (time)

- 49 (tacacs)

- 53 (dns)

- 67 (bootps)

- 68 (bootpc)

- 69 (tftp)

- 80 (http)

- 109 (pop2)

- 110 (110)

- 119 (nntp)

- 123 (ntp)

- 137 (netbios-ns)

- 138 (netbios-dgm)

- 143 (imap4)

- 161 (snmp)

- 162 (snmp-trap)

- 179 (bgp)

- 195 (dnsix)

- 389 (ldap)

- 434 (mobile-ip)

- 443 (ssl)

- 517 (talk)

- 520 (rip)

- 554 (rtsp)

- 1755 (mms)

- 1812 (radius)

- 1645 (radius-old)

- 7070 (pnm)

- 1558 (xing)

- 12468 (vxstream1)

- 12469 (vxstream2)



Configuring TCP fast agingFollowing a RST from the server, the ServerIron ADX ages out session table entries in the amount of time specified in the server msl command, by default 8 seconds. You can optionally configure the ServerIron ADX to use the 1- to 2- minute aging time used in previous releases.

To set the amount of time a session table entry stays in the delete queue following a RST from the server, enter a command such as the following.

ServerIronADX(config)#server msl 2

Syntax: server msl seconds

The seconds variable can be from 1 through 180 seconds. The default is 8 seconds. Note that attempting to set the value to 0 resets the value to the default (8 sec.).

To disable TCP fast aging and use the 1- to 2- minute aging time from previous releases, enter the following command.

ServerIronADX(config)#server no-tcp-fast-age-on-server-reset

Syntax: [no] server no-tcp-fast-age-on-server-reset

Server opt-enable-route recalculationFor optimized SLB, the ServerIron ADX does not calculate a reverse route for every packet in a flow. In this scenario, the ServerIron ADX uses the route that it learns in the first reverse packet, such as SYN-ACK packet. However, this calculation might not be desirable in a environment where a route can be dynamically changed, such as a case with upstream firewall failover, where the new firewall has the same IP address but a different MAC address. To cover these cases, the server opt-enable-route-recalculation command is used to force the ServerIron ADX to dynamically calculate the reverse route.

In the case where the Server ADX only has Layer 4 SLB functionality, it will select an optimized way to accelerate the session handling by creating data sessions and remaining with the same ports for forwarding and reverse data traffic when the ServerIron ADX receives the SYN packet. If later on, traffic needs to go through different ports, the traffic will fail. The server opt-enable-route-recalculation command is used to solve this problem by routing data out of the ports after recalculating the route. By enabling this command, however, the network performance will be affected.

NOTEThis command should be used only when there is a need to recalculate reverse route. Most situations do not require this.



Enabling use of the client MAC addressBy default, the ServerIron ADX uses the MAC address of its default gateway as the destination MAC address for server replies (TCP SYN and TCP SYN ACK) to a client. This default works well in some configurations but can cause difficulties in configurations where there are multiple VLANs and multiple instances of VRRP running in each VLAN on upstream routers.

You can enable use of the client MAC address instead of the default gateway address, by entering the following command.

ServerIronADX(config)#server l7-dont-use-gateway-mac

Syntax: [no] server l7-dont-use-gateway-mac

Enabling transparent VIPTransparent VIP allows you to configure a ServerIron ADX to transparently load balance a VIP, without owning the VIP address. Multiple ServerIron ADXs on which this virtual server is configured to be transparent can load balance requests for the server. For examples and configuration information, refer to Chapter 3, “Stateless Server Load Balancing”.

To configure an individual virtual server for the transparent VIP feature, enter a command such as the following.

ServerIronADX(config-vs-TransVIP)#transparent-vip

Syntax: [no] transparent-vip

Enabling SYN ACK threshold The SYN ACK threshold specifies the number of contiguous unacknowledged TCP SYN ACKs the ServerIron ADX allows to accumulate for a real server, before determining that the server is down and marking it FAILED. For examples and configuration information, refer to “Reassign threshold” on page 279.

Syntax: server reassign-threshold number

The number variable is the threshold. Enter a number from 6 to 4000. If you do not specify a number, the ServerIron ADX assigns a threshold value of 20.

Replacing the source MAC address of the packetWhen you configure the server source-mac-replacement command, if the incoming and outgoing SLB traffic belongs to different VLANs, the source MAC address of the packet will be replaced using the ServerIron ADX MAC address.

ServerIronADX(config)#server source-mac-replacement

Syntax: [no] server source-mac-replacement



Cloning real serversTo simplify configuration for large server farms, you can clone real servers. When you clone a real server, you make a copy of the real server’s configuration information under a new name. The copy includes the port bindings to the virtual server.

To clone a real server, enter commands such as the following.

ServerIronADX(config)#server real rs1 10.2.3.4 ServerIronADX(config-rs-rs1)#clone-server rs2 10.6.7.8

The first command changes the CLI to the configuration level for the real server you want to copy. The second command creates a clone of real server rs1. The clone is named "rs2" and has IP address 10.6.7.8.

Syntax: [no] clone-server name ip-addr

• The name variable specifies the name of the clone.

• The ip-addr variable specifies the IP address of the clone.

NOTETo delete a server clone, you must manually edit the startup-config file to remove the command. The "no" option is not supported for this command.

Configuring a host rangeIf you want to use the Unlimited VIP feature to load balance a large set of contiguous IP addresses on the real server, configure a host range to create a range of contiguous virtual IP addresses (VIPs) based on the VIP address of the virtual server. The ServerIron ADX creates the range by creating the number of VIPs that you specify with this command. You do not specify a range; you specify the number of hosts in the range. The beginning address in the range is always the VIP. The IP addresses must be contiguous on the real server.

To define a range of 500 contiguous VIPs, enter commands such as the following.

ServerIronADX(config)#server real-name r1 10.4.4.4ServerIronADX(config-rs-r1)#host-range 500ServerIronADX(config-rs-r1)#exitServerIronADX(config)#server real-name r2 10.4.4.5ServerIronADX(config-rs-r2)#host-range 500ServerIronADX(config-rs-r2)#exitServerIronADX(config)#server virtual-name-or-ip lotsofhosts 10.157.22.99ServerIronADX(config-vs-lotsofhosts)#host-range 500ServerIronADX(config-vs-lotsofhosts)#exit

Defining a host range simplifies configuration by allowing you to enter a single command or Web option for the whole range of addresses instead of entering information for each address individually.

You must also configure a corresponding range of addresses on the virtual server. For a complete configuration example, refer to “TCP/UDP application groups” on page 531.

To configure a host range on a real server.

ServerIronADX(config)#server real-name r1 10.0.0.1ServerIronADX(config-rs-r1)#host-range 20

This command configures a range of 20 IP addresses, from 10.0.0.1 through 10.0.0.20.



Syntax: [no] host-range num

Configuring IPv6 host-range

The host-range capability enables the administrator to define a range of servers having contiguous IPv6 addresses.

NOTEWhile binding host-range between virtual servers and real servers, one must use identical host-range size.

NOTEBinding of a virtual server having host-range with a real server without having host-range is permitted.

To configure host-range for both Virtual and Real IPv6 servers, use the following commands.

ADX 1000(config)#server real v6_real 2001:DB8::345:250ADX 1000(config-rs-v6_real)#host-range 4ADX 1000(config-rs-v6_real)#port httpADX 1000(config-rs-v6_real)#exit

ADX 1000(config)#server virtual v6_virtual 2001:DB8::345:1000ADX 1000(config-vs-v6_virtual)#host-range 4ADX 1000(config-vs-v6_virtual)#port httpADX 1000(config-vs-v6_virtual)#bind http v6_real http

Syntax: [no] host-range num

The num variable identifies the host-range. The value ranges from 1 through 4096 for both real and virtual servers.

NOTEThe IPv6 host-range may not be combined with features such as stateless SLB, IPv6 translation (SLB664 and SLB446), TCP Syn-Proxy and VIP protection.

Unbinding all application ports from virtual serversBy default, a real server’s application ports remain bound to the virtual servers to which you bind them. You can unbind all of a real server’s application ports from the virtual servers.

To unbind a real server’s application ports, enter the following command at the configuration level for the server.

ServerIronADX(config-rs-R1)#port unbind-all

Syntax: port unbind-all

NOTEOnce you unbind the ports, you can rebind them only on an individual virtual server and port basis.



Identifying VIP port as TCP only or UDP only You can explicitly identify an application port to be "TCP only" or "UDP only". The "TCP only" port accepts connections that arrive on TCP transport and drops connections that arrive on UDP transport. The ports that are identified as "UDP only" ports accept connections only on UDP transport:

• Allow "TCP only" or "UDP only" port definitions under virtual server

• Allow similar definitions under real server also

On ServerIron ADX, when a port is defined under VIP, both UDP and TCP traffic with the port number are enabled and passed through to the real server. This scenario is not desirable in some cases.

As an enhancement, the user is allowed to define a TCP-only or UDP-only port so that only TCP or UDP traffic with the specified port number can pass through. TCP-only or UDP-only traffic control has been supported internally on ServerIron ADX, but no CLI is available for the user to enable it.

As the enhancement, the following commands allow the user to enable or disable TCP-only or UDP-only traffic control for a port defined under VIP.

Syntax: [no] port port tcp-only

Syntax: [no] port port udp-only

The command is available under VIP configuration mode.

When either TCP-only or UDP-only is configured, only TCP traffic or UDP traffic can pass through as configured; otherwise both TCP traffic and UDP traffic can pass through. TCP-only and UDP-only are exclusive, which means when TCP-only is configured, TCP-only and UDP-only cannot be configured for a particular port at the same time. UDP-only will be automatically disabled if TCP-only is configured, and vice versa.

Enabling fast aging for UDP sessionsWhen fast aging for UDP sessions is configured, a client request causes the ServerIron ADX to add an entry to its session table; when a response is detected, the ServerIron ADX immediately deletes the session table entry.

NOTEFast aging is the default behavior for the well-known DNS and RADIUS ports. To change DNS or RADIUS to use the UDP age timer instead, refer to “Enabling normal UDP aging for DNS and RADIUS” on page 160.

When this feature is configured, if the ServerIron ADX detects a server response to a client request, and the response is not fragmented, the session table entry is deleted immediately. If the response is fragmented, the ServerIron ADX waits for the last fragment to arrive, forwards it to the client, and then sends the session to the delete queue. By default, the session stays in the delete queue for 8 seconds before being deleted. You can change the amount of time the session stays in the delete queue to between 1 and 40 seconds.

To activate fast aging for UDP sessions for port 1234, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip vs1 192.168.1.2ServerIronADX(config-vs-vs1)#port 1234 udp-fast-age

Syntax: port UDP-portnum udp-fast-age



To set the amount of time sessions for ports configured with the udp-fast-age keyword that stays in the delete queue before being deleted, enter the following command.

ServerIronADX(config)#server msl 2

Syntax: server msl secs

The secs variable can be from 1–40 seconds.

Enabling normal UDP aging for DNS and RADIUSBy default, the ServerIron ADX immediately deletes a UDP DNS or RADIUS session table entry when the ServerIron ADX receives a reply for the application from a real server. You can configure the ServerIron ADX to instead age out DNS or RADIUS sessions normally using the UDP age timer.

To age DNS or RADIUS sessions using the UDP age timer, enter the following command at the global CONFIG level of the CLI.

ServerIronADX(config-vs-VIP1)#port dns udp-normal-age

Syntax: [no] port dns | radius udp-normal-age

For DNS and RADIUS UDP load balancing, unless the port is configured with this command, the DNS or RADIUS sessions are always aged out after two minutes.

NOTEBy default, a ServerIron ADX will exercise normal-age for DNS and RADIUS if the response is fragmented traffic from a real server. If you would like to enable the fast-age feature for fragmented traffic as well as non-fragmented traffic, you need to explicitly configure the udp-fast-age keyword on the port level.

Setting TCP and UDP ages for VIPsThe TCP and UDP ages specify how many minutes a TCP or UDP session can remain inactive before the ServerIron ADX closes the session and clears the session from its session table. You can set the TCP or UDP ages for a specific virtual server, and you can set the TCP or UDP ages for an individual port on a virtual server.

NOTEThe session age is per minute and has a one minute range. For example, if you configured a TCP or UDP age of three minutes for a virtual server, the age timeout is from two to three minutes.

For example, to set the TCP age for virtual server v1 to 20 minutes, enter the following commands.

ServerIronADX(config)#server virtual-name-or-ip v1ServerIronADX(config-vs-v1)#tcp-age 20

Syntax: [no] tcp-age minutes

To set the UDP age for virtual server v1 to 26 minutes, enter the following commands.

ServerIronADX(config)#server virtual-name-or-ip v1ServerIronADX(config-vs-v1)#udp-age 26

Syntax: [no] udp-age minutes



To set the TCP age for the HTTP port on virtual server v1 to 10 minutes, enter the following commands.

ServerIronADX(config)#server virtual-name-or-ip v1ServerIronADX(config-vs-v1)#port http tcp-age 10

Syntax: [no] port port tcp-age minutes

To set the UDP age for the SNMP port on virtual server v1 to 26 minutes, enter the following commands.

ServerIronADX(config)#server virtual-name-or-ip v1ServerIronADX(config-vs-v1)#port snmp udp-age 26

Syntax: [no] port port udp-age minutes

You can set the TCP or UDP age from 2 through 60 minutes. The default TCP age is 30 minutes. The default UDP age is five minutes.

More specific settings override more general settings; that is, a TCP or UDP age setting for the HTTP port will override a TCP or UDP age setting for the virtual server, which will override the global TCP or UDP age (set with the server tcp-age or server udp-age commands).

Configuring session aging behaviorIn stateful (default) mode, sessions are created when traffic flows through the ServerIron ADX. Two sessions are created for each flow: “foreward” session (In Layer4 SLB, Client to VIP), and “reverse” session (In Layer4 SLB, Real-Server to Client). These two sessions are tied together. Each session has an associated time after which the session is marked for removal. The session age is refreshed each time there is a new packet on the flow. The default mechanism to delete sessions is when both forward and reverse sessions reach their age limit.

You can use the following commands to change the default session aging behavior.

To age out forward and reverse sessions independently use the following command,

ServerIronADX(config)#server one-way-session-age

Syntax: server one-way-session-age

If one session ages out, delete that session but do not delete the other session.

To delete both sessions when any of the sessions ages out use the following command.

ServerIronADX(config)#two-way-session-age-on-one-age

Syntax: server two-way-session-age-on-one-age

Configuring DNS CPU-based throttlingDNS request processing time can become very slow when CPU utilization is at a high level (90 - 95%). With this feature you can direct a ServerIron ADX to reject new DNS UDP and TCP SSL requests when CPU utilization goes beyond a configured threshold.

You can set CPU-based throttling for DNS UDP and TCP SSL traffic as shown.

ServerIronADX(config)#server throttle-on-overload 40

Syntax: [no] server throttle-on-overload cpu-percentage



The cpu-percentage specifies the threshold of CPU utilization when the ServerIron ADX will reject new DNS UDP and TCP SSL requests.

NOTECPU utilization is not collected for every packet but every second. Consequently, the throttling decision might not always be accurate. Because of this, CPU utilization might go higher than the set threshold in some situations.

Configuring UDP DNS count connectionWhen a client’s UDP DNS traffic follows a pattern such that the 4 tuples (Source IP, Destination IP, Source Port, Dest Port) are exactly the same across multiple DNS requests, the ServerIron ADX will have an issue. This is because the 5 tuples (SIP, DIP, SP. DP and protocol) based on which a new session is created by the ServerIron ADX is no longer unique for the subsequent connections but will match the existing connection created by the first DNS request. When the first response is received from the real server, the session which was used by the multiple DNS connections will be deleted as expected. This leads to the subsequent response from the real server to not find a session and therefore will get the Layer 2 information forwarded instead of the translation from real server to the virtual IP (VIP). This will result in DNS responses reaching the client un-translated.

To resolve this, configure the ServerIron ADX to keep a count of the number of UDP DNS connections used by the session and to delete the session only when all the responses to this session is received. Use the command at the global config level as shown.

ServerIronADX(config)#server dns-udp-count-connection

Syntax: [no] server dns-udp-count-connection

Maximum server, port, and health check countTable 10 and Table 11 shows the minimum, maximum and default number of supported real servers, virtual servers and ports on the ServerIron system.

NOTEThe maximum number of ports with L47 health checks enabled might be lower.

TABLE 10 Number of supported real servers, virtual servers, and ports on a ServerIron ADX4000, ServerIron ADX8000 and ServerIron ADX10000

Port type Default Minimum Maximum

Real Server 4096 64 16384

Virtual Server 1024 64 4096

Server Ports 8192 256 32768

TABLE 11 Number of supported real servers, virtual servers, and ports on a ServerIron ADX1000


Real Server 1024 64 4096



NOTEThe implicit default port under virtual and real servers are included in the port count.

Policy-based routing for reverse SLB trafficPolicy-based routing (PBR) is supported for reverse SLB traffic on the ServerIron ADX. Policy-based routing routes traffic based on policies you define. A PBR policy specifies the next hop for traffic that matches the policy.

To configure PBR, define the policies using IP ACLs and route maps, then enable PBR globally or on individual interfaces. The device routes traffic that matches the ACLs, according to the instructions in the route maps.

In a network where clients belonging to different subnet and VLANs are sending traffic to VIPs belonging to their respective subnet, you can configure PBR to send return traffic back to each client the way it came, rather than having all the traffic use the default route. To do this, you can configure ACLs and route maps and apply them either globally or to individual interfaces.

In the following example below, clients belonging to subnets 172.16.0.0/16 and 172.17.0.0/16 are accessing VIP 192.168.10.1 via Router B, while all other clients access the VIP via Router A. The next-hop router for 172.16.0.0/16 and 172.17.0.0/16 is 192.168.2.254, while the default route is used for all other clients.

Virtual Server 256 64 1024

Server Ports 2048 256 8192

TABLE 11 Number of supported real servers, virtual servers, and ports on a ServerIron ADX1000 (Continued)




To redirect the return traffic to some specified clients, you can configure the ACL and route map in either of the following ways:

1. Specify clients subnet address as the destination address in the ACL statement.

ServerIronADX(config)#access-list 101 permit ip any 172.16.0.0 0.0.255.255ServerIronADX(config)#access-list 101 permit ip any 172.17.0.0 0.0.255.255ServerIronADX(config)#route-map test-route permit 10ServerIronADX(config-route-map test-route)#match ip address 101ServerIronADX(config-route-map test-route)#set ip next-hop 192.168.2.254ServerIronADX(config-route-map test-route)#exitServerIronADX(config)#ip policy route-map test-route

2. Specify VIP host IP address (or IP address range that the VIP belongs) as the source IP address in the ACL statement.

ServerIronADX(config)#access-list 101 permit ip host 172.168.10.1 anyServerIronADX(config)#route-map test-route permit 10ServerIronADX(config-route-map test-route)#match ip address 101ServerIronADX(config-route-map test-route)#set ip next-hop 192.168.2.254ServerIronADX(config-route-map test-route)#exitServerIronADX(config)#ip policy route-map test-route

Policy-Based Routing (PBR) is handled by Application Cores (also called “Barrel Processors” or BPs), hence PBR can only normally operate on traffic defined within a “server” function.

In cases where PBR is necessary for non-SLB IP traffic, there are two options available. Use one of these options and then apply PBR policies normally:

1. Define real server or remote server with the IP addresses in question, so that reverse traffic will be forwarded to the BPs. Thus the CAM entries for these real/remote entries will forward traffic to the BPs for processing.

2. Configure “server cpu-forward” globally so that all traffic will be forwarded to the BP. A “catch-all CAM entry (similar to that used by FWLB) will be created to force all traffic through the BPs.

Dedicated next hop per VIP for reverse SLB trafficThis feature allows you to configure a default gateway for reverse SLB traffic at the Virtual server level. It is provided as a less cumbersome alternative to the procedure described in “Policy-based routing for reverse SLB traffic” on page 163. This feature is only available for a ServerIron ADX running router code.

To configure a virtual server with a next hop gateway use the command shown in the following.

ServerIronADX(config)#server virtual-name-or-ip v1 10.1.1.1ServerIronADX(config-vs-v1)#next-hop 10.1.1.100

Syntax: [no] next-hop next-hop-IPaddress

The next-hop-IPaddress variable specifies the IP address of the nest hop gateway for the virtual server.

NOTEThe IP address specified for the next-hop-IPaddress must be directly connected to the ServerIron ADX.



You can also configure the virtual server to allow it to fall back to its default gateway as shown in the following.

ServerIronADX(config)#server virtual-name-or-ip v1 10.1.1.1ServerIronADX(config-vs-v1)#next-hop-allow-fallback-to-default-gateway

Syntax: [no] next-hop-allow-fallback-to-default-gateway

Dynamic NAT for real servers using virtual server addressA ServerIron ADX can use a virtual server address as a dynamic NAT address for real servers. This feature enables the use of virtual server IP addresses for outbound connections from real servers.

VIP route health injectionVIP route health injection (RHI) allows the ServerIron ADX to advertise the availability of an IPv4 or IPv6 VIP address (instead of a real host) throughout the network. Multiple ServerIrons with identical VIP addresses and services can exist throughout the network. This feature allows the ServerIron ADX VIP to be used in lieu of the same VIP on other ServerIrons if the VIP is no longer healthy on those devices. A VIP can also provide the services because it is logically closer to the client systems than the other ServerIrons.

Specifically, you can configure a ServerIron ADX to check the health of a VIP configured on it and inject a VIP route into the network to force a preferred route to the VIP. VIP RHI checks the VIP health and reports one of the following:

• VIP is healthy. If the VIP is healthy, the ServerIron ADX injects a VIP route into its route table for the VIP. The ServerIron ADX then advertises the route to other routers using an IGP routing protocol, such as OSPF or OSFPv3.

• VIP is not healthy. The ServerIron ADX removes the IP route to the VIP from its route table. As a result, the route is withdrawn by the routing protocols and is no longer used by upstream routers. The upstream routers instead use another route to the same VIP.

NOTEIPv4 uses the OSPF routing protocol. For IPV6, the OSPFv3 routing protocol is used.

Routers receiving client traffic for the VIP select the best route to the VIP. As a result, clients enjoy fast response time regardless of their location, because their gateway routers use the best path to the VIP. RHI also prevents client traffic from being routed to a VIP that is unavailable.

VIP route health injection advertises the host route to the VIP instead of a network route to the VIP's subnet. This approach ensures that the clients' gateway routers receive a route to the IP address only if that VIP is available.

Configuration of VIP RHI is the same in most cases for IPv4 and IPv6 addresses. It is clearly shown in the following sections where there are differences in configuration commands or procedures.

NOTEDisabling the real ports of all real servers using the server disable-all-real command causes the respective virtual port's RHI state to become "Not Healthy", and the VIP host route will not be advertised. In contrast, when you disable the virtual port of virtual server, the RHI state of a virtual port will not become "Not Healthy", and the ServerIron ADX will keep advertising the VIP host route.



Injecting and deleting VIP route based on VIP health

The route for a VIP is injected when the VIP was previously unhealthy and is now deemed to be healthy. Similarly, the route for the VIP is withdrawn if it was previously healthy and is now down.

The health of a VIP is based on the health of its VIP ports. The health of a VIP port is based on the health of the real server ports bound to that VIP port.

You can configure any of the traditional health checks supported for the real servers. When a real server port fails the health check, the ServerIron ADX will check if the real server port is bound to a VIP port whose VIP has the RHI feature enabled. If so, the ServerIron ADX will determine how many real server ports bound to the VIP port are healthy. If the amount is below the threshold (if percentage threshold is configured) or if none of the other real server ports are healthy (if percentage threshold is not configured), then the VIP port will be declared unhealthy. If you have configured the option where a VIP should be considered healthy if at least one VIP port is healthy, then the ServerIron ADX will check if there are any other healthy VIP ports. If there are none, it will delete the VIP route. If you have not configured this option (a VIP should be considered healthy only if all VIP ports are healthy), then the ServerIron ADX will delete the VIP route.

Similarly, when a real server port transitions from the failed to the active state, the ServerIron ADX will check if the real server port is bound to a VIP port whose VIP has the RHI feature enabled. If this is the case, the ServerIron ADX will determine how many real server ports bound to the VIP port are healthy. If you have configured a percentage threshold, and if this number is above the threshold, then ServerIron ADX will declare this VIP port healthy. If you have not configured a threshold, then the ServerIron ADX will declare this VIP healthy. If you have configured the option where a VIP should be considered healthy if at least one VIP port is healthy and the VIP was previously unhealthy, then it will inject the VIP route. If you have not configured this option (a VIP should be considered healthy only if all VIP ports are healthy), then the ServerIron ADX will check if all other VIP ports are healthy. If they are, the ServerIron ADX will inject the VIP route.

Configuration considerations

Before you enable RHI, consider the following three issues:

• Static route redistribution — It is required to redistribute the host route for the VIP into OSPF or OSPFv3. To enable redistribution of static routes for IPv4, enter commands such as the following:

ServerIronADX(config)#router ospfServerIronADX(config-ospf-router)#area 0ServerIronADX(config-ospf-router)#redistribution static

Syntax: [no] redistribution static

To enable redistribution of static routes for IPv6, enter commands such as the following:

ServerIronADX(config)#ipv6 router ospfServerIronADX(config-ospf6-router)#redistribute static

Syntax: [no] redistribute static



• Disabling network route advertisement for an interface associated with VIP RHI — The ip dont-advertise or ipv6 dont-advertise commands configure the ServerIron ADX to block advertisement of the network on the interface. If you do not block advertisement of the network, the ServerIron ADX will advertise a route to the network containing the VIP, even if the VIP itself is unavailable. After you enter the ip dont-advertise command, the ServerIron ADX advertises only a host route to the VIP address. Therefore, if the VIP is not healthy, the ServerIron ADX will remove the static host route for the VIP address and also not advertise a network route for the network containing the VIP address.

NOTEWhen using the dont-advertise commands, the IP or IPv6 and subnet mask length should be the same as the interface IP or IPv6 and subnet mask length.

For IPv4, enter commands similar to the following.

ServerIronADX(config)#interface ethernet 4/15ServerIronADX(config-if-4/15)#ip address 10.1.1.99 255.255.255.0 ServerIronADX(config-if-4/15)#ip dont-advertise 10.1.1.99 255.255.255.0

Syntax: ip dont-advertise ip-addr mask I ip-addr/mask-bits

For IPv6enter commands similar to the following.

ServerIronADX(config)#interface loopback 1ServerIronADX(config-lbif-1)#ipv6 address 2001:db8::1/64 ServerIronADX(config-if-3/1)#ipv6 dont-advertise 2001:db8::1/64

Syntax: ipv6 dont-advertise ipv6-prefix/prefix length

The following example of the display from the show ipv6 route command shows how dont-advertise routes are represented for IPv6 routes. As shown, the route type for these routes is “C (N)”.

ServerIronADX-A(config-lbif-3)#show ipv6 routeIPv6 Routing Table - 5 entries:Type Codes: C - Connected, C(N) Connected(Dont-Advertise), S - Static, R - RIP, O - OSPF, B - BGP, D - RAType IPv6 Prefix Next Hop Router Interface Dis/MetricC 2001:DB8:3000::/64:: e 1 0/0C 2001:DB8:4000::/64:: ve 40 0/0C(N) 2001:DB8:4444::/64:: loopback 1 0/0S 2001:DB8:4444::/96 2001:DB8:4444::110 loopback 1 1/1C(N) 2001:DB8:6020::/78:: loopback 3 0/0



• Loopback interface, non-dangling VIPs, or dangling VIPs - For VIP RHI to work, you must configure a loopback interface or VE interface in the same subnet as the VIP subnet (non-dangling VIP) or configure the VIP without any associated interface (dangling VIP described in “VIP RHI with dangling subnets” on page 172).

The loopback interface or VE interface must have the ip dont-advertise command configured. The following example configures a loopback interface to support two VIPs.

Virtual server 1 IP: 10.1.152.65

Virtual server 2 IP: 10.1.152.66

If the subnet of the VIPs is /30 then you need to configure either a VE interface or a loopback interface as follows:

ServerIronADX1000(config)#interface loopback 2ServerIronADX1000(config-lbif-2)#ip address 10.1.152.67/28ServerIronADX1000(config-lbif-2)#ip dont-advertise 10.1.152.67/28

Enabling or disabling VIP RHI

The ServerIron ADX can enable VIP RHI globally or at the VIP sublevel for IPv4 hosts, IPv6 hosts or both. To enable VIP RHI feature globally for all IPv4 VIPs, enter commands such as the following.

ServerIronADX(config)#server global-advertise-vip-route v4-only

To enable VIP RHI feature globally for all IPv6 VIPs, enter commands such as the following.

ServerIronADX(config)#server global-advertise-vip-route v6-only

Syntax: [no] server global-advertise-vip-route [v4-only | v6-only | both]

The v4-only parameter enables VIP RHI globally or at the VIP sublevel for IPv4 hosts.

The v6-only parameter enables VIP RHI globally or at the VIP sublevel for IPv6 hosts.

The both parameter enables VIP RHI globally or at the VIP sublevel for IPv4 and IPv6 hosts.

If none of these parameters are specified, VIP RHI is enabled globally for IPv4 hosts only.

NOTEWhere VIP hosts are classified as healthy, the ServerIron ADX injects static host/subnet routes. If a VIP is found to be unhealthy, RHI withdraws the static host/subnet route but the feature remains enabled. Using the no server global-advertise-vip-route command (IPv4 and IPv6) disables RHI and causes all routes that were injected by RHI because of the global-advertise command to be withdrawn. Routes injected by local advertise will still be in effect and will override the global advertise setting.

To enable VIP RHI for an individual virtual server, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip vs1ServerIronADX(config-vs-vs1#advertise-vip-route

Syntax: [no] advertise-vip-route



NOTEWhere VIP hosts are classified as healthy, the ServerIron ADX injects a static host/subnet routes only for the VIP specified by the advertise-vip-route command. If a VIP is found to be unhealthy, RHI withdraws the static host/subnet route for the host of the configured VIP but the feature remains enabled. Using the no advertise-vip-route command causes any routes for this VIP host injected by RHI to be withdrawn.

To disable VIP RHI for an individual virtual server, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip vs1ServerIronADX(config-vs-vs1#disable-advertise-vip-routeServerIronADX(config-vs-vs1)#end

Syntax: [no] disable-advertise-vip-route

This command is useful if you need to enable VIP RHI globally and disable it for a few virtual servers.

NOTEDue to certain design restrictions, we advise that users turn off the RHI feature before modifying an interface configuration (on the interface to which the VIP is attached). After changes have been made to the interface configuration, you can turn the RHI feature on again. Following this method allows new VIP static routes to be recomputed and advertised while the old VIP routes are withdrawn. Use the Global and Local VIP advertise commands to turn the RHI on and off.

Defining the health of a VIP port

There are two options for defining VIP port health:

• By default, a VIP port will be considered healthy as long as there is at least one healthy real server port bound to it.

• You can define the percentage of bound real server ports that must be healthy in order to consider the VIP port healthy.

When you define the percentage of bound real server ports that must be healthy in order to consider the VIP port healthy, you can define this setting globally or per-VIP.

Defining the health of a VIP port globallyTo globally define the percentage of bound real server ports that must be healthy to consider a VIP port healthy, enter commands such as the following.

ServerIronADX(config)#server rhi-active-bindings-threshold 20

Syntax: [no] server rhi-active-bindings-threshold percent

Defining the health of a VIP port per VIPTo define the percentage of bound real server ports that must be healthy to consider a VIP port healthy for a specific VIP, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip dns-p1ServerIronADX(config-vs-dns-p1)#rhi-active-bindings-threshold 30

NOTEThe VIP level configuration applies to all Virtual ports on the configured virtual server.



Syntax: [no] rhi-active-bindings-threshold percent

A valid range for percent is 1 through 100.

If the percent variable is not set, the percentage is 0. In this case, the default method will be used to determine the health of the VIP port. For example, a VIP port will be considered healthy as long as there is at least one healthy real server port bound to it.

As another example, consider a virtual server 10.1.1.101 with the port http command configured. This port http of the virtual server is bound to port http of real server 10.1.1.15 and port http of real server 10.1.1.44. If you have not configured any active bindings threshold percentage, then port http of VIP 10.1.1.101 will be considered healthy as long as at least one of the two bound real server ports is healthy.

If you configure an active bindings threshold percentage of 100, then this setting requires all bound real server ports for the VIP port to be healthy in order to consider the VIP port healthy. If real server port http for real server 10.1.1.15 goes down, then VIP port http is no longer considered healthy because only 50 percent of the bound real server ports are healthy. The configuration in this example requires 100 percent of the bound real server ports to be up in order to consider the VIP port as healthy.

Defining the health of a VIP

Multiple VIP ports can be configured for a VIP. There are two options provided for determining the health of a VIP:

• By default, a VIP will be considered healthy if all VIP ports for the VIP are healthy.

• You can specify a VIP to be considered healthy as long as there is at least one healthy VIP port.

To specify that a VIP should be considered healthy if at least one VIP port is healthy, enter commands such as the following.

ServerIronADX(config)#server rhi-one-vip-port-up

Syntax: [no] server rhi-one-vip-port-up

If this command is not configured, a VIP will be considered healthy only if all VIP ports are healthy.

NOTEIf a VIP port is not bound to any real server ports, it will not be used for deciding the health of the VIP.

If a VIP port is bound but you do not want to use it to determine the health of the VIP as described above, then configure the following for the VIP port.

ServerIronADXA(config)#server virtual-name-or-ip dns-p1ServerIronADXA(config-vs-dns-p1)#port ftp rhi-dont-use-port

Syntax: [no] port port rhi-dont-use-port

As another example, assume the port http and port ftp commands have been configured for virtual server vs1. You then bind port ftp of real server rs1 and port ftp of real server rs2 to port ftp of virtual server vs1. Similarly, you bind port http of real server rs1 and port http of real server rs2 to port http of virtual server vs1. If you need to base the health of the VIP vs1 only on the health of the VIP port http, then you can configure the following for the port ftp.

ServerIronADX(config)#server virtual-name-or-ip vs1ServerIronADX(config-vs-dns-p1)#port ftp rhi-dont-use-port



As a result, only the health of port http of virtual server vs1 will be used to determine the health of virtual server vs1 and consequently to determine if the VIP route for vs1 should be injected or withdrawn.

Configuring the VIP RHI Route Mask Length

You can configure the subnet mask length that VIP RHI injects into the routing table for a specific virtual server by entering a command such as the following.

ServerIronADX(config)#server virt virt-2ServerIronADX(config-vs-virt-2)#vip-route-subnet-mask-length 28

Syntax: [no] vip-route-subnet-mask-length length

The ipv4-subnet-mask-length variable specifies the IPv4 subnet mask length of VIP RHI injected route for this virtual server. This parameter must have a value between interface subnet mask length and 32.

The ipv6-subnet-mask-length variable specifies the IPv6 subnet mask length of VIP RHI injected route for this virtual server. This parameter must have a value between interface subnet mask length and 128.

The server global-vip-route-mask-length command that configured the VIP RHI route mask length at a global level has been deprecated. This configuration will be translated to VIP level mask length under each individual VIP during image upgrade.

NOTEThe VIP-RHI mask length should not be less than the interface subnet mask length.

Depending on the interface mask length and the vip-route-mask length there can be either a host route or single/dual subnet routes to this VIP host.

ServerIronADX(config-vs-virt-2)#vip-route-subnet-mask-length 28

For example, If you have a VIP host with the IPv6 address “2001:DB8::10” configured over a loopback interface with the IPv6 address “2001:DB8::1/64” will, by default, RHI inject a static host route as shown.

S 2001:DB8::10/128 2001:DB8::10 loopback 1 1/1

If you configure a vip-route-mask-length as “96” then when this VIP becomes healthy, an IPv6 subnet route with a mask length of “96” is advertised as shown.

S 2001:DB8::/96 2001:DB8::10 loopback 1 1/1

Where a user configures the vip-route-subnet-mask-length to the same values as the interface mask length, RHI injects two subnet static routes instead of one. In this situation the user will see two routes instead of one. For example, if the interface subnet mask length is “64” and the user configures the vip-subnet-mask-length as “64”, two routes will be advertised as shown below.

S 2001:DB8::/65 2001:DB8::10 loopback 1 1/1S 2001:DB8::80:0:0:0/65 2001:DB8::10 loopback 1 1/1

Please note the subnet mask length of the above routes. When the user changes the VIP subnet mask length to and from being equal to the interface subnet mask length, the VIP static route injected will be corrected between dual routes and a single static route. This dual route extension was created to accommodate a larger range/number of VIP hosts within a subnet.



NOTEOne exception to the above dual route case is where value of the vip-route-subnet-mask-length command exceeds 125. In this situation, RHI will only inject host static routes.

NOTEUse caution while configuring the vip-route-subnet-mask-length command value. Please make sure that the VIP subnets do not overlap with each other.

VIP RHI with dangling subnetsNormally a VIP with RHI should have an associated interface with an interface address (IPv4 or IPv6) belonging to the VIP subnet. This means that at least one IP address belonging to the VIP subnet is consumed by the interface and cannot be used as a public address for the VIP server and RHI has to depend on having an associated interface.

A user who does not wish to waste one public IP address to the interface can do so without adding any IP address in the VIP subnet. In this situation the VIP is deemed to be a “dangling VIP” (not associated with any interface). If the user adds an IP address in the VIP subnet to an interface, such a VIP is called a “non-dangling VIP”. The ServerIron ADX supports both dangling and non-dangling VIPs. RHI determines the mode of the VIP at the time when advertise is enabled. The routes advertised also differ slightly in case of dangling VIPs as described in the following:

• Non-dangling VIPs: RHI will associate with the matching interface and set boundaries for the VIP route to be advertised. In this case, RHI makes sure that it does not advertise a route bigger than the size of the associated subnet itself. This also includes advertising of dual routes. This configuration also allows dynamic-sym-priority to be bound with an associated interface status.

• Dangling VIPs: RHI will use the VIP-route-subnet-mask-length and blindly advertise a static route of that size. A user will see static routes with the next hop address as 255.255.255.255 in case of IPv4 VIP and :: (invalid IPv6 address) for an IPv6 VIP. In case of IPv4 the port value of the route shows “drop” and for IPv6 the port is “null”. In this mode dynamic-sym-priority is not bound to interface status.

The following examples display how the output from the show ip route command will differ for the same destination address for non-dangling and dangling VIPs. Notice that for dangling VIPs the “gateway” is specified as a non-valid route (IPv4 and IPv6). Also, the “interface” is specified as “drop” for IPv4 and “null” for IPv6. Display of these values is normal for dangling VIPs.

Example of non-dangling VIPs

ServerIronADX#show ip routeTotal number of IP routes: 1Start index: 1 B:BGP D:Connected R:RIP S:Static O: OSPF *:CandidatedefaultDestination NetMask Gateway Port Cost Type

1 10.1.1.0 255.255.255.0 10.1.1.105 1b1 1 S

ServerIronADX#show ipv6 routeIPv6 Routing Table - 1 entrie:Type Codes: C - Connected, S - Static, R - RIP, O - OSPF, B - BGP, D - RA Typ IPv6 Prefix Next Hop Router Interface Dis/MetricS 2001:db8::10/128 2001:db8::10 loopback 1 1/1



Example of dangling VIPs

Important caveats.• Order of configuration is important in RHI. A user should choose between the two available

modes (dangling and non-dangling) first and configure the interface and VIP RHI accordingly.

• Changing the interface configuration (for example: adding or deleting an IP address in the VIP subnet or disabling the interface) while the RHI is active is not recommended.

• To change the mode of the VIP, a user must remove RHI advertise first, change the interface configuration and then re-enable the RHI configuration. RHI computes the mode only at the time of enabling the RHI advertise option.

VIP RHI and high availability topologies• Hot Standby topology - VIP RHI is only supported on the ServerIron Router (R) platform. A Hot

Standby topology is not supported for the R code base. Therefore, VIP RHI is not applicable to Hot Standby topologies.

• Symmetric and sym-active topologies - In both symmetric and sym-active topologies, only the owner of the VIP (the VIP in the active state) will inject the route. In this topology, the ServerIron will withdraw the VIP route when a VIP transitions from Active to standby state. Similarly, the ServerIron will inject the VIP route when a VIP transitions from Standby to Active, if the VIP is healthy at the time of the transition.

Optionally, you can enable ServerIron to inject a VIP route inside the routing process regardless of its VIP ownership status. Enter the following command if you want to enable both ServerIrons to inject VIP route regardless of its ownership.

ServerIronADX(config)#server rhi-inject-always

Syntax: [no] server rhi-inject-always

Displaying route type

When VIP RHI is enabled for a virtual server, the VIP host route type is shown as "S:Static". The reason for doing this is the ServerIron ADX can use redistribute static of routing protocols (OSPF and RIP for IPv4 and OSPFv3 for IPv6) to advertise the VIP host route.

When the network route advertisement is disabled, the ServerIron ADX shows the route's type as “D(N).”

ServerIronADX#show ip routeTotal number of IP routes: 1Start index: 1 B:BGP D:Connected R:RIP S:Static O: OSPF *:CandidatedefaultDestination NetMask Gateway Port Cost Type10.1.1.0 255.255.255.0 255.255.255.255 drop 1 S

ServerIronADX#show ipv6 routeIPv6 Routing Table - 1 entrie:Type Codes: C - Connected, S - Static, R - RIP, O - OSPF, B - BGP, D - RA Typ IPv6 Prefix Next Hop Router Interface Dis/MetricS 2001:db8::/64 :: null 1/1



The following output of the show ip route command is from a ServerIron ADX with VIP RHI enabled..

The following snap shot of the show ipv6 route command was taken from a ServerIron ADX with VIP RHI enabled.

NOTESome administrators might view this approach as a contradiction to the basic definition of a route type. The route type of a network that is owned by an ServerIron ADX (router) is usually shown as "D:connected" and a manually added static route type is to be shown as “S:Static.”

ServerIronADX#show ip route Total number of IP routes: 11 Start index: 1 B:BGP D:Connected R:RIP S:Static O:OSPF *:Candidate default Destination NetMask Gateway Port Cost Type 1 10.20.1.0 255.255.255.0 0.0.0.0 v2 1 D 2 10.30.0.0 255.255.0.0 10.40.1.101 v1 2 O 3 10.40.1.0 255.255.255.0 0.0.0.0 v1 1 D 4 10.50.1.0 255.255.255.0 0.0.0.0 v4 1 D(N) 5 10.60.1.0 255.255.255.0 0.0.0.0 v3 1 D(N) 6 10.60.1.10 255.255.255.255 10.60.1.10 v3 1 S 7 10.70.1.0 255.255.255.0 0.0.0.0 3/12 1 D(N) 8 10.70.1.10 255.255.255.255 10.70.1.10 3/12 1 S 9 10.80.1.0 255.255.255.0 10.20.1.101 v2 2 O 10 10.90.1.0 255.255.255.0 0.0.0.0 3/12 1 D(N) 11 10.90.1.10 255.255.255.255 10.90.1.10 3/12 1 S

ServerIronADX(config)#show ipv6 routeIPv6 Routing Table - 6 entries:Type Codes: C - Connected, C(N) Connected(Dont-Advertise), S - Static, R - RIP, O - OSPF, B - BGP, D - RAType IPv6 Prefix Next Hop Router Interface Dis/MetricC 2001:db8:2001::/64:: ve 20 0/0S 2001:db8:3001::/642001:db8:4001::101ve 40 1/1C 2001:db8:3500::/64:: e 1/11 0/0C 2001:db8:4001::/64:: ve 40 0/0C(N)2001:db8:5000::/64:: loopback 1 0/0C 2001:db8:bbbb::/64:: e 1/9T 0/0Dob-4U-SI-A(config)#



Configuration examples

Both ServerIron ADX sites working in primary modeFigure 22 shows both the ServerIron ADXs working in the primary mode.

FIGURE 22 Primary mode

Site 1 configurationver 09.3.00b265TD4!module 1 bi-0-port-wsm2-management-modulemodule 2 bi-jc-8-port-gig-modulemodule 3 bi-jc-16-port-gig-copper-modulemodule 4 bi-jc-16-port-gig-copper-module!



global-protocol-vlan!!server predictor round-robinserver global-advertise-vip-route v4-onlyserver rhi-active-bindings-threshold 80

server port 21 tcpserver port 80 tcpserver port 53 udpserver port 161 udpserver port 25 tcpserver port 443 tcpserver port 8601 tcp!!server real rs1 10.20.1.40 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real rs2 10.20.1.41 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server remote-name test 10.30.1.40 source-nat port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real Web1 10.60.1.40 port 8601!



server real Web2 10.60.1.41 port 8601!server real Web3 10.60.1.42 port 8601!server real Web4 10.60.1.43 port 8601!server real Web5 10.60.1.44 port 8601!server real Web6 10.60.1.45 port 8601!server real Web7 10.60.1.46 port 8601!server real Web8 10.60.1.47 port 8601!server real Web9 10.60.1.48 port 8601!server real Web10 10.60.1.49 port 8601!server real wr1 10.50.1.40 port http port http url "HEAD /"!server real wr2 10.50.1.41 port http port http url "HEAD /"!server real wr3 10.50.1.42 port http port http url "HEAD /"!server real wr4 10.50.1.43 port http port http url "HEAD /"!server real wr5 10.50.1.44 port http port http url "HEAD /"!server real wr6 10.50.1.45 port http port http url "HEAD /"!server real wr7 10.50.1.46 port http port http url "HEAD /"!server real wr8 10.50.1.47 port http port http url "HEAD /"!server real wr9 10.50.1.48



port http port http url "HEAD /"!server real wr10 10.50.1.49 port http port http url "HEAD /"!server remote-name rem1 10.80.1.40 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!server remote-name rem2 10.80.1.41 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!!server virtual-name-or-ip vip60 10.60.1.10 port http bind http Web1 8601 Web2 8601 Web3 8601 Web4 8601 bind http Web5 8601 Web6 8601 Web7 8601 Web8 8601 bind http Web9 8601 Web10 8601!server virtual-name-or-ip vip50 10.50.1.10 port http bind http wr1 http wr2 http wr3 http wr4 http bind http wr5 http wr6 http wr7 http wr8 http bind http wr9 http wr10 http!server virtual-name-or-ip vip70 10.70.1.10 port http port smtp port ftp port dns port snmp port mms port rtsp bind http test http bind smtp test smtp bind ftp test ftp bind dns test dns bind snmp test snmp bind mms test mms bind rtsp test rtsp!server virtual-name-or-ip vip90 10.90.1.10 vip-route-subnet-mask-length 28



port dns port snmp port http port ftp bind dns rem1 dns rem2 dns bind snmp rem1 snmp rem2 snmp bind http rem1 8601 rem2 8601 bind ftp rem1 ftp rem2 ftp!server virtual-name-or-ip vip20 10.20.1.10 disable-advertise-vip-route port http port dns port snmp port ftp bind http rs1 http rs2 http bind dns rs1 dns rs2 dns bind snmp rs1 snmp rs2 snmp bind ftp rs1 ftp rs2 ftp!!vlan 1 name DEFAULT-VLAN by port!vlan 10 by port untagged ethe 2/1 to 2/4 router-interface ve 1!vlan 20 by port untagged ethe 4/1 to 4/16 router-interface ve 2!vlan 30 by port tagged ethe 2/5 untagged ethe 2/8 router-interface ve 3!vlan 40 by port tagged ethe 2/5 untagged ethe 2/6 to 2/7 router-interface ve 4!!hostname Site1-SIlogging buffered 1000mirror ethernet 4/12!server session-debug 100000auto-cam-repaintpram-write-retry!router ospf area 0 metric-type type1 redistribution connected redistribution static !interface loopback 1 ip address 10.100.100.100 255.255.255.255 ip ospf area 0!



interface ethernet 2/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/5 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 3/12 ip address 10.70.1.120 255.255.255.0 ip dont-advertise 10.70.1.120 255.255.255.0 ip address 10.90.1.120 255.255.255.0 ip dont-advertise 10.90.1.120 255.255.255.0 !interface ethernet 4/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/16 mon ethe 4/12 input mon ethe 4/12 output!interface ve 1 ip address 10.40.1.120 255.255.255.0 ip address 10.40.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 2 ip address 10.20.1.120 255.255.255.0 ip address 10.20.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 3 ip address 10.60.1.120 255.255.255.0 ip dont-advertise 10.60.1.120 255.255.255.0 ip address 10.60.1.121 255.255.255.0 secondary ip dont-advertise 10.60.1.121 255.255.255.0 !interface ve 4 ip address 10.50.1.120 255.255.255.0 ip dont-advertise 10.50.1.120 255.255.255.0 ip address 10.50.1.121 255.255.255.0 secondary ip dont-advertise 10.50.1.121 255.255.255.0 !!end



Site 2 configuration

module 1 bi-0-port-wsm2-management-modulemodule 2 bi-jc-8-port-gig-modulemodule 3 bi-jc-16-port-gig-copper-modulemodule 4 bi-jc-16-port-gig-copper-module!global-protocol-vlan!!server predictor round-robinserver global-advertise-vip-route v4-onlyserver rhi-active-bindings-threshold 80

server port 21 tcp

server port 80 tcp

server port 53 udp

server port 161 udp

server port 25 tcp

server port 443 tcp

server port 8601 tcp!!!server real rs1 10.120.1.40 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real rs2 10.120.1.41 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!



server remote-name test 10.130.1.40 source-nat port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real Web1 10.60.1.40 port 8601!server real Web2 10.60.1.41 port 8601!server real Web3 10.60.1.42 port 8601!server real Web4 10.60.1.43 port 8601!server real Web5 10.60.1.44 port 8601!server real Web6 10.60.1.45 port 8601!server real Web7 10.60.1.46 port 8601!server real Web8 10.60.1.47 port 8601!server real Web9 10.60.1.48 port 8601!server real Web10 10.60.1.49 port 8601!server real wr1 10.50.1.40 port http port http url "HEAD /"!server real wr2 10.50.1.41 port http port http url "HEAD /"!server real wr3 10.50.1.42 port http port http url "HEAD /"!server real wr4 10.50.1.43 port http port http url "HEAD /"!server real wr5 10.50.1.44 port http



port http url "HEAD /"!server real wr6 10.50.1.45 port http port http url "HEAD /"!server real wr7 10.50.1.46 port http port http url "HEAD /"!server real wr8 10.50.1.47 port http port http url "HEAD /"!server real wr9 10.50.1.48 port http port http url "HEAD /"!server real wr10 10.50.1.49 port http port http url "HEAD /"!server remote-name rem1 10.180.1.40 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!server remote-name rem2 10.180.1.41 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!!server virtual-name-or-ip vip60 10.60.1.10 port http bind http Web1 8601 Web2 8601 Web3 8601 Web4 8601 bind http Web5 8601 Web6 8601 Web7 8601 Web8 8601 bind http Web9 8601 Web10 8601!server virtual-name-or-ip vip50 10.50.1.10 port http bind http wr1 http wr2 http wr3 http wr4 http bind http wr5 http wr6 http wr7 http wr8 http bind http wr9 http wr10 http!server virtual-name-or-ip vip70 10.70.1.10 port http port smtp



port ftp port dns port snmp port mms port rtsp bind http test http bind smtp test smtp bind ftp test ftp bind dns test dns bind snmp test snmp bind mms test mms bind rtsp test rtsp!server virtual-name-or-ip vip90 10.90.1.10 vip-route-subnet-mask-length 28 port dns port snmp port http port ftp bind dns rem1 dns rem2 dns bind snmp rem1 snmp rem2 snmp bind http rem1 8601 rem2 8601 bind ftp rem1 ftp rem2 ftp!server virtual-name-or-ip vip120 10.120.1.10 disable-advertise-vip-route port http port dns port snmp port ftp bind http rs1 http rs2 http bind dns rs1 dns rs2 dns bind snmp rs1 snmp rs2 snmp bind ftp rs1 ftp rs2 ftp!!vlan 1 name DEFAULT-VLAN by port!vlan 10 by port untagged ethe 2/1 to 2/4 router-interface ve 1!vlan 20 by port untagged ethe 4/1 to 4/16 router-interface ve 2!vlan 30 by port tagged ethe 2/5 untagged ethe 2/8 router-interface ve 3!vlan 40 by port tagged ethe 2/5 untagged ethe 2/6 to 2/7 router-interface ve 4!!hostname Site2-SIlogging buffered 1000mirror ethernet 4/12



!server session-debug 100000auto-cam-repaintpram-write-retry!router ospf area 0 metric-type type1 redistribution connected redistribution static !interface loopback 1 ip address 10.100.100.101 255.255.255.255 ip ospf area 0!interface ethernet 2/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/5 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 3/12 ip address 10.70.1.120 255.255.255.0 ip dont-advertise 10.70.1.120 255.255.255.0 ip address 10.90.1.120 255.255.255.0 ip dont-advertise 10.90.1.120 255.255.255.0 !interface ethernet 4/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/16 mon ethe 4/12 input mon ethe 4/12 output!interface ve 1 ip address 10.140.1.120 255.255.255.0 ip address 10.140.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 2 ip address 10.120.1.120 255.255.255.0 ip address 10.120.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 3 ip address 10.60.1.120 255.255.255.0 ip dont-advertise 10.60.1.120 255.255.255.0 ip address 10.60.1.121 255.255.255.0 secondary ip dont-advertise 10.60.1.121 255.255.255.0



!interface ve 4 ip address 10.50.1.120 255.255.255.0 ip dont-advertise 10.50.1.120 255.255.255.0 ip address 10.50.1.121 255.255.255.0 secondary ip dont-advertise 10.50.1.121 255.255.255.0 !end

Site 1 ServerIron ADX in primary mode and Site 2 in backup modeFigure 23 shows the Site 1 where the ServerIron ADX is in primary mode and in the Site 2 where the ServerIron ADX is in the backup mode.

FIGURE 23 Primary mode and backup mode



Site 1 configurationThe following configuration is only for virtual server vip60 (10.60.1.10).

!ver 09.3.00b269TD4!module 1 bi-0-port-wsm2-management-modulemodule 2 bi-jc-8-port-gig-modulemodule 3 bi-jc-16-port-gig-copper-modulemodule 4 bi-jc-16-port-gig-copper-module!global-protocol-vlan!!server predictor round-robinserver global-advertise-vip-route v4-onlyserver rhi-active-bindings-threshold 80

server port 21 tcp

server port 80 tcp

server port 53 udp

server port 161 udp

server port 25 tcp

server port 443 tcp

server port 8601 tcp!!server real rs1 10.20.1.40 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real rs2 10.20.1.41 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms



port rtsp!server remote-name test 10.30.1.40 source-nat port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real Web1 10.60.1.40 port 8601!server real Web2 10.60.1.41 port 8601!server real Web3 10.60.1.42 port 8601!server real Web4 10.60.1.43 port 8601!server real Web5 10.60.1.44 port 8601!server real Web6 10.60.1.45 port 8601!server real Web7 10.60.1.46 port 8601!server real Web8 10.60.1.47 port 8601!server real Web9 10.60.1.48 port 8601!server real Web10 10.60.1.49 port 8601!server real wr1 10.50.1.40 port http port http url "HEAD /"!server real wr2 10.50.1.41 port http port http url "HEAD /"!server real wr3 10.50.1.42 port http port http url "HEAD /"!server real wr4 10.50.1.43 port http port http url "HEAD /"!



server real wr5 10.50.1.44 port http port http url "HEAD /"!server real wr6 10.50.1.45 port http port http url "HEAD /"!server real wr7 10.50.1.46 port http port http url "HEAD /"!server real wr8 10.50.1.47 port http port http url "HEAD /"!server real wr9 10.50.1.48 port http port http url "HEAD /"!server real wr10 10.50.1.49 port http port http url "HEAD /"!server remote-name rem1 10.80.1.40 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!server remote-name rem2 10.80.1.41 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!!server virtual-name-or-ip vip60 10.60.1.10 port http bind http Web1 8601 Web2 8601 Web3 8601 Web4 8601 bind http Web5 8601 Web6 8601 Web7 8601 Web8 8601 bind http Web9 8601 Web10 8601!server virtual-name-or-ip vip50 10.50.1.10 port http bind http wr1 http wr2 http wr3 http wr4 http bind http wr5 http wr6 http wr7 http wr8 http bind http wr9 http wr10 http!server virtual-name-or-ip vip70 10.70.1.10



port http port smtp port ftp port dns port snmp port mms port rtsp bind http test http bind smtp test smtp bind ftp test ftp bind dns test dns bind snmp test snmp bind mms test mms bind rtsp test rtsp!server virtual-name-or-ip vip90 10.90.1.10 vip-route-subnet-mask-length 28 port dns port snmp port http port ftp bind dns rem1 dns rem2 dns bind snmp rem1 snmp rem2 snmp bind http rem1 8601 rem2 8601 bind ftp rem1 ftp rem2 ftp!server virtual-name-or-ip vip20 10.20.1.10 disable-advertise-vip-route port http port dns port snmp port ftp bind http rs1 http rs2 http bind dns rs1 dns rs2 dns bind snmp rs1 snmp rs2 snmp bind ftp rs1 ftp rs2 ftp!vlan 1 name DEFAULT-VLAN by port!vlan 10 by port untagged ethe 2/1 to 2/4 router-interface ve 1!vlan 20 by port untagged ethe 4/1 to 4/16 router-interface ve 2!vlan 30 by port tagged ethe 2/5 untagged ethe 2/8 router-interface ve 3!vlan 40 by port tagged ethe 2/5 untagged ethe 2/6 to 2/7 router-interface ve 4!!hostname Site1-SIlogging buffered 1000



mirror ethernet 4/12!server session-debug 100000auto-cam-repaintpram-write-retry!router ospf area 0 metric-type type1 redistribution connected redistribution static !interface loopback 1 ip address 10.100.100.100 255.255.255.255 ip ospf area 0!interface ethernet 2/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/5 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 3/12 ip address 10.70.1.120 255.255.255.0 ip dont-advertise 10.70.1.120 255.255.255.0 ip address 10.90.1.120 255.255.255.0 ip dont-advertise 10.90.1.120 255.255.255.0!interface ethernet 4/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/16 mon ethe 4/12 input mon ethe 4/12 output!interface ve 1 ip address 10.40.1.120 255.255.255.0 ip address 10.40.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 2 ip address 10.20.1.120 255.255.255.0 ip address 10.20.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 3 ip address 10.60.1.120 255.255.255.0 ip dont-advertise 10.60.1.120 255.255.255.0 ip address 10.60.1.121 255.255.255.0 secondary



ip dont-advertise 10.60.1.121 255.255.255.0!interface ve 4 ip address 10.50.1.120 255.255.255.0 ip dont-advertise 10.50.1.120 255.255.255.0 ip address 10.50.1.121 255.255.255.0 secondary ip dont-advertise 10.50.1.121 255.255.255.0!end

Site 2 configuration!ver 09.3.00b269TD4!module 1 bi-0-port-wsm2-management-modulemodule 2 bi-jc-8-port-gig-modulemodule 3 bi-jc-16-port-gig-copper-modulemodule 4 bi-jc-16-port-gig-copper-module!global-protocol-vlan!!healthck Site1-chk icmp dest-ip 10.40.1.120

healthck Site1-NOT boolean not Site1-chk

healthck Web1-8601-chk tcp dest-ip 10.60.1.40 port 8601 protocol http protocol http url "HEAD /" interval 20 retries 4 l7-check



healthck Web4-8601-chk tcp dest-ip 10.60.1.43 port 8601 protocol http



protocol http url "HEAD /" interval 20 retries 4 l7-check







healthck Web1-chk boolean



and Site1-NOT Web1-8601-chk

healthck Web2-chk boolean and Site1-NOT Web2-8601-chk








healthck Web10-chk boolean and Site1-NOT Web10-8601-chk!server predictor round-robinserver global-advertise-vip-route v4-onlyserver rhi-active-bindings-threshold 80

server port 21 tcpserver port 80 tcpserver port 53 udpserver port 161 udpserver port 25 tcpserver port 443 tcpserver port 8601 tcp!!server real rs1 10.120.1.40 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!



server real rs2 10.120.1.41 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server remote-name test 10.130.1.40 source-nat port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real Web1 10.60.1.40 port 8601 port 8601 healthck Web1-chk!server real Web2 10.60.1.41 port 8601 port 8601 healthck Web2-chk!server real Web3 10.60.1.42 port 8601 port 8601 healthck Web3-chk!server real Web4 10.60.1.43 port 8601 port 8601 healthck Web4-chk!server real Web5 10.60.1.44 port 8601 port 8601 healthck Web5-chk!server real Web6 10.60.1.45 port 8601 port 8601 healthck Web6-chk!server real Web7 10.60.1.46 port 8601 port 8601 healthck Web7-chk!server real Web8 10.60.1.47 port 8601 port 8601 healthck Web8-chk!server real Web9 10.60.1.48 port 8601 port 8601 healthck Web9-chk!server real Web10 10.60.1.49



port 8601 port 8601 healthck Web10-chk!server real wr1 10.50.1.40 port http port http url "HEAD /"!server real wr2 10.50.1.41 port http port http url "HEAD /"!server real wr3 10.50.1.42 port http port http url "HEAD /"!server real wr4 10.50.1.43 port http port http url "HEAD /"!server real wr5 10.50.1.44 port http port http url "HEAD /"!server real wr6 10.50.1.45 port http port http url "HEAD /"!server real wr7 10.50.1.46 port http port http url "HEAD /"!server real wr8 10.50.1.47 port http port http url "HEAD /"!server real wr9 10.50.1.48 port http port http url "HEAD /"!server real wr10 10.50.1.49 port http port http url "HEAD /"!server remote-name rem1 10.180.1.40 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!server remote-name rem2 10.180.1.41 port 8601 port ftp port smtp port ssl port dns



port dns zone "example9.com" port snmp port mms port rtsp!!server virtual-name-or-ip vip60 10.60.1.10 port http bind http Web1 8601 Web2 8601 Web3 8601 Web4 8601 bind http Web5 8601 Web6 8601 Web7 8601 Web8 8601 bind http Web9 8601 Web10 8601!server virtual-name-or-ip vip50 10.50.1.10 port http bind http wr1 http wr2 http wr3 http wr4 http bind http wr5 http wr6 http wr7 http wr8 http bind http wr9 http wr10 http!server virtual-name-or-ip vip70 10.70.1.10 port http port smtp port ftp port dns port snmp port mms port rtsp bind http test http bind smtp test smtp bind ftp test ftp bind dns test dns bind snmp test snmp bind mms test mms bind rtsp test rtsp!server virtual-name-or-ip vip90 10.90.1.10 vip-route-subnet-mask-length 28 port dns port snmp port http port ftp bind dns rem1 dns rem2 dns bind snmp rem1 snmp rem2 snmp bind http rem1 8601 rem2 8601 bind ftp rem1 ftp rem2 ftp!server virtual-name-or-ip vip120 10.120.1.10 disable-advertise-vip-route port http port dns port snmp port ftp bind http rs1 http rs2 http bind dns rs1 dns rs2 dns bind snmp rs1 snmp rs2 snmp bind ftp rs1 ftp rs2 ftp!!vlan 1 name DEFAULT-VLAN by port!vlan 10 by port



untagged ethe 2/1 to 2/4 router-interface ve 1!vlan 20 by port untagged ethe 4/1 to 4/16 router-interface ve 2!vlan 30 by port tagged ethe 2/5 untagged ethe 2/8 router-interface ve 3!vlan 40 by port tagged ethe 2/5 untagged ethe 2/6 to 2/7 router-interface ve 4!!hostname Site2-SIlogging buffered 1000mirror ethernet 4/12!server session-debug 100000auto-cam-repaintpram-write-retry!router ospf area 0 metric-type type1 redistribution connected redistribution static !interface loopback 1 ip address 10.100.100.101 255.255.255.255 ip ospf area 0!interface ethernet 2/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/5 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 3/12 ip address 10.70.1.120 255.255.255.0 ip dont-advertise 10.70.1.120 255.255.255.0 ip address 10.90.1.120 255.255.255.0 ip dont-advertise 10.90.1.120 255.255.255.0!interface ethernet 4/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/2 mon ethe 4/12 input


Application-specific SLB considerations 2

mon ethe 4/12 output!interface ethernet 4/16 mon ethe 4/12 input mon ethe 4/12 output!interface ve 1 ip address 10.140.1.120 255.255.255.0 ip address 10.140.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 2 ip address 10.120.1.120 255.255.255.0 ip address 10.120.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 3 ip address 10.60.1.120 255.255.255.0 ip dont-advertise 10.60.1.120 255.255.255.0 ip address 10.60.1.121 255.255.255.0 secondary ip dont-advertise 10.60.1.121 255.255.255.0!interface ve 4 ip address 10.50.1.120 255.255.255.0 ip dont-advertise 10.50.1.120 255.255.255.0 ip address 10.50.1.121 255.255.255.0 secondary ip dont-advertise 10.50.1.121 255.255.255.0!end

Application-specific SLB considerations

RTSP server Load BalancingThe ServerIron ADX natively understands protocol RTSP and provides load balancing for it. The ServerIron ADX can also provide Layer 7 health checks for RTSP. Refer to “RTSP” on page 229 for details on Layer 7 health checks for RTSP.

If RTSP is bound to an unknown port, use the following command to provide RTSP server load balancing.

ServerIronADX(config)#server rtsp-for-unknown-port

Syntax: [no] server rtsp-for-unknown-port

NOTEThe ServerIron ADX supports RTSP client port values of up to 9999. If the client is using a port number above 9999, you must configure the client to use a lower port value.


Show and debug commands2

Deletion of UDP data session along with TCP control session for RTSPThe ServerIron ADX tracks both control and data sessions for RTSP regardless of the underlying transport layer (TCP or UDP) used by these sessions. When the system deletes an RTSP control session (TCP based), it also deletes the respective data session (which can be UDP based).

Use the following command to enable this functionality.

ServerIronADX(config)#server rtsp-delete-udp-with-tcp-sess

Syntax: [no] server rtsp-delete-udp-with-tcp-sess

TFTP load balancingTFTP load balancing is supported with health checks.

The ServerIron ADX can conduct Layer 3 and Layer 4 health checks for TFTP ports.

When you configure a TFTP port and bind it to a Virtual server, the ServerIron ADX does a Layer 3 check, and if this check passes, it does a Layer 4 check.

To check the health of a TFTP port, the ServerIron ADX sends out a request for the SIcheck.txt file. The ServerIron ADX does not actually interpret the reply packet. As long as it does not get an "ICMP dest or port unreachable" message, the ServerIron keeps the TFTP port up. If it gets an "ICMP unreachable" message, the ServerIron ADX brings the TFTP port down.

Show and debug commandsRefer to Appendix C, “SLB Show and Debug Commands” for a full list of show and debug commands.

SLB configuration examplesRefer to Appendix D, “SLB Configuration Examples” for a full list of configuration examples.


Displaying the BP distribution 2

Displaying the BP distributionTo show how traffic is distributed across the multiple barrel processors for a given flow (IP addresses and L4 ports), use the following syntax:

Syntax: show bp-distribution type-of-traffic source-ip dest-ip source-l4-port dest-l4-port protocol

The type-of-traffic variable can take various values depending on the configuration parameters of the incoming traffic flow.

The type-of-traffic variable values are listed below.

The following example shows how to calculate the BP for a reverse-SLB flow coming from Real-Server (10.1.1.1:80) to Source-NAT-IP (10.5.5.5).

ServerIronADX(config)#show bp-distribution source-ip 10.1.1.1 10.5.5.5 80 2048 0 Packets for the specified flow map to: BP 1/1

It displays which barrel processor the particular flow is landing on. The command takes IP addresses in either IPv4 or IPv6 format.

all Specifies the Catch-ALL entry due to Dynamic-NAT, FWLB, cpu-forward

cache-vip Specifies the Cache-VIP entry

frag Specifies the Fragmentation entry

fwlb Specifies the FWLB entry

manual-holddown Specifies the Manual-Holddown entry

real-server Specifies the Real-Server entry (Reverse-SLB traffic)

source-ip Specifies the Source-IP entry (Reverse-SLB traffic with Source-NAT)

static-nat Specifies the Static-NAT entry (Forward Static-NAT traffic)

static-nat-reverse Specifies the Reverse Static-NAT entry (Reverse Static-NAT traffic)

syn-def Specifies the Syn-Def entry

syn-proxy Specifies the Syn-Proxy entry

tcs Specifies the TCS entry

vip Specifies the VIP entry (Forward SLB traffic)

vip-protection Specifies the VIP-Protection entry


Windows Terminal Server with L7 persistence2

Windows Terminal Server with L7 persistenceWindows Terminal Server load balancing with persistence allows you to reconnect when disconnected from an already established connection to the session directory on the Windows 2003 terminal server.

This section contains the following sections:

• “Understanding windows terminal server” on page 202

• “Configuring Windows Terminal Server” on page 204

Understanding windows terminal serverIn a load balancing environment, the load balancer needs to be aware of the protocol to redirect the session to the right server.

Figure 24 shows how Windows Terminal Server load balancing with persistence works in the case of a new session.

FIGURE 24 New session scenario

When the new connection is made, the ServerIron ADX load balances it to one of the bound terminal servers. R2 in the example above.

On receiving the client logon, R2 checks with the session directory to see if the username exists in its database. Because this user had not previously established a session, the logon is established with R2.

R2 forwards a token to the user with the server IP address. The client now connects to the virtual server (VIP), and includes the token.

The ServerIron ADX inspects this token and then establishes a connection with the server that the token identifies.


Windows Terminal Server with L7 persistence 2

Figure 25 shows how Windows Terminal Server load balancing with persistence works in the case of a disconnected session.

FIGURE 25 Disconnected session scenario

The ServerIron ADX load balances the initial connection to one of its bound servers.

When the user logs on, the terminal server that receives this request, checks with the session directory to see if there is an established session in its database. The session directory communicates the same information to the terminal server.

Because the user has an established session with another server, the terminal server forwards a token to the user with the IP address of the server that it had disconnected from or had a failed session.

The user now connects to the VIP and uses the token with the server IP to which it needs to be connected.

After inspecting the token, the ServerIron ADX directs the server to the IP in the token rather than load balancing the request.

NOTEThis IP port should be one of the servers bound to the VIP. Otherwise, the ServerIron ADX does not direct the request.

NOTE The IP address redirection feature on the terminal server session directory needs to be turned OFF for Windows Terminal Server to work. If IP address redirection is ON, the client tries to establish the session with the server directly after receiving the token. Only with Windows Terminal Server OFF, is a routing token for redirection used. The client connects to the VIP of SI and uses the token for redirection.


Windows Terminal Server with L7 persistence2

Configuring Windows Terminal ServerWindows Terminal Server is not enabled by default. The following example shows how to configure Windows Terminal Server.

ServerIron(config)#server virtual-name-or-ip VIP-001 10.10.1.103ServerIron(config-vs-VIP-001)#port 3389 win-term-serv

Syntax: server virtual-name-or-ip [name] ip-address

Syntax: port num win-term-serv



Chapter

3
Stateless Server Load Balancing
OverviewThis chapter describes server load balancing configuration options that are “stateless.” Stateless SLB does not use session table entries for the TCP or UDP sessions between the ServerIron ADX and clients or real servers.

These configuration options are useful if you want to deploy multiple ServerIron ADXs to provide service for the same VIPs or applications, but the network topology cannot ensure that server responses will pass back through the ServerIron ADX.

NOTEThe Direct Server Return (DSR) feature allows you to deploy a single ServerIron ADX in a network where the server responses do not pass back through the ServerIron ADX. Compare the configuration example for SwitchBack with the examples in this chapter to determine which type of configuration is applicable to your network. Refer to “Configuring Direct Server Return” on page 84.

NOTEThe ServerIron ADX does not support Stateless SLB with aliased ports, such as shown in the following configuration: server virtual-name-or-ip v3 10.176.7.23

port dns

port dns stateless

bind dns rs1 7777 real-port dns

Stateless TCP and UDP portsYou can configure a TCP application port to be stateless. When an application port is stateless, the ServerIron ADX does not create session table entries for the port. Configuring an application port to be stateless results in the following benefits:

• The server responses for the application can use alternate paths back to the client. For example, the ServerIron ADX and real servers can be connected through a network that provides multiple return paths to the client. Because the port is stateless, the ServerIron ADX does not assume that the application is unhealthy if the server’s response does not flow back through the ServerIron ADX.

• The ServerIron ADX has more session resources available for application ports that need them. For example, if your server farm provides non-secure web content in addition to secured transaction processing using SSL, you can use the ServerIron ADX to maintain state information for the SSL connections while allowing the HTTP (web) connections to be stateless. The SSL connections flow back through the ServerIron ADX, but the HTTP connections use any available path as determined by a real server’s gateway and other routes back to the client.

205

Stateless TCP and UDP ports3

NOTEThe SwitchBack feature also allows server responses to take paths that do not pass back through the ServerIron ADX. However, SwitchBack still uses session table resources because the ServerIron ADX creates a session table entry for the connection from the client to the real server.

NOTEThe ServerIron ADX supports port translation for stateless SLB. Port translation is useful when clients connect to real servers directly. Without port translation, if a client connects to a real server directly, the ServerIron ADX automatically replaces the source IP address to a VIP. When you configure port translation, the ServerIron ADX overcomes the limitation of performing NAT on all packets initiated from the real server. NAT does not occur because the ServerIron ADX does not match the port number.

NOTEThe ServerIron ADX supports stateless SLB for any TCP and UDP application protocols. For a TCP application, hashing must be enabled on the ServerIron ADX. For a UDP application, you can enable or disable hashing on the ServerIron ADX.

NOTEFTP and TFTP services do not maintain a fixed server port for responses. In such cases stateless mode cannot be used.

How the ServerIron ADX selects a real server for a stateless portThe ServerIron ADX does not use the standard SLB load-balancing methods when selecting a real server for a stateless application port. Instead, the ServerIron ADX uses hash values to select a real server. The ServerIron ADX calculates the hash value for a given client request based on the request’s source IP address and source TCP/UDP port.

The ServerIron ADX has up to 8192 hash buckets (the default is 256) and divides the number of buckets evenly among the real servers. When the ServerIron ADX forwards a client’s request for a stateless application port to the real server that corresponds to the calculated hash value, the ServerIron ADX does not change the source address of the client’s request, but does change the destination address from the requested VIP into the real server’s IP address.

For example, when a ServerIron ADX receives a request for TCP port 80 (HTTP) on VIP (192.168.4.69) from client 10.161.1.88, the ServerIron ADX calculates a hash value based on 10.161.1.88 and 80, then forwards the request to the real server that has the calculated hash value. The request packet is in the following format:

• Source IP: Client’s IP address

• Source application port: Port number selected by client’s application

• Destination IP:Real server’s IP

• Destination application port: Port number requested by client


Stateless TCP and UDP ports 3

If client 10.161.1.88’s Web browser sent the request from TCP port 8080, and the ServerIron ADX’s hash calculation resulted in selecting real server 10.10.10.2, the packet would have the following address values:

• Source IP: 10.161.1.88

• Source application port: 8080

• Destination IP:Real server’s IP 10.10.10.2

• Destination application port: 80

Because the client’s request contains the client’s IP address and application port, the real server can send the packet back to the client along any valid routing path. The request does not need to pass back through the ServerIron ADX that forwarded the request. In fact, the ServerIron ADX that forwards the requests to the transparent VIP does not create session table entries for the requests.

Because the ServerIron ADX does not maintain state information for the requests for stateless application ports, the ServerIron ADX does not care whether the server response for a stateless port passes back through the ServerIron ADX on the way to the client. For a normally configured VIP, the server’s response passes back though the ServerIron ADX. For a transparent VIP, the response does not necessarily pass back through the ServerIron ADX.

NOTEBecause the ServerIron ADX does not create session table entries for requests to the stateless application port, you cannot use ServerIron ADX features that use information from the session table. For example, you cannot use source NAT, port translation, and similar features.

Configuring the stateless hash table sizeYou can configure the size of the stateless hash table as shown in the following:

ServerIronADX(config)#server real R1 10.10.10.1ServerIronADX(config-rs-R1)#server stateless-hash-table-size 1024

Syntax: [no] server stateless-hash-table-size table-size

The table-size variable can be set to any of the following values: 256, 512, 1024, 2048, 4096, or 8192.

The default value is 256.

Configuring a stateless application portTo configure an application port to be stateless, enable the stateless parameter on the port in the virtual server as shown in the following example.

ServerIronADX(config)#server real R1 10.10.10.1ServerIronADX(config-rs-R1)#port httpServerIronADX(config-rs-R1)#exitServerIronADX(config)#server real R2 10.10.11.1ServerIronADX(config-rs-R2)#port httpServerIronADX(config-rs-R2)#exitServerIronADX(config)#server virtual-name-or-ip StatelessHTTP 192.168.4.69ServerIronADX(config-vs-StatelessHTTP)#port http statelessServerIronADX(config-vs-StatelessHTTP)#bind http R1 httpServerIronADX(config-vs-StatelessHTTP)#bind http R2 http

Syntax: [no] port tcp/udp-portnum stateless



The tcp/udp-portnum variable specifies the application port you want to make stateless.

Disabling the stateless SLB hashing algorithm for UDP ports

By default, stateless SLB uses a hashing algorithm to select a real server. The ServerIron ADX calculates a hash value for a given client request based on the request’s source IP address and source TCP/UDP port. The request is sent to a real server corresponding to this hash value.

For UDP connections consisting of one client packet and one server response packet, you can disable the stateless SLB hashing algorithm. When the stateless SLB hashing algorithm is disabled for UDP ports, the ServerIron ADX uses the round-robin load balancing method to select a real server for the request. In this case, the ServerIron ADX load balances UDP packets destined for the VIP without creating a session and without calculating hash values based on UDP port number and source IP address.

DNS is an example of a UDP port where this feature can be used. The advantage of disabling the stateless SLB hashing algorithm is that a new real server can be selected immediately after it is brought up.

For example, to disable the stateless SLB hashing algorithm for the DNS port (UDP port 53), enter commands such as the following:

ServerIronADX(config)#server virtual-name-or-ip Stateless 192.168.4.69ServerIronADX(config-vs-Stateless)#port dns stateless no-hash

Syntax: [no] port udp-portnum stateless no-hash

NOTES: When this command is applied, in some cases it will not take affect. This occurs if the sessions are stuck and it requires you to clear the sessions first and then apply the command, as described in the following.

1. Disable the real server and unbind the VIP.

2. Clear the sessions using the clear server sessions real-server-name command.

3. Apply the stateless no-hash command, bind the real servers to the VIP and enable the real server.

Configuring a port to be both stateless and stateful

You can use the stateless option when configuring an application port on a virtual server to make that port stateless. By default, the port is stateless for both TCP and UDP. You can also specify the protocol for which you want the port to be stateless. For example, you can configure port DNS to be stateless for TCP while remaining stateful for UDP, by entering commands such as the following.

ServerIronADX(config)#server real R1 10.10.10.1ServerIronADX(config-rs-R1)#port httpServerIronADX(config-rs-R1)#exitServerIronADX(config)#server real R2 10.10.11.1ServerIronADX(config-rs-R2)#port httpServerIronADX(config-rs-R2)#exitServerIronADX(config)#server virtual-name-or-ip StatelessDNS 192.168.4.69ServerIronADX(config-vs-StatelessDNS)#port dns stateless tcpServerIronADX(config-vs-StatelessDNS)#bind dns R1 dnsServerIronADX(config-vs-StatelessDNS)#bind dns R2 dns

Syntax: [no] port tcp/udp-port [stateless [tcp | udp] [no-hash]]

The tcp/udp-port variable specifies the application port you want to make stateless.


Stateless TCP and UDP ports 3

The stateless option configures the port to be stateless.

The tcp | udp option restricts stateless operation to the specified protocol (TCP or UDP).

The no-hash option disables the SLB hashing mechanism for the port (and protocol, if specified). When hashing is disabled, the ServerIron uses the round-robin load balancing method to select a real server for each request.

Clearing a virtual port’s stateless hash table

You need to clear the virtual port’s stateless hash table after a specified time interval anytime a binded real server port becomes active (from a non-active state) in order to incorporate the port into the stateless hash table. Use the command as shown in the example:

ServerIronADX(config)#server virtual-name-or-ip StatelessDNS 192.168.4.69ServerIronADX(config-vs-StatelessDNS)#port dns stateless clear-stateless-hash 1000

Syntax: [no] port tcp/udp-port stateless clear-stateless-hash timeout

The timeout variable is specified in number of seconds. Valid range: 0-65535

Fragmentation support in the stateless modeBy default, fragmentation is not supported in the stateless server load balancing mode. Consequently, fragmented packets are dropped. This feature allows you to configure fragmentation support for a specified port in the stateless mode.

This support is necessary in situations where packets exceed the default size and need to be fragmented. For example, DNSSEC adds security headers in the DNS response that make the packet exceed the default packet size (512 Bytes) which causes packet fragmentation. Because of this, DNSSEC messages will be dropped unless Fragmentation support is enabled.

Configuring fragmentation support in the stateless mode

Using this feature, stateless fragmentation support can be provided for a specified port within a VIP. To enable fragmentation support in the stateless mode, use the following command.

ServerIron(config)#server virtual v1 10.10.10.1ServerIron(config-vs-v1)#port dns stateless frag-support

Syntax: [no] port port-name stateless frag-support

The port-name variable specifies the port in the stateless mode that is being enabled for fragmentation.

Feature limitations

• One real server cannot be bound to multiple VIPs even for a different service. This means that, given a real server IP, there is only one VIP that is bound to this real server.

• All packets initiated from real server will be NATed.

• One can however, have an association each for IPv6 and IPv4 address of same server to different VIP (one V6 VIP and one v4 VIP).

• Fragmented pass-through traffic is not supported



• For L7 switching for a different port under the same VIP, Brocade highly recommends using another VIP.

• Connections originating from real server ports other than the ports configured on the ServerIron ADX as real server ports are not supported when fragmented.

Example VIP: 10.11.1.1:80

rs1 10.1.1.1:80 and rs2 10.1.1.2:80

In this configuration, packets from rs1 and rs2 with a source port other than port 80, will exhibit unpredictable behavior when they are fragmented.

In these cases, configure the virtual server as a statefull virtual server.



Chapter

4
Health Checks
Health checks overviewThe ServerIron ADX uses Layer 3, Layer 4, and Layer 7 health checks to verify the availability of real servers and of applications on the real servers.

When you configure a real server, the ServerIron ADX first sends an ARP request for the real server and then sends an IP ping to the server, to verify that the ServerIron ADX can reach the server through the network. The ARP request is sometimes referred to as a Layer 2 health check because the request is for the real server’s hardware layer address.

Later, when you bind the real server to a Virtual IP (VIP) server, the ServerIron ADX sends a Layer 4 or Layer 7 health check to bring up the port you used for the binding. For example, if you bind a real server to a virtual server using port HTTP, the ServerIron ADX sends an HTTP Layer 7 health check to bring up the HTTP port on the real server.

The ServerIron ADX performs the health checks described above by default. In addition, you can enable periodic Layer 4 or Layer 7 keepalive health checks for individual application ports. After successful bringup of an application port when you bind a real server to a virtual server, the ServerIron ADX repeats the Layer 4 or Layer 7 keepalive health check to continually verify the health of the port.

Layer 3 health checksLayer 3 health checks consist of ICMP-based IP pings and ARP requests. When you configure a real server on the ServerIron ADX, the ServerIron ADX sends an ARP request and an IP ping to the real server to verify that the ServerIron ADX can reach the server through the network.

The ServerIron ADX also sends an IP ping to a real server in the following circumstances:

• If the ARP entry for the server times out, the ServerIron ADX uses the IP ping to create a new ARP entry for the server. The ARP request is sometimes referred to as a Layer 2 health check because the request is for the real server’s hardware layer address.

• If the time between the last packet sent to the server and the last packet received from the server increases, the ServerIron ADX uses the IP ping to determine whether the slowed response time indicates loss of the server. If the server responds to the ping, the ServerIron ADX then sends a Layer 4 or Layer 7 health check, depending on whether the port’s application type is known to the ServerIron ADX. The ServerIron ADX sends pings at an interval of 2 seconds apart, and retries unsuccessful pings up to 4 times by default. You can change the ping interval and retries if desired. Refer to “Modifying the ping interval and ping retries” on page 213.

The following Layer 3 health check types are supported:

• ARP Request

• IP Ping

211

Layer 3 health checks4

Table 12 summarizes the Layer 3 health checks.

Disabling Layer 3 health checksBy default, when you add a real server configuration to the ServerIron ADX, the ServerIron ADX uses a Layer 3 health check (IP ping) to determine the server’s reachability. If the real server responds to the ping, the ServerIron ADX changes the server’s state to ACTIVE and begins using the server for client requests.

You can globally disable the Layer 3 health check for local servers or remote servers. You also can disable the Layer 3 health check on individual real servers. When you disable the Layer 3 health check, the ServerIron ADX sends an ARP request for the default gateway and makes the server’s state ACTIVE for as long as the ARP entry remains in the ServerIron ADX’s ARP cache.

To globally disable the Layer 3 health check for all local real servers, enter the following command.

ServerIronADX(config)#server no-real-l3-check

Syntax: [no] server no-real-l3-check

To globally disable Layer 3 health check for all remote real servers or of IP addresses learned through GSLB, enter the following command.

ServerIronADX(config)#server no-remote-l3-check

Syntax: [no] server no-remote-l3-check

NOTEThe server no-remote-l3-check command also disables Layer3 health checks of IP addresses learned through GSLB.

To disable the Layer 3 health check on an individual real server, enter the following command.

ServerIronADX(config-rs-R1)#no-l3-check

Syntax: [no] no-l3-check

This command applies to local real servers and remote real servers.

TABLE 12 Summary of Layer 3 health checks

Type Description When performed

ARP request A standard IP ARP request for the server’s MAC address, which the ServerIron ADX adds to its ARP table.

• When you configure a real server

IP ping A standard ICMP-based IP ping. • When you configure a real server• If the ARP entry ages out• If the time between the last packet

sent to the server and the last packet received from the server increases


Layer 4 health checks 4

Modifying the ping interval and ping retriesThe ServerIron ADX automatically uses a Layer 3 health check, consisting of ICMP echo requests (pings), to check the health of a real server. Ping is enabled by default and cannot be disabled. However, you can modify the ping interval and the number of retries.

To modify the ping interval, enter the following command.

ServerIronADX(config)#server ping-interval 8

Syntax: [no] server ping-interval value

The value variable can be a value from 1 through 10 seconds. The default is 2 seconds.

To modify the number of times the ServerIron ADX will ping a real server before changing the server state to FAILED, enter the following command.

ServerIronADX(config)#server ping-retries 7

Syntax: [no] server ping-retries value

The value variable can be a value from 2 through 10. The default retry value is 4.

Server periodic-ARP enhancement To configure the periodic ARP range, use the following command.

ServerIronADX(config)#server periodic-arp-interval 14400

Syntax: server periodic-arp-interval 10-14400

Layer 4 health checksWhen you bind a real server to a virtual server, the ServerIron ADX performs either a Layer 4 TCP health check, a Layer 4 UDP health check, or a Layer 7 health check to bring up the application port that binds the real and virtual servers. If the application port is not one of the applications that is known to the ServerIron ADX, the ServerIron ADX uses a Layer 4 health check. Otherwise, the ServerIron ADX uses the Layer 7 health check for the known application type.

The Layer 4 health check can be a TCP check or a UDP check:

• TCP health check – The ServerIron ADX checks the TCP port’s health based on a TCP three-way handshake:

- The ServerIron ADX sends a TCP SYN packet to the port on the real server.

- The ServerIron ADX expects the real server to respond with a SYN ACK.

- If the ServerIron ADX receives the SYN ACK, the ServerIron ADX sends a TCP RESET, satisfied that the TCP port is alive.



• UDP health check – The ServerIron ADX sends a UDP packet with garbage (meaningless) data to the UDP port:

- If the server responds with an ICMP “Port Unreachable” message, the ServerIron ADX concludes that the port is not alive.

- If the server does not respond at all, the ServerIron ADX assumes that the port is alive and received the garbage data. Because UDP is a connectionless protocol, the ServerIron ADX and other clients do not expect replies to data sent to a UDP port, so a lack of response indicates a healthy port.

NOTEThe ServerIron ADX assumes that a port is a UDP port unless you configure the port as a TCP port. To configure a port as a TCP port, add a port profile for the port and specify the port type TCP. Refer to “Basing a port’s health on the health of another port” on page 278.

After the ServerIron ADX sends an initial packet (TCP or UDP) to the server to bring the port up, the ServerIron ADX waits one second and then checks for a response from the server. If no response is received during that time, the ServerIron ADX will send another packet. The time at which the ServerIron ADX sends the second packet depends on the number of ports being brought up at that time. The ServerIron ADX will send the second packet after it has sent initial packets to all the other ports being brought up at that time.

By default, the ServerIron ADX does not repeat the Layer 4 health check after bringing up the port when you bind the real server to the virtual server. However, you can enable a periodic keepalive health check for the port. To configure the keepalive health check globally, configure a port profile for the port. You also can enable or disable the keepalive health check on individual real servers.


• TCP

• UDP



Table 13 describes the Layer 4 health check types performance and its description.

Performing Layer 4 UDP keepalive health checks for the DNS portYou can configure the ServerIron ADX to perform Layer 4 UDP keepalive health checks for the DNS port (port 53).

To do this globally for the DNS port on all real servers, enter the following commands:

ServerIronADX(config)#server port dns ServerIronADX(config-port-dns)#udp l4-check-only

NOTEThe l4-check-only command does not apply to the RADIUS protocol.

By default, the ServerIron ADX performs a Layer 4 TCP health check whenever the DNS port on a real server is brought up.

To configure the ServerIron ADX to perform a Layer 4 UDP health check on the DNS port whenever it is brought up, add the no tcp keepalive enable command to the DNS port profile as in the following example:

ServerIronADX(config)#server port dnsServerIronADX(config-port-dns)#no tcp keepalive enable

TABLE 13 Summary of Layer 4 health checks

Type When performed Description

TCP • When you bind a TCP application port on a real server to a TCP application port on a virtual server

• At regular intervals, if keepalive is enabled for the port and the port does not have a Layer 7 health check

The ServerIron ADX attempts to engage in a normal three-way TCP handshake with the port on the real server:• The ServerIron ADX sends a TCP SYN packet to the port

on the real server.• The ServerIron ADX expects the real server to respond

with a SYN ACK.• If the ServerIron ADX receives the SYN ACK, the

ServerIron ADX sends a TCP RESET, satisfied that the TCP port is alive.

UDP • When you bind a UDP application port on a real server to a UDP application port on a virtual server

• At regular intervals, if keepalive is enabled for the port and the port does not have a Layer 7 health check

The ServerIron ADX sends a UDP packet with garbage (meaningless) data to the UDP port. • If the server responds with an ICMP “Port Unreachable”

message, the ServerIron ADX concludes that the port is not alive.

• If the server does not respond at all, the ServerIron ADX assumes that the port is alive and received the garbage data. Since UDP is a connectionless protocol, the ServerIron ADX and other clients do not expect replies to data sent to a UDP port. Thus, lack of a response is a good outcome.



Server response threshold health checkServerIron ADX distributes traffic among real servers based on a dynamic weight value derived from the caculated response time of health check packets. Using the same calculated response times, the ServerIron ADX can perform Layer 4 and Layer 7 health checks.

The ServerIron ADX calculate Layer 4 and Layer 7 response times and compares those with the configured response threshold. If the calculated response time is greater than the configured response threshold, the port is marked DOWN.

The ServerIron ADX calculates Layer 4 and Layer 7 response times differently:

• Layer 4 response times (round trip times) measure the time between the sending of a SYN packet and receiving a SYN ACK packet.

• Layer 7 response times measure the time between the L7 request and the first response packet returned to the server. In the case of an LDAP server, this is the time between a bind request and bind reply. For HTTP servers, this is the time between sending a GET request and the first packet received from server.

The calculated response time is compared to a user-configured response threshold. You can configure a Layer 4 response threshold, a Layer 7 response threshold, or a combined Layer 4 and Layer 7 response threshold.

To define the server response threshold, enter commands such as the following.

ServerIronADX(config)#server real r1 192.168.20.43ServerIronADX(config-rs-r1)#port http response-threshold layer4 200ServerIronADX(config-rs-r1)#port http response-threshold layer7 800

Syntax: [no] response-threshold {layer4|layer7|layer4&7} threshold-value in micro-seconds

The layer4 keyword specifies a Layer 4 response threshold. The layer7 keyword specifies a Layer 7 response threshold. The layer4&7 keyword specifies combined Layer 4 and 7 response threshold.

The threshold-value in microseconds variable accepts an integer value range from 1 to 50000.

Debugging and testingThe show server real command displays health check counters for the port and all servers which you can use when you test or debug response threshold health checks.

Syntax: show real server portnum | port-name



To display configuration information and statistics for the real server configured on the ServerIron ADX, enter the following command:

The fields in bold provides the following information:

• The Bring port down for RTT field displays the number of times the port has been marked down because it has exceeded the configured response threshold. This can be Layer 4, Layer 7, or combined Layer 4 and 7.

• The Current TCP RTT field displays in microseconds the current TCP round trip time. If this value exceeds the configured l4 response threshold, the port is brought down.

ServerIronADX(config)#show server real httpHTTP keepalive statistics: HTTP statistics: URL replace cs: test = 3, fail = 0, malloc fail = 0 GSLB HTTP get ka port = 0, GSLB get ka port = 0 checksum: tested = 1, fail = 0, malloc fail = 0 No free ka port = 0, content match alloc fail = 0 Content match malloc = 0, free = 0 Bring port down = 0, retries = 0 TCP bring up statistics: send buf alloc fail = 0, tcp send fail = 0 Test ka port index null = 0, Tcp conn ka index null = 0 Server close = 0 Suc: ka port index null = 0

test port index null: suc cb = 0, rec cb = 0, fail cb = 0 TCP keepalive statistics: tcb alloc = 0, free = 0, fail = 0 tcb free when state: not active = 0, not bind = 0 suc cb : real port null = 0, ka port null = 0, ka port invalid = 0 rec cb : real port null = 0, ka port null = 0, ka port invalid = 0 fail cb : real port null = 0, ka port null = 0, ka port invalid = 0 conn compl cb : real port null=0, ka port null = 0, ka port invalid =0 tcb mismatch: suc cb = 0, rec cb = 0, fail cb = 0, conn compl cb = 0 real port null = 0, ka port mismatch = 0, ka port invalid = 0 send buf alloc fail = 0, tcp send fail = 0 Server close = 0 Real port not match = 0 TCP statistics: tcp keep alive: close connection 0, remote close 0 tcp connect: connection exist 0, out of tcb 0 tcb: alloc 4, free 0Slot index 4 Real server name = r1, Real port Status = NOT BOUND Slot valid = TRUE IP: 10.10.10.10 Real port index = 7, Real port no = 80 Tcp request = 0, Tcp response = 0 Tcp response timeout = 0, Keepalive Enabled HTTP URL = "HEAD /example1.com" HTTP sent = 0, Received ok = 0 HTTP received error = 0, Receive timeout = 0 wait for response = FALSE, Status code = 0 Server close = 0, Current sent = 0 Bring port down = 0, Total retries = 0 TCP RTT = 0 us, Appl RTT = 0 us Current TCP RTT = 0 us, Current Appl RTT = 0 us Bring port down for RTT= 0 Next slot index = 0



• The Current Appl RTT field displays in microseconds the current application round trip time. If this value exceeds the configured l7 response threshold, the port is brought down.

• The TCP RTT field is a smoothed l4 round trip time that is used by the response time predictor.

• The Appl RTT field is a smoothed l7 round trip time that is used by response time predictor.

Displaying health check related error messages

The server debug hc-error command, when enabled, displays health-check related error messages to the console.

Syntax: server debug hc-error

Layer 7 health checksFor certain TCP and UDP application ports, the ServerIron ADX can send application-specific health checks to determine the health of the application. For example, the ServerIron ADX can send user-configurable HTTP requests to real servers to assess the health of the servers.

When you bind a real server to a virtual server using an application port that is known to the ServerIron ADX, the ServerIron ADX sends a Layer 7 health check to the application on the real server to bring up the application port.

By default, if a client requests a TCP/UDP port that is not available, the ServerIron ADX does not send an ICMP “Destination Unreachable” message to the client. For HTTP traffic, you can configure the ServerIron ADX to send such a message to the client by enabling the ICMP Message feature for HTTP. Refer to “Sending ICMP Port Unreachable or Destination Unreachable messages” on page 150 for details.

You can enable a Layer 7 health check globally by configuring a port profile or locally by enabling the health check on an individual real server. In addition, you can customize some types of Layer 7 health checks for individual real servers. For example, you can specify a URL that the ServerIron ADX should request on a specific real server when sending the Layer 7 HTTP health check to that server.


• “DNS” on page 220

• “FTP” on page 221

• “HTTP” on page 221

• “Scripted (content verification for unknown ports)” on page 222

• “IMAP4” on page 223

• “LDAP” on page 223

• “MMS” on page 224

• “NNTP” on page 224

• “PNM” on page 225

• “POP3” on page 225

• “RADIUS” on page 226



• “RTSP” on page 229

• “SMTP” on page 229

• “SSL” on page 229

• “Telnet” on page 231

Application portsThe ServerIron ADX selects a Layer 4 or Layer 7 health check based on whether the application port is known to the ServerIron ADX. A Layer 4 health check is a TCP or UDP request and is not related to a specific application. A Layer 7 health check is an application-aware health check designed for the specific application. The following application ports are known to the ServerIron ADX. The ServerIron ADX performs Layer 7 health checks for these ports. For other ports, the ServerIron ADX performs a Layer 4 TCP or UDP health check instead.

TCP ports include the following:

• FTP (port 21). Ports 20 and 21 both are FTP ports but on the ServerIron ADX, the name “FTP” corresponds to port 21.

• HTTP (port 80)

• IMAP4 (port 143)

• LDAP (port 389)

• MMS (port 1755)

• NNTP (port 119)

• PNM (port 7070)

• POP3 (port 110)

• RTSP (port 554)

• SMTP (port 25)

• SSL (port 443)

• TELNET (port 23)

UDP ports include the following:

• DNS (port 53)

• RADIUS (port 1812 for authentication, and 1813 for accounting)

• RADIUS-OLD (port 1645), which is used in some older RADIUS implementations instead of port 1812

NOTEYou can add either port 1812 or port 1645 to a given real or virtual server, but you cannot add both ports to the same server.

The keepalive health checks are disabled by default. To enable a keepalive health check for an application port, configure a port profile for the port (which automatically enables the keepalive globally for the port) or enable the keepalive on individual real servers that use the port.



DNSThe ServerIron ADX performs one or both of the following types of DNS health checks:

• Address-based – The ServerIron ADX sends an address request for a specific domain name. If the server successfully responds with the IP address for the domain name, the server passes the health check.

• Zone-based – The ServerIron ADX sends a Source-of-Authority (SOA) request for a specific zone name. If the server is authoritative for the zone and successfully responds to the SOA request, the server passes the health check.

For information on configuring these health checks, refer to “Configuring DNS health check method and values” on page 234.

If you configure both types of DNS health check for a server, the server must successfully respond to both health checks to remain in the server rotation. You enable each type of DNS health check on a global basis and configure them on an individual server basis.

• If the server replies with the requested IP address or zone name, the ServerIron ADX considers the server port to be ACTIVE and marks it as such.

• If the server does not reply with the requested IP address or zone name, the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the requested information, the ServerIron ADX marks the DNS port on the server FAILED and removes the server from the rotation for DNS services.

By default, the health check is non-recursive. If the real server (DNS server) does not successfully reply to the health check, then the DNS port fails the health check. You can enable the real server to perform a recursive lookup for the IP address or zone requested by the health check. In this case, if the real server does not have the requested address or zone, the server can pass the request on to a DNS server with higher authority. Refer to “Enabling recursive DNS health checks” on page 233.

Performed:• Immediately following a successful Layer 4 UDP health check

• At regular intervals, if keepalive is enabled for the port

ConfigurationTo perform a health check on a DNS port, use a configuration such as the following.

Example

ServerIronADX(config-port-dns)#show run | b 53server port 53udp keepalive 15 3tcp keepalive disable

server real rs1 10.2.2.200port dnsport dns keepaliveport dns addr_query "www.brocade.com"

server virtual-name-or-ip test 10.2.2.222sticky-age 60

port dns

bind dns linux dns rs1 dns



!end

NOTEIf the addr_query or zone has a “.” at the end, the ServerIron ADX will return “invalid packet” for Layer 7 DNS health check.

FTPThe ServerIron ADX waits for a message from the server:

• If the server sends a greeting message with status code 220, the ServerIron ADX resets the connection and marks the port ACTIVE.

• If the server does not send a greeting message with status code 220, the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected message, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for FTP service.

Performed:• Immediately following a successful Layer 4 TCP health check


HTTPThe ServerIron ADX supports HTTP status code and content verification health check methods. For information on configuring HTTP health checks, refer to “HTTP” on page 232.

HTTP (status code)

The ServerIron ADX sends HTTP GET or HEAD requests to cache servers (when using TCS) or HTTP servers (when using SLB).

The GET or HEAD request specifies a page (identified by the URL, “Universal Resource Locator”) on the server. By default, the ServerIron ADX sends a HEAD request for the default page, “1.0”.

• If the server responds with an acceptable status code, the ServerIron ADX resets the connection and marks the port ACTIVE. For SLB, the default acceptable status codes for the check are 200–299 and 401. For TCS, the default acceptable status codes are 100–499.

• If the server responds with a different status code, the ServerIron ADX marks the HTTP port FAILED.

• If the server does not respond, the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not respond, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for HTTP service.

NOTEYou can change the status code range for individual servers. If you do so, the defaults are removed and only the status code ranges you specify cause the server to pass the health check.





HTTP (content verification)

The ServerIron ADX sends HTTP GET or HEAD requests to cache servers (when using TCS) or HTTP servers (when using SLB).

The GET or HEAD request specifies a page (identified by the URL) on the server. The ServerIron ADX examines the page and compares the contents of the page to a list of user-defined selection criteria.

Based on the results of this comparison, the ServerIron ADX takes one of the following actions with respect to port 80 (HTTP) on the real server:

• If the page meets the criteria for keeping the port up, then the ServerIron ADX marks the port ACTIVE. This means that the HTTP application has passed the health check.

• If the page meets the criteria for bringing the port down, then the ServerIron ADX marks the port FAILED.

• If the page meets none of the selection criteria, then the ServerIron ADX marks the port either ACTIVE or FAILED according to a user-defined setting.

Refer to “Configuring HTTP content matching lists” on page 266 for information on specifying a page to check and on setting up lists of selection criteria.



Scripted (content verification for unknown ports)After a successful Layer 4 health check, the ServerIron ADX waits for the real server to send back a packet in response.

The ServerIron ADX looks in the response packet for a user-specified ASCII string, defined in a matching list. The ServerIron ADX compares the contents of the string to a list of user-defined selection criteria in the matching list.

Based on the results of this comparison, the ServerIron ADX takes one of the following actions with respect to the port on the real server:

• If the text in the response meets the criteria for keeping the port up, then the ServerIron ADX marks the port ACTIVE.

• If the text in the response meets the criteria for bringing the port down, then the ServerIron ADX marks the port FAILED.

• If the text in the response meets none of the selection criteria, then the ServerIron ADX marks the port either ACTIVE or FAILED according to a user-defined setting.

• If no response is received within the configured interval (the default is five seconds), the ServerIron ADX sends a RST and retries the health check. After the configured number of retries (the default is two retries), if the server still does not respond, the ServerIron ADX marks the server port FAILED.



Refer to “Configuring scripted health checks” on page 270 for more information.



IMAP4The ServerIron ADX waits for a message from the IMAP4 server:

• If the server sends a greeting message that starts with “* OK”, The ServerIron ADX sends a Logout command to the IMAP4 port on the real server, resets the connection, and marks the port ACTIVE.

• If the server does not send a greeting message that starts with “* OK”, the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected message, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for IMAP4 service.



LDAPServerIron ADX supports both anonymous and authenticated bonding with LDAP servers.

With anonymous bonding, ServerIron ADX simply checks the format of the bind response and marks the LDAP port as active so long as the format of the bind response is correct.

Authenticated bonding requires both the configuration of a username and password for authentication and the configuration of a base Distinguished Name (DN) for searching the LDAP directory. With authenticated bonding, ServerIron ADX marks the LDAP port as active only after the completion of a successful authenticated bind and search operation.

For information on configuring LDAP health checks, refer to “LDAP” on page 235.

Anonymous bonding

If a username and password are not configured, the ServerIron ADX sends an anonymous bind request to the LDAP server and waits for a reply. The bind request includes a configurable version number, which can be 2 or 3. The default is 3.

• If the server sends a bind reply with a result code of any status (no error), the ServerIron ADX resets the connection and marks the port ACTIVE.

• If the server does not send a bind reply by the time the LDAP keepalive health check expires, the ServerIron ADX retries the health check for a user-configured number of retries (the default is two). If the server still does not respond, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for LDAP service.



Authenticated bonding

If a username and password are configured, the ServerIron ADX sends an authenticated bind request to the LDAP server that includes three configurable parameters: the version number, the name of the directory object that the client wants to bind to, and information used to authenticate the Distinguished Name (DN).

ServerIron ADX then queries the LDAP directory using a user-configured search.

• If the server sends a bind reply with a result code of any status (no error), the ServerIron ADX resets the connection and marks the port ACTIVE.

• If the result of the query is any error value, the ServerIron ADX marks the server port DOWN and removes the server from the load-balancing rotation for LDAP service.



ServerIron ADX also supports server response threshold health checks for LDAP servers. To learn more see “Server response threshold health check” on page 216.

MMSThe ServerIron ADX sends an intentionally invalid request to the server:

• If the server replies with a packet containing the value "MMS", the ServerIron ADX marks the port ACTIVE.

• If the server does not reply with a packet containing the value "MMS", the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not respond, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for MMS service.

NOTEYou can view the ServerIron ADX’s invalid request in the MMS server log. The log entry has error code 400.



NNTPThe ServerIron ADX waits for a message from the NNTP server:

• If the server sends a greeting message with status code 200 or 201, the ServerIron ADX sends a Quit command to the NNTP port on the real server, then resets the connection by sending a quit and a RESET, one immediately after the other, and marks the port ACTIVE.

• If the server does not send a greeting message with status code 200 or 201, the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected message, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for NNTP service.





PNMThe ServerIron ADX sends a PNM file request that does not have a file name:

• If the server sends a reply containing the value "PNA", the ServerIron ADX marks the port ACTIVE.

• If the server does not send a reply containing the value "PNA", the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected message, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for PNM service.



POP3The ServerIron ADX waits for a message from the POP3 server:

• If the server sends a greeting message that starts with “+ OK”, the ServerIron ADX sends a Quit command to the POP3 port on the real server, then resets the connection by sending a quit and a RESET, one immediately after the other, and marks the port ACTIVE

• If the server does not send a greeting message that starts with “+ OK”, the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected message, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for POP3 service.





RADIUSBy default, the ServerIron ADX performs a RADIUS authentication health check but does not perform a RADIUS accounting health check. The ServerIron ADX sends an authentication request with a user name and password to the RADIUS server. However, the account information does not need to be valid for the server to pass the authentication health check. If you do not enable accounting heath checks, Brocade recommends that you use invalid information to prevent someone from learning account information by observing the ServerIron ADX RADIUS health check. To enable accounting heath check, refer to “Enabling RADIUS accounting health check.”

For additional information of configuring RADIUS health checks, refer to the “RADIUS” on page 234.

NOTEIf the ServerIron ADX is performing health checks for both RADIUS authentication and RADIUS accounting, define a Boolean health check for both the ports.

If the server replies with the result code “ACCEPT” or “REJECT” (or “ACCEPT only”, if required), the ServerIron ADX considers the port to be fine and marks it ACTIVE.

If the server does not reply or the server sends an ICMP “Destination Unreachable” message, the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not reply with “ACCEPT” or ”REJECT” (or “ACCEPT only”), the ServerIron ADX marks the RADIUS port FAILED and removes the server from the rotation for RADIUS services.

It is possible to distinguish between the result code of “ACCEPT” or “REJECT” to determine the health of the RADIUS server by using the server radius-fail-healthcheck-on-access-reject command. For example, a “REJECT” is considered to indicate a health check fail condition.

ServerIronADX(config)#server radius-fail-healthcheck-on-access-reject

NOTEYou can configure a health check either for the well-known RADIUS port number 1812 or port 1645. You cannot configure a health check for both of these ports on the same server.

Performed:• Immediately following a successful Layer 4 UDP health check


Enabling RADIUS accounting health check

By default, RADIUS accounting health check is disabled on the ServerIron ADX. When you enable the accounting health check, the RADIUS health check request is sent to the accounting port of the RADIUS server. The default RADIUS accounting port used for this health check is 1813, unless you define a port in the configuration. You can define this port on a real server, port policy or Boolean health check.

The RADIUS accounting response packet is validated against the accounting response and identifier field.



The following steps describe the validation of the packet and the port state.

1. The ServerIron ADX expects a valid response from the server if the server records and accepts the accounting request. In the case of a failure, the server drops the accounting request packet.

2. The server response is validated against the identifier field in the request packet with the identifier field in the response packet.

3. As part of request accouting packet, the ServerIron ADX sends the authenticator based on the shared key. The server uses the same key on the request packet to generate the authenticator field. If it matches, the server sends the accounting response. Otherwise, the server drops the packet.

4. Depending on the response, the following actions occur:

• If the ServerIron ADX receives a valid response from the server, it marks the port as UP.

• If the ServerIron ADX receives an invalid response from the server, it drops that packet.

• If the ServerIron ADX does not receive any packet within the keepalive time, it performs retries for the accounting request. After the maximum number of retries, if the ServerIron ADX does not receive any response from the server, it marks the port as DOWN.

• If the ServerIron ADX receives any ICMP error, it attempts the maximum number of retries. After reaching the maximum number of retries and receiving an ICMP error, it marks the accounting port as DOWN.

The requirements for RADIUS accounting health check are as follows.

• The shared key is mandatory for RADIUS accounting.

• The following optional parameters present in the RADIUS accouting request, if configured:

- User-Name

- NAS-Identifier

- NAS-Port

Configuring the RADIUS accounting request on a real server portTo configure a port on a real server to send the RADIUS accounting request, use the port radius accounting command in real server configuration mode.

ServerIronADX(config)#server real r1 192.168.20.43ServerIronADX(config-rs-r1)# port radius accounting

Syntax: [no] port radius accounting [port]

The optional port variable defines the real server port. By default, the request is sent on port 1813.

Configuring a RADIUS accounting request on a port policyTo configure a port on a port policy to send the RADIUS accounting request, use the protocol radius accounting command in port policy configuration mode.

ServerIronADX(config)#server port-policy p1ServerIronADX (config-port-policy-p1)# protocol radius accounting

Syntax: [no] protocol radius accounting [port]

The optional port variable defines the port on the port policy. By default, the request is sent on port 1813.



Configuring a RADIUS accounting request on a Boolean health checkTo configure a specified port on a Boolean health check to send the RADIUS accounting request, use the protocol radius accounting command in Boolean health check configuration mode.

ServerIronADX(config)#healthck hh booleanServerIronADX (config-hc-hh)# protocol radius accounting

Syntax: [no] protocol radius accounting [port]

The optional port variable defines the port on the Boolean health check. By default, the request is sent on port 1813.

Displaying RADIUS accounting information on a real serverTo display the number of RADIUS accounting sent and response packets on real servers or a specified real server, use the show server real radius command.

ServerIronADX # show server real radius rs1

Slot index 1 Real server name = rs1, Real port Status = FAILED Slot valid = TRUE IP: 19.1.1.99 Real port index = 2, Real port no = 1812 Keepalive Enabled, Current ID = 57 RADIUS key = "FOUndry123" RADIUS Accounting sent = 57, Accounting Response = 52 Last received code = 5, Last Received id = 52 RADIUS ID not match = 0, Invalid opcode = 0 RADIUS msg recv: Not wait for response = 0 RADIUS response timeout = 4, Current sent = 1 RADIUS wait for response = TRUE, Return code = 0 RADIUS bring port down = 2, Total retries = 0 Next slot index = 0

Syntax: show server real radius [real_server]

The optional real_server variable is the name of a specific real server.



RTSPThe ServerIron ADX sends a standard RTSP option packet, using sequence number 1:

• If the server responds with an acceptable status code, the ServerIron ADX resets the connection and marks the port ACTIVE. For SLB, the default acceptable status codes for the check are 200–299 and 401.

• If the server responds with a different status code, the ServerIron ADX marks the port FAILED.

• If the server does not respond, the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not respond, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for RTSP service.



SMTPThe ServerIron ADX waits for a message from the SMTP server:

• If the server sends a greeting message with status code 220, the ServerIron ADX sends a Quit command to the SMTP port on the real server, then resets the connection by sending a quit and a RESET, one immediately after the other, and marks the port ACTIVE.

• If the server does not send a greeting message with status code 220, the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected message, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for SMTP service.



SSLThe ServerIron ADX supports the complete and simple SSL health checking methods. For information on their supported ciphers and configuration, refer to the “Simple and complete SSL health checks” on page 237.

SSL (complete)

The ServerIron ADX initiates an SSL connection with the server on TCP port 443, a secure link is negotiated, and encrypted data is transferred across it.

NOTESSL Layer 7 health check supports a maximum RSA key bit length of 4096. An RSA key bit length of 8192 is not supported.



After the SSL connection is established, the ServerIron ADX sends the SSL server an HTTP GET or HEAD request. The GET or HEAD request specifies a page containing the URL of a page on the server. By default, the ServerIron ADX sends a HEAD request for the default page, “1.0”, although this can be changed with the port ssl url command:

• If the server responds with an acceptable status code, the ServerIron ADX resets the connection and marks the port ACTIVE.

• If the server does not respond, the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not respond, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for SSL service.



It is possible to assign an HTTP content verification health check to the real server for the page returned by “port ssl url”. The ServerIron ADX examines the text in an HTML file sent by a real server in response to an HTTP keepalive request. The ServerIron ADX searches the text in the HTML file for user-specified selection criteria and determines whether the SSL port on the real server is alive based on what it finds. The selection criteria used in HTTP content verification is contained in a matching list that is attached to one or more real servers.

NOTEReference the topic on “Using SSL health checks in a health check policy” on page 260 and the “Content match for HTTP” on page 266 for more information.

SSL (simple)

The ServerIron ADX sends an SSL client hello with the SSL SID set to 0:

• If the server responds, then the ServerIron ADX resets the connection and marks the port ACTIVE.

• If the server does not respond, the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not respond, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for SSL service.





TelnetThe ServerIron ADX waits for a message from the Telnet server:

• If the server sends a command string that starts with the IAC escape characters (“FF”), the ServerIron ADX resets the connection and marks the port ACTIVE.

• If the server does not send a command that starts with the IAC escape character, the ServerIron ADX retries the health check up to the number of times configured (the default is two retries). If the server still does not send the expected escape character, the ServerIron ADX marks the server port FAILED and removes the server from the load-balancing rotation for Telnet service.



Configuring port-specific settings

Layer 7 health checks

You can configure the following Layer 7 health check parameters on a real server basis:

• Keepalive health check state (enabled or disabled)

• HTTP keepalive method, values, and valid status codes

• HTTP content matching lists for HTTP content verification health checks

• Scripted health checks (content verification health checks for unknown ports)

• DNS keepalive method and values (zone-based or addressed-based check and the zone or domain name)

• RADIUS keepalive values (user name, password, and encryption key)

• LDAP version (2 or 3)

NOTEThe ServerIron ADX uses its own management IP address or a source IP address configured on the ServerIron ADX as the source IP address in the health check packets (as opposed to a virtual IP address). If the real servers are in the same subnet as the ServerIron ADX, then the health checks can use the ServerIron ADX’s management IP address. Otherwise, the health checks use a source IP address. Refer to “Web hosting with ServerIron ADX and real servers in different subnets” on page 534.

Enabling Layer 7 health check

All Layer 7 health checks are disabled by default. You can enable a health check globally or locally.

NOTEThe ServerIron ADX considers a Layer 7 health check to be disabled only if the health check is disabled on both the global and local levels. If the health check is enabled globally, locally, or both, the ServerIron ADX considers the health check to be enabled. Refer to “Configuring a port profile” on page 244.



To locally enable a Layer 7 health check, enter a command such as the following at the real server level of the CLI.

ServerIronADX(config-rs-jet)#port dns keepalive

Syntax: [no] port port keepalive

If you use the no port command, you are locally disabling the health check. The health checks are locally disabled by default.

The port variable can have one of the following values:

• dns (port 53)

• ftp (port 21). Ports 20 and 21 both are FTP ports but in the ServerIron ADX, the name “ftp” corresponds to port 21.

• http (port 80)

• imap4 (port 143)

• ldap (port 389)

• nntp (port 119)

• ntp (port 123)

• pop2 (port 109)

• pop3 (port 110)

• radius (UDP port 1812)

• radius-old (UDP port 1645, which is used in some older RADIUS implementations instead of port 1812)

• smtp (port 25)

• snmp (port 161)

• ssl (port 443)

• telnet (port 23)

• tftp (port 69)

• number

NOTESpecify the port number if the port is not one of the well-known names listed above.

HTTP

Changing HTTP keepalive method, value, and status codes

The ServerIron ADX supports two kinds of HTTP health checks:

• HTTP status code health checks look at the status code returned in HTTP responses to keepalive requests.

• HTTP content verification health checks look at the actual HTML contained in HTTP responses to keepalive requests.

The default URL page for HTTP keepalive requests used in HTTP health checks is “HEAD /1.0”. You can change the URL that the ServerIron ADX requests on a real server basis.



NOTEFor HTTP content verification health checks, you might want to change the default URL page for HTTP keepalive requests URL page, since a request for “HEAD /1.0” would not return a response containing HTML for content verification. You can specify a GET request for a page containing text that can be searched and verified. Refer to “Configuring HTTP content matching lists” on page 266 for more information.

To configure the HTTP keepalive request to send a GET request for “sales.html”, enter the following commands.

ServerIronADX(config)#server real zip 10.96.3.251ServerIronADX(config-rs-zip)#port http url "GET /sales.html"ServerIronADX(config-rs-zip)#exit

ServerIronADX(config)#server virtual-name-or-ip shoosh 10.96.4.250ServerIronADX(config-vs-shoosh)#port httpServerIronADX(config-vs-shoosh)#bind http zip httpServerIronADX(config-vs-shoosh)#exit

Syntax: port http url “[GET | HEAD] [/] URL-page-name”

GET or HEAD is an optional parameter that specifies the request type. By default, HTTP keepalive uses HEAD to retrieve the URL page. You can override the default and configure the ServerIron ADX to use GET to retrieve the URL page.

The slash (/) is an optional parameter. If you do not set the GET or HEAD parameter, and the slash is not in the configured URL page, then ServerIron ADX automatically inserts a slash before retrieving the URL page.

To change the HTTP status codes that the ServerIron ADX considers normal (not indicative of a failure of the HTTP service), enter the following command.

ServerIronADX(config-rs-zip)#port http status-code 200 201 300 302

Syntax: port http status-code range [range[range[range]]]

The command in the example specifies two ranges (200–201 and 300–302). You can specify up to four ranges (total of eight values). To specify a single message code for a range, enter the code twice. For example to specify 200 only, enter the port http status-code 200 200 command.

NOTEWhen you change the status code ranges, the defaults are removed. As a result, you must specify all the valid ranges, even if a range also is within the default ranges. For example, if you still want codes 200–299 to be valid, you must specify them.

DNS

Enabling recursive DNS health checks

By default, a Layer 7 health check for a DNS port sends the query only to the real server (DNS server). If the DNS server does not reply with the IP address or zone name requested by the health check, the port fails the health check.



You can enable the real server to perform a recursive lookup for the IP address or zone requested by the health check. In this case, if the real server does not have the requested address or zone, the server can pass the request on to a DNS server with higher authority. The real server can repeat this process until either a DNS server with higher authority successfully replies to the health check, or the server with the highest authority is unable to successfully reply to the request.

To enable recursive DNS health checks globally at the port profile level for the DNS port, enter commands such as the following.

ServerIronADX(config)#server port dns ServerIronADX(config-port-dns)#allow-recursive-search

Syntax: [no] allow-recursive-search

NOTEThis feature applies to Boolean health checks in addition to standard (non-Boolean) health checks.

NOTEYou can enable this feature only on the well-known DNS port (53).

Configuring DNS health check method and values

The keepalive time and number of retries are global parameters. However, you configure the DNS health checking methods and values on an individual server basis. You can set the following types of DNS health checks (none configured by default):

• Address-based – The ServerIron ADX sends an address request for a specific domain name. If the server successfully responds with the IP address for the domain name, the server passes the health check.

• Zone-based – The ServerIron ADX sends a Source-of-Authority (SOA) request for a specific zone name. If the server is authoritative for the zone and successfully responds to the SOA request, the server passes the health check.

To configure the domain name for address-based DNS health checking, enter the following command.

ServerIronADX(config-rs-zip)#port dns addr_query "example2.com"

Syntax: [no] port dns addr_query "name"

To configure the zone name for zone-based DNS health checking, enter the following command.

ServerIronADX(config-rs-zip)#port dns zone example2.com

Syntax: [no] port dns zone zone-name

RADIUS

Configuring RADIUS authentication health check values

You can define the RADIUS parameters that the ServerIron ADX sends to a RADIUS application port during the Layer 7 health check.

The RADIUS health check requests a specific user name, password, and authentication key from the RADIUS server. To specify these values, use one of the following methods.



To configure the parameters for a RADIUS health check, enter commands such as the following at the real server level of the CLI.

ServerIronADX(config-rs-rocket)#port radius username evilServerIronADX(config-rs-rocket)#port radius password woodyServerIronADX(config-rs-rocket)#port radius key laser

Syntax: [no] port radius username string

Syntax: [no] port radius password string

Syntax: [no] port radius key string

Dropping failed RADIUS authentication health checks

With a valid response from a RADIUS server (that is, user authentication pass or fail), the ServerIron ADX marks the RADIUS health check as passed. However, this behavior might not be desired in some cases. The following enhancement lets the ServerIron ADX mark the RADIUS health check as FAIL if authentication is received as (PW_ACCESS_REJECT).

ServerIronADX(config-rs-rocket)#server radius-fail-healthcheck-on-access-reject

Syntax: [no] server radius-fail-healthcheck-on-access-reject

LDAP

Configuring Usernames for Authenticated LDAP Bonding

Authenticated bonding with an LDAP server requires the configuration of a username and password that are sent as parameters in the bind request.

To define the username the ServerIron ADX will use to create an authenticated bind with an LDAP port on a real server, enter commands such as the following at the real port level of the CLI.

ServerIronADX(config)#server real r1 192.168.20.43ServerIronADX(config-rs-r1)#port ldap username “cn=Directory Manager”

Syntax: [no] port {ldap | ldaps | port-num} username name

The name variable specifies the name of the Directory object that the ServerIron ADX will bind as; it is a character string that cannot exceed 128 characters.

Configuring Passwords for Authenticated LDAP Bonding

To define the password the ServerIron ADX will use to create an authenticated bind with an LDAP port on a real server, enter commands such as the following at the real port level of the CLI.

ServerIronADX(config)#server real r1 192.168.20.43ServerIronADX(config-rs-r1)#port ldap password “brocade123”

Syntax: [no] port {ldap | ldaps | port-num} password string

The string variable specifies the password for the Directory object that the ServerIron ADX binds as; it is a character string that cannot exceed 64 characters.



Configuring Base Distinguished Names for Authenticated LDAP Bonding

To configure the base Distinguished Name (DN) used to query the LDAP directory, enter commands such as the following at the real port level of the CLI.

ServerIronADX(config)#server real r1 192.168.20.43ServerIronADX(config-rs-r1)#port ldap search-base-dn “ou=groups,dc=brocade,dc=com”

Syntax: [no] port {ldap | ldaps } search-base-dn distinguished-name

The distinguished-name is a character string that cannot exceed 256 characters.

LDAP over SSL

The ServerIron ADX can perform LDAP health checks using a Secure Sockets Layer (SSL) connection on TCP port 636.

The LDAP over SSL (LDAPS) health check procedure works as follows:

The ServerIron ADX initiates an SSL connection with the server on TCP port 636, a secure link is negotiated, and encrypted data is transferred across the link. After the SSL connection is established, the ServerIron ADX sends a bind request to the LDAPS server and waits for a reply. The bind request includes a configurable version number, either 2 or 3 (by default, version 3).

• If the LDAPS server sends a bind reply with a result code of any status (no error), the ServerIron ADX resets the connection and marks the port ACTIVE.

• If the LDAPS server does not send a bind reply by the time the LDAPS keepalive interval expires, the ServerIron ADX retries the health check up to the number of times configured (by default, two retries). If the LDAPS server still does not respond, the ServerIron ADX marks the server port FAILED and removes the LDAPS server from the load-balancing rotation for LDAPS service.

You can configure standard (non-Boolean) LDAPS health checks in addition to Boolean LDAPS health checks. Health checking commands available for other TCP ports are also available for the LDAPS port.

Configuring Non-boolean LDAP health checksTo configure a standard health check for the port ldaps command on real server r1, enter the following commands.

ServerIronADX(config)#server port ldapsServerIronADX(config-port-ldaps)#tcp keepalive enableServerIronADX(config-port-ldaps)#exitServerIronADX(config)#server real r1 10.10.1.101ServerIronADX(config-rs-r1)#port ldapsServerIronADX(config-rs-r1)#exit

If the no-fast-bringup command is not configured for the LDAPS port, if the l4-check-only command is configured for the LDAPS port, or if the keepalive health check for the LDAPS port is disabled, the ServerIron ADX does not establish a secure connection when performing a health check on port 636. Instead, the ServerIron ADX establishes a regular TCP connection on port 636 and sends a TCP RESET, using the same method as the LDAP health check.



Configuring Boolean LDAP health checksTo configure a Boolean LDAPS health check, enter commands such as the following.

ServerIronADX(config)#healthck check1 tcpServerIronADX(config-hc-check1)#dest-ip 10.10.1.101ServerIronADX(config-hc-check1)#port ldapsServerIronADX(config-hc-check1)#protocol ldapsServerIronADX(config-hc-check1)#l7-check

A Layer 7 health check must be configured in order for the ServerIron ADX to establish a secure connection on the LDAPS port. If only a Layer 4 health check is configured, then the ServerIron ADX establishes a regular TCP connection on port 636.

Simple and complete SSL health checksThe ServerIron ADX supports two kinds of SSL health checking methods:

• The simple method sends the server an SSL client hello with the SSL SID set to 0. If the server responds, then the server passes the health check. The ServerIron ADX then resets the connection and marks the SSL port ACTIVE.

• The complete method negotiates an SSL connection and sends a GET or HEAD request to the server once the connection is established. The GET or HEAD request specifies a page containing the URL of a page on the server. If the server responds with an acceptable status code, the ServerIron ADX resets the connection and marks the port ACTIVE.

The simple and complete SSL health checks use cipher suites as part of the SSL Hello sent to the SSL server, and the server choses the cipher as part of the Hello sent to the ServerIron ADX SSL client. If the complete SSL method is enabled on the ServerIron ADX, the cipher choosen by the SSL server is used in additional SSL communications for encryption.

Table 14 lists the cipher suites for the SSL health check methods.

TABLE 14 Cipher suites for simple and complete SSL health check methods

Cipher suite SSL health check method

TLS_RSA_WITH_AES_256_CBC_SHA Simple and complete

TLS_RSA_WITH_AES_128_CBC_SHA Simple and complete

TLS_DHE_RSA_WITH_3DES_EDE_CBC_SHA Simple

TLS_DHE_DSS_WITH_3DES_EDE_CBC_SHA Simple

TLS_RSA_WITH_3DES_EDE_CBC_SHA Simple and complete

TLS_RSA_WITH_IDEA_CBC_SHA Simple and complete

TLS_RSA_WITH_RC4_128_SHA Simple and complete

TLS_RSA_WITH_RC4_128_MD5 Simple and complete

TLS_DHE_RSA_WITH_DES_CBC_SHA Simple

TLS_DHE_DSS_WITH_DES_CBC_SHA Simple

TLS_RSA_WITH_DES_CBC_SHA Simple and complete

SSL2_CK_3DES Simple and complete

SSL2_CK_IDEA Simple and complete

SSL2_CK_RC2 Simple and complete



Configuring SSL health checks

To configure the ServerIron ADX to use the simple SSL health check, enter the following command.

ServerIronADX(config)#server use-simple-ssl-health-check

To use the complete SSL health check, enter the no server use-simple-ssl-health-check command.

ServerIronADX(config)#no server use-simple-ssl-health-check

NOTEWhen you configure complete SSL health check on the ServerIron ADX and the server response is in small TCP segment packets of 5 to 50 bytes, flapping occurs and the ServerIron ADX displays the following error messages:SSL interface: ssl_read_data return error !!!

SSL read data: can't find key ???

Syntax: [no] server use-simple-ssl-health-check

Error messages

The following error messages are related to an SSL health check after the ServerIron ADX receives SSL data and cannot find the key to decrypt the data. The key is missing possibly due to a time out.

ssl_receive_data but tcb->ssl is nullSSL cleanup: can't find key ???SSL interface: ssl_read_data return error !!!ssl_receive_data but tcb->ssl is nullSSL cleanup: can't find key ???SSL interface: ssl_read_data return error !!!ssl_receive_data but tcb->ssl is nullSSL cleanup: can't find key ???SSL interface: ssl_read_data return error !!!

The ServerIron ADX normally stops processing the rest of the data and releases the SSL control block data structure. However, when the ServerIron ADX does not do that, the ServerIron ADX finds the SSL data structure is null and prints these messages.



SSL2_CK_DES Simple and complete

TLS_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA Simple

TLS_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA Simple

TLS_RSA_EXPORT_WITH_DES40_CBC_SHA Simple and complete

TLS_RSA_EXPORT_WITH_RC2_CBC_40_MD5 Simple and complete

TLS_RSA_EXPORT_WITH_RC4_40_MD5 Simple and complete

SSL2_CK_RC2_EXPORT40 Simple and complete

SSL2_CK_RC4_EXPORT40 Simple and complete

TABLE 14 Cipher suites for simple and complete SSL health check methods (Continued)

Cipher suite SSL health check method



Layer 7 health check for an unknown portYou can use Layer 7 health check parameters for the following known ports to check the health of unknown ports:

• TCP ports:

• FTP (port 21)


• LDAP (port 389)

• POP3 (port 110)

• SMTP (port 25)

• Telnet (port 23)

• UDP ports:

• DNS (port 53)

Configuring an unknown TCP port to use Layer 7 TCP health checks

You can use the ServerIron ADX’s Layer 7 health check mechanism for the following TCP applications on any TCP port number:

• FTP (port 21)


• LDAP (port 389)

• POP3 (port 110)

• SMTP (port 25)

• Telnet (port 23)

The health check mechanisms for these ports are described in “Health checks overview” on page 211.

To configure an unknown TCP port to use the Layer 7 health check for one of the applications listed above, enter commands such as the following.

ServerIronADX(config)#server port 999ServerIronADX(config-port-999)#tcp keepalive protocol smtp

These commands configure port profile parameters for port 999. The second command in the example makes the port a TCP port and assigns the SMTP Layer 7 health check to the port.

Syntax: [no] server port TCP-portnum

Syntax: [no] tcp keepalive protocol TCP-port

The protocol TCP-port parameters specify the type of Layer 7 health you want to use for the port. You can specify one of the following:

• ftp or 21

• imap4 or 143

• ldap or 389

• pop3 or 110


Server and application port states4

• smtp or 25

• telnet or 23

Configuring an unknown UDP port to use a Layer 7 health check

The ServerIron ADX can perform Layer 7 health checks on the DNS port (UDP port 53).

To configure an unknown UDP port to use the DNS Layer 7 health check:

• Configure the Layer 7 health check on the DNS port (53). For configuration information, refer to “Configuring DNS health check method and values” on page 234. The unknown port uses the same health check parameters as the ones you configure for the DNS port. For example, if you configure an address-based DNS health check for a specific domain name, the ServerIron ADX requests the same domain name when checking the health of the unknown port.

• Create a port profile for the unknown port and specify dns or 53 as the well-known port whose Layer 7 health check you want to use.

To configure an unknown port to use a Layer 7 health check, enter commands such as the following.

ServerIronADX(config)#server port 999ServerIronADX(config-port-999)#udp keepalive protocol dns

Syntax: server port UDP-portnum

Syntax: udp keepalive protocol UDP-portnum

The protocol UDP-port parameters specify the type of Layer 7 health you want to use for the port. You can specify dns or 53.

Server and application port states

Server statesThe server states only concern up to Layer 3. They do not deal with Layers 4 or Layer 7. In Table 15, Layer 2 reachability refers to ARPs, a Layer 2 query for Layer 3 information. Layer 3 reachability refers to ICMP echo requests and replies, or pings.

NOTELayer 4 refers to making a TCP connection to a port. Layer 7 refers to making an HTTP request and getting an HTTP reply.

TABLE 15 Server states

State Description

ENB:enabled There is no link to the real server. The real server is configured on the ServerIron ADX but is not physically connected to the ServerIron ADX.

FAL:failed The real server has failed to respond to repeated Layer 3 health checks (IP pings). Typically, a real server changes to the FAILED state from the SUSPECT state.


Server and application port states 4

Application port statesTable 16 lists the application port states.

TST:testing A real server will go to "Testing" if it is reachable at Layer 2 but not at Layer 3. When you first add a real server, the ServerIron ADX will first try to ARP it. While it is ARPing, the server state will read "State: Enabled". After the real server replies to the ARP, the ServerIron ADX will normally send one ICMP echo request. After it gets the ARP reply and before it gets the ICMP echo reply, the ServerIron ADX will show the real server state as Testing. If you have a firewall application on the real server so that it responds to ARP queries but not to ICMP pings, then the real server will show as "Testing" indefinitely.Use the show server real command to display detailed state information. The show server bind command is more concise, though it focuses on port status.

SUS:suspect The ServerIron ADX associates a time stamp with each packet sent to and received from the real servers. If the time gap between the last packet received from the server and the last packet sent to the server grows to 3 or 4 seconds, the ServerIron ADX sends a ping (Layer 3 health check) to the server. If the server does not respond within the ping interval (a configurable parameter), the ServerIron ADX changes the state to SUSPECT and resends the ping, up to the number of retries specified by the ping retries parameter (also configurable). If the server still does not respond after all the retries, the state changes to FAILED. If the server does respond, the state changes to ACTIVE.

GDN:grace-dn The server gracefully shut down. Refer to server force-delete command under the “Enabling force-delete” section.

ACT:active A real server will go to active as long as it is reachable at Layer 2 and Layer 3, regardless of whether its ports are bound to anything, or whether its ports pass tests.After receiving the first ping reply, the ServerIron ADX normally switches to periodic ARPs. If you enable the server l3-health-check command globally, then the ServerIron ADX switches to using periodic pings instead. The real server still shows the state active. If you enter the no server l3-health-check command globally, then the ServerIron ADX will switch back to ARP. After the first ping succeeds, if you do not have Layer 3 health checks enabled, you can add an ICMP blocking ACL on the real server, and the system will still display "Active". If you re-add the server l3-health-check command, then the real server state will change from Active to Suspect and then Failed. This behavior takes place before any ports have been bound to a virtual server. All these states on a real server have nothing to do with Layer 4 or Layer 7.

UNB:unbind Used for ports that have not been bound to a virtual server.

AWU:await-unbindAWD: await-shutdown

Both can occur when you're trying to unbind or delete ports. You might not even see them in anything but a live environment. After you remove real servers from a virtual server or delete virtual servers or unbind ports, normally the ServerIron ADX or stackable waits until connections in progress finish their business.

TABLE 16 Application port states

State Description

ENABLED There is no link to the server. The server is configured on the ServerIron ADX but is not connected to the ServerIron ADX. (This is the same as the ENABLED server state.)

FAILED The application has failed to respond to repeated Layer 4 or (if applicable) Layer 7 health checks. Typically, an application changes to the FAILED state from the SUSPECT state. Note that if a application does not pass the Layer 4 health check, the ServerIron ADX does not waste resources on the Layer 7 health check, because the application clearly is not available. When an application enters the FAILED state, the state of the real server itself moves to the TEST state while the ServerIron ADX continually tries to reach the failed application.

TABLE 15 Server states (Continued)

State Description


Server and application port states4

Displaying real server state information

To display real server information, enter the following command at any level of the CLI.

Information about the remaining real servers has been omitted for brevity.

Syntax: show server real

The state information lists the state of the server itself first. Then the states of each of the application ports configured on the server are displayed.

In this example, the server itself is enabled. The HTTP port is also enabled, but the “default” port (a port the ServerIron ADX automatically configures on all the real and virtual servers) is unbound (unbnd). These states are typical of a ServerIron ADX that is configured for deployment but has not been connected to the real servers.

The information under the row for the HTTP application shows settings for the Layer 7 health checks for the port. For information about HTTP health checks and other configurable Layer 7 health check parameters, refer to “Layer 7 health checks” on page 231.

TEST The server is still reachable at Layer 3, but the application has failed to respond to its Layer 4 (or if applicable, Layer 7) health check.

SUSPECT The ServerIron ADX associates a time stamp with each packet sent to and received from the real servers. If the time gap between the last packet received from the server and the last packet sent to the server grows to 3 or 4 seconds, the ServerIron ADX sends a Layer 4 health check to the service. (If applicable, and if the server passes the Layer 4 health check, the ServerIron ADX then sends a Layer 7 health check to the application.) If the application does not respond within a specified interval, the ServerIron ADX changes the state to SUSPECT and resends the Layer 4 (and if applicable, Layer 7) health check up to a specific number of retries. If the application still does not respond after all the retries, the state changes to FAILED and the server state changes to TEST. If the application does respond, the application state changes to ACTIVE.

GRACE_DN The forced-shutdown option has been used to gracefully shut the server down.

ACTIVE The application has passed its Layer 4 (and if applicable, Layer 7) health check.

UNBND The application is configured on the real server but is not yet bound to a virtual server.

TABLE 16 Application port states (Continued)

State Description

ServerIronADX(config)#show server realReal Servers Info

Server State - 1:enabled, 2:failed, 3:test, 4:suspect, 5:grace_dn, 6:activeName:rs1 IP: 10.95.7.1:1 State:1 Wt:1 Max-conn:1000000Src-nat (cfg:op) = 0: 0 Dest-nat-(cfg:op) = 0: 0Remote server: No Dynamic: No :Mac-info: ffffPort State Ms CurConn TotConns Rx-pkts Tx-pkts Rx-octet Tx-octet Reashttp enabled 0 0 0 0 0 0 0 0 Keepalive(G/L:Off/Off):Off Status Code(s): default (200-299, 401) HTTP URL: "HEAD /"defaulunbnd 0 0 0 0 0 0 0 0Server Total 0 0 0 0 0 0 0


Port profiles and attributes 4

Displaying virtual server state information

To display virtual server information, enter the following command at any level of the CLI.

Information about the remaining virtual servers has been omitted for brevity.

Syntax: show server virtual

In this example, the virtual server and the application ports configured on the server are enabled, indicating that the server and the application ports are configured on the ServerIron ADX but the ServerIron ADX is not connected to the real servers bound to this virtual server. Refer to “Displaying real server state information” on page 242 for descriptions of the server and application states.

NOTEThe number following “state” in the “Sym” row indicates the Symmetric Active-Standby HA state of this VIP.

Alias port state and master port state definitions

When a virtual port is bound on an alias port, the alias port contains two states: its own alias port state and the state of the master port. The master port state refers to the health check status of its master port.

For example, in the following server binding information, the first state (Active) indicates the alias port state and the second state (Failed) indicates master port state.

Bind infoVirtual server:vs1 Status:enabled IP: 198.51.100.1

http------>rs1: 192.0.2.1, 8080 (Active-Failed)

Port profiles and attributesA port profile is a set of attributes that globally defines an application port. Once defined, the port has the same attributes on all the real and virtual servers that use the port. Port profiles are useful if you want to globally change the attributes of a port known to the ServerIron ADX (refer to the list in “Layer 7 health checks” on page 231) or you want to globally define a port that is not known to the ServerIron ADX. You also can specify or change port attributes locally, on the real server and virtual server configuration levels.

If you want to enable the keepalive health check for an application port, you must configure a port profile for the port.

ServerIronADX(config)#show server virtual

Virtual Servers InfoServer Name: v100 IP : 10.157.23.100 : 4Status: enabled Predictor: least-conn TotConn: 4233Dynamic: No HTTP redirect: disabledSym: group = 1 state = 5 priority = 2 keep = 0 Activates = 4, Inactive= 3Port State Sticky Concur CurConn TotConn PeakConnhttp enabled NO NO 0 4233 39default enabled NO NO 0 0 0


Port profiles and attributes4

Configuring a port profileFor an application port not known to the ServerIron ADX, the ServerIron ADX assumes that it is a UDP port. In addition, the ServerIron ADX does not perform keepalive health checks for it. You can configure a port profile for the port and specify whether the port is TCP or UDP, in addition to setting keepalive health check parameters for the port.

Even for ports known to the ServerIron ADX, you must configure a profile for the port to globally configure the port parameters and to configure the keepalive health check. After you add the port by indicating whether it is a TCP or UDP port, the ServerIron ADX automatically enables the keepalive health check for the port.

NOTEEnabling or disabling a keepalive health check does not affect the health check the ServerIron ADX sends when you bind a real server to a virtual server using the application port. The keepalive health check state also does not affect the health checks the ServerIron ADX sends if the server’s response time slows.

The keepalive interval and retry values for each type of TCP/UDP health check are global parameters. For example, if you change the number of retries for the HTTP health check (TCP port 80), the change applies to all instances of port 80 on all the real servers configured on the ServerIron ADX.

As shown in the Table 17, after a keepalive health check is enabled, to disable it you must do so both globally and locally. If you want to enable keepalive health checks only on specific real servers (locally), you can easily do so by making sure the health checks are disabled globally, then enabling them on individual real servers.

To enable or disable a keepalive health check globally, use one of the following methods. To enable or disable a keepalive health check locally, refer to “Enabling Layer 7 health check” on page 231.

NOTEDNS, HTTP, and RADIUS health checks use additional parameters, which you can configure using separate commands. Refer to “Changing HTTP keepalive method, value, and status codes” on page 232, “Configuring DNS health check method and values” on page 234, or “Configuring RADIUS authentication health check values” on page 234.

NOTEWhen health checks are enabled for the ports on the VIPs in a host range, the ServerIron ADX checks the health of the applications on the base IP address only. The ServerIron ADX assumes that the health of an application is the same for all the VIPs within the host range.

TABLE 17 Keepalive health check states

State

Global (entire ServerIron ADX)

Local (specific real server) Effect

Disabled Disabled Health check is disabled

Disabled Enabled Health check is enabled

Enabled Disabled Health check is enabled

Enabled Enabled Health check is enabled



Adding a port and specifying its type

By adding a port, you also automatically enable periodic Layer 4 (and Layer 7, if applicable) keepalive health checks for the port. If you do not specify the port type (TCP or UDP), the ServerIron ADX assumes the port type is UDP.

To add a port and specify that it is a TCP port, enter commands such as the following.

ServerIronADX(config)#server port 8080ServerIronADX(config-port-8080)#tcp

Syntax: server port TCP/UDP-portnum

Syntax: tcp | udp [keepalive [disable | enable]]

Changing a port’s keepalive parameters

To change a port’s keepalive state, enter a command such as the following.

ServerIronADX(config-port-8080)#tcp keepalive disable

To change a port’s keepalive interval and retries, enter a command such as the following.

ServerIronADX(config-port-80)#tcp keepalive 15 5

Syntax: tcp | udp keepalive [interval-in-seconds retries]

You can specify from 1 through 120 seconds for the interval-in-seconds variable. You can specify from 1 through 5 for the retries variable.

Configuring port profile attributesTable 18 lists the port attributes you can configure at the port profile level.

TABLE 18 Port profile attributes

Attribute Description

Port type (TCP or UDP)

This attribute applies only to ports for which the ServerIron ADX does not already know the type. For example, if a real server uses port 8080 for HTTP (a TCP port), you can globally identify 8080 as a TCP port. The ServerIron ADX assumes that ports for which it does not know the type are UDP ports.Refer to “Adding a port and specifying its type” on page 245.

NOTE: To display a list of the ports for which the ServerIron ADX already knows the type, enter the server port ? command at the global CONFIG level.

Keepalive interval and retries

The number of seconds between health checks and the number of times the ServerIron ADX re-attempts a health check to which the server does not respond. Refer to “Changing a port’s keepalive parameters” on page 245.

Keepalive state Whether the ServerIron ADX’s health check for the port is enabled or disabled. Recurring Layer 4 and Layer 7 health checks are disabled by default. When you configure a port profile, the software automatically globally enables the health check for the application. You also can explicitly disable or re-enable the keepalive health check at this level.

NOTE: If you are configuring a port profile for a port that is known to the ServerIron ADX, the keepalive parameters affect Layer 7 health checks. For other ports, the keepalive parameters affect Layer 4 health checks.



Keepalive port By default, the ServerIron ADX bases the health of an application port on the port itself. You can specify a different application port for the health check. In this case, the ServerIron ADX bases the health of an application port on the health of the other port you specify.Refer to “Basing a port’s health on the health of another port” on page 278.

NOTE: You cannot base the health of a port well-known to the ServerIron ADX on the health of another port, whether the port is well-known or not well-known.

Source of health for alias port

By default, the ServerIron ADX performs independent health checks on an alias port and its master port. You can configure the ServerIron ADX to base the health of an alias port on the state of its master port.Refer to “Basing an alias port’s health on the health of its master port” on page 277.

TCP or UDP age The number of minutes a TCP or UDP session table entry can remain inactive before the ServerIron ADX times out the entry. This parameter is set globally for all TCP or UDP ports but you can override the global setting for an individual port by changing that port’s profile. Refer to “Overriding the global TCP or UDP age” on page 248.You can specify a TCP age from 2 through 60 minutes and a multiplier from 2 through 20. Thus, the maximum configurable TCP age for an individual port is 1200 minutes (20 hours).

NOTE: You cannot specify a multiplier when configuring the global TCP age.

NOTE: Because UDP is a connectionless protocol, the ServerIron ADX does not remove a UDP session from its session table until the session times out. TCP is a connection-based protocol. Therefore, for TCP sessions, the ServerIron ADX removes the session as soon as the client or server closes the session.

NOTE: For DNS and RADIUS UDP load balancing, the age value does not follow the normal configuration and default value unless the udp-normal-age option is configured on the port. The default UDP age will always be 2 minutes unless the udp-normal-age option is configured.

NOTE: The ServerIron ADX immediately deletes a UDP DNS or RADIUS session table entry when the ServerIron ADX receives a reply for the application from a real server. If desired, you can configure the ServerIron ADX to age these ports like other UDP ports, using the UDP age timer. Refer to “Enabling normal UDP aging for DNS and RADIUS” on page 160.

Session synchronization

In Symmetric Active-Standby HA configurations, this attribute provides failover for individual sessions on the application port. Normally, existing sessions are not carried over from one ServerIron ADX to another during failover. Refer to “Enabling session synchronization” on page 249.

Connection logging You can enable logging for session table entries created for this port. Refer to “Syslog for session table entries” on page 302.

Slow start Configures the ServerIron ADX to control the rate of new connections to the application port to allow the server to ramp up. Refer to “Port slow-start mechanism” on page 286.

Smooth factor If you plan to use server response time as a load-balancing method, you can adjust the amount of preference the ServerIron ADX gives the most recent response time compared to the previous response time. Refer to “Changing the smooth factor on an application port” on page 249.

Recursive DNS health checks

By default, a Layer 7 health check for a DNS port sends the query only to the real server (DNS server). If the DNS server does not reply with the IP address or zone name requested by the health check, the port fails the health check. You can enable the real server to perform a recursive lookup for the IP address or zone requested by the health check of the well-known DNS port (53). Refer to “Enabling recursive DNS health checks” on page 233.

TABLE 18 Port profile attributes (Continued)

Attribute Description



You also can change port attributes locally, on the real server and virtual server configuration levels. Port profiles simplify configuration by letting you characterize a port globally. For example, if many of your real servers use TCP port 80 (the well-known number for HTTP) and you want to change the keepalive interval for the port, you can do so globally. You do not need to change the value multiple times on each real server.

The ServerIron ADX knows the port types of some well-known port numbers. If you are using a port number for which the ServerIron ADX does not know the port type, you can specify whether the port is TCP or UDP and configure its keepalive values globally. You do not need to define the port on every server.

NOTEUnless a port is known to the ServerIron ADX to be a TCP port, the ServerIron ADX assumes the port is UDP. If you are using a port number that is not known to the ServerIron ADX and the port type is TCP, you must specify this either globally (using a port profile) or locally (when configuring the individual real servers and virtual servers). Otherwise, the ServerIron ADX will use a UDP health check to test the port and the port will fail the health check.

NOTEIf you bind an application port on a real server to the same port on a virtual server, the port on the real server inherits the attributes of the port on the virtual server.



Displaying the session age of a TCP port

To display the session age of a TCP port, enter a command such as the following. The TCP session ages are shown in bold type. Notice that the TCP session ages for ports 8082 and HTTP (80) use multipliers.

Syntax: show server real name detail

Overriding the global TCP or UDP age

The TCP and UDP ages specify how many minutes a TCP or UDP session can remain inactive before the ServerIron ADX closes the session and clears it from its session table. You can set the TCP or UDP age from 2 through 60 minutes. The default TCP age is 30 minutes, and the default UDP age is 5 minutes.

Because UDP is a connectionless protocol, the ServerIron ADX does not remove a UDP session from its session table until the session times out. On the other hand TCP is a connection-based protocol, so for TCP sessions, the ServerIron ADX removes the session as soon as the client or server closes the session.

ServerIronADX(config)#show server real rs1 detailReal Servers Info

Name : rs1 Mac-addr: 0003.47bf.bad2IP:192.168.6.91 Range:1 State:Active Max-conn:1000000Least-con Wt:0 Resp-time Wt:0Src-nat (cfg:op):(off:off) Dest-nat (cfg:op):(off:off)Remote server : No Dynamic : No Server-resets:0Mem:server: 02057999 Mem:mac: 02037cb0

Port State Ms CurConn TotConn Rx-pkts Tx-pkts Rx-octet Tx-octet Reas---- ----- -- ------- ------- ------- ------- -------- -------- ----telnet active 0 0 0 0 0 0 0 0 max_conn = 1000000 sessions = 0 Keepalive(G/L:Off/Off):Off tcp-age: 408083 active 0 0 0 0 0 0 0 0 max_conn = 1000000 sessions = 0 Keepalive(G/L:On/Off):On tcp-age: 408082 active 0 0 0 0 0 0 0 0 max_conn = 1000000 sessions = 0 Keepalive(G/L:On/Off):On tcp-age: 35 * 48081 active 0 1 1 10 19 2280 4380 0 max_conn = 1000000 sessions = 2 Keepalive(G/L:On/Off):On tcp-age: 53http failed 0 0 0 0 0 0 0 0 max_conn = 1 sessions = 0 Keepalive(G/L:On/Off):On Status Code(s): default (200-299, 401) HTTP URL: "HEAD /" tcp-age: 60 * 2default unbnd 0 0 0 0 0 0 0 0 max_conn = 0 sessions = 0

Server Total 1 1 10 19 2280 4380 0



NOTEThe ServerIron ADX immediately deletes a UDP DNS or RADIUS session table entry when the ServerIron ADX receives a reply for the application from a real server. If desired, you can configure the ServerIron ADX to age these ports like other UDP ports, using the UDP age timer. Refer to “Enabling normal UDP aging for DNS and RADIUS” on page 160.

For DNS and RADIUS UDP load balancing, the age value does not follow the normal configuration and default value unless the udp-normal-age option is configured on the port. The default UDP age will always be 2 minutes unless the udp-normal-age option is configured.

To change the global default for all TCP or UDP ports, refer to “Configuring TCP age” on page 301 or “Configuring UDP age” on page 301.

To override the default TCP age and set the age for TCP port 80 to 15 minutes, enter the following commands.

ServerIronADX(config)#server port 80ServerIronADX(config-port-80)#tcp 15


Syntax: tcp | udp age

The default TCP age is 30 minutes. The default UDP age is 5 minutes.

Enabling session synchronization

In Symmetric Active-Standby HA configurations, if the active ServerIron ADX becomes unavailable, service for the VIPs that ServerIron ADX was load balancing is assumed by the backup ServerIron ADX. By default, when a ServerIron ADX with open sessions becomes unavailable, the sessions are not carried over to the standby ServerIron ADX. Instead, the sessions end and must be re-established by the clients or servers.

You can configure session failover on an individual TCP or UDP port basis by enabling session synchronization in the port’s profile.

To enable session synchronization for port 80, enter the following commands.

ServerIronADX(config)#server port 80ServerIronADX(config-port-80)#session-sync


Syntax: [no] session-sync

NOTEIn case of port translation, enable session synchronization for both the VIP virtual port and the real server port.

Changing the smooth factor on an application port

This smooth factor applies to ports that you plan to use with the server response time load-balancing metric. Refer to “Changing the Load-Balancing Predictor Method” on page 42 and “Configuring a stateless port” on page 51 for information about the server response time metric and how the smooth time works.


Port policy4

The ServerIron ADX calculates the server response time value for a real server by regularly collecting response time samples, then using a calculation to smooth the values of the samples and derive a single response time value for the real server. The ServerIron ADX collects the samples around once every 100 milliseconds (about 10 times a second). The sampling rate can vary slightly depending on the processing the ServerIron ADX is performing.

To change the smooth factor for an application port, enter a command such as the following.

ServerIronADX(config-port-80)#smooth-factor 50

Syntax: smooth-factor num

Port policy

Port policies Server port policies help reduce the configuration required for health checks and provide more flexibility while configuring health checks.

Previously, ServerIron ADX allowed the use of Layer 7 health check parameters for known ports, such as HTTP, LDAP, SMTP, IMP4, POP3, NNTP, Telnet, and FTP, to check the health of unknown ports. For example, a configuration such as the following can be entered.

ServerIronADX(config)#server port 999ServerIronADX(config-port-999)#tcp keepalive protocol smtp

In this release, health checks for SSL, RTSP, MMS, PNM, and LDAPS have been added to check the health of unknown ports, using the server port-policy command.

The configuration of server port policies consists of two parts:

• Configuring a port policy

• Binding the policy

Configuring a port policyFollow the steps given below to configure a port policy.

1. First create a policy by entering a command such as the following.

ServerIronADX(config)#server port-policy p1

Syntax: server port-policy policy-name

Once the policy is named, the CLI changes to the configuration-port-policy level.

2. (Optional) Specify the port that will be checked by the policy.

ServerIronADX(config-port-policy-name)#port 8080

Syntax: port port-num


Port policy 4

3. Specify what protocol will be checked on the traffic that passes through the port.

ServerIronADX(config-port-policy-name)#protocol http

Syntax: protocol protocol-value

If the protocol is not configured, the policy cannot be bound to a real server port.

Enter a TCP or UDP port name or number for protocol-value. For TCP ports, enter FTP (port 21), HTTP (port 80), IMAP4 (port 143), LDAP (port 389), LDAPS (port 636), MMS (port 1755), NNTP (port 119), PNM (port 7070), POP3 (port 110), RTSP (port 554), SMTP (port 25), TELNET (port 23).

NOTEPorts 20 and 21 both are FTP ports but on the ServerIron, the name "FTP" corresponds to port 21.

For UDP ports, enter DNS (port 53) or RADIUS (port 1812).

4. Configure a keepalive interval under a port policy.

ServerIronADX(config-port-policy-pp1)#keepalive-interval 5

Syntax: [no] keepalive-interval seconds

Refer to “Configuring a keepalive interval under a port policy” on page 254 for more details.

5. (Optional) Enter the number of times the policy will be tried before the ServerIron ADX marks the port as "UP" or "DOWN".

ServerIronADX(config-port-policy-name)#retries 5

Syntax: retries num

The default is 3 tries.

6. (Optional) Specify the protocol value.

ServerIronADX(config-port-policy-name)#protocol http url www.example3.com

Syntax: protocol protocol-options

Enter one of the following for protocol-options, specifying the values for the required parameters:

• http status-code min max

• http url url

• http content-match match-list

• dns addr-query value

• dns zone value

• {ldap | ldaps} username name

• {ldap | ldaps} password password

• {ldap | ldaps} search-base-dn distinguished-name

• radius key radius-key

• radius password value

• radius nas-ip { ipv4-addr | ipv6-addr }

• radius nas-port value


Port policy4

7. (Optional) Enable the Layer 4 check feature in the policy.

ServerIronADX(config-port-policy-name)#l4-check

Syntax: l4-check

By default, Layer 7 health check is enabled; however, Layer 4 health check is not. You must enable Layer 4 health check if you want to use that feature.

Binding the policyAfter the policy is configured, return to the configuration level and bind the policy to a real server port.

ServerIronADX(config)#server real r1 10.10.1.101ServerIronADX(config-rs-name)#port 1234 use-port-policy p1

Syntax: server real real-server-name real-server-ip-address

Syntax: [no] port port-num use-port-policy policy-name

For the policy-name variable, enter the name of the policy you created.

Once a policy is bound to a real server port, the ServerIron ADX will use the values configured in the policy for health checks.

The ServerIron ADX sends a health check to the port configured in the policy; however, if you do not configure a port number in the policy, the ServerIron ADX sends the health check to the port to which it is bound.

NOTEThe port policy configuration will take precedence over a port profile.

Example 1:

ServerIronADX(config)#server port-policy p1ServerIronADX(config-port-policy-p1)#port 8080ServerIronADX(config-port-policy-name)#protocol sslServerIronADX(config-port-policy-name)#retries 5ServerIronADX(config-port-policy-name)#exitServerIronADX(config)#server real r1 10.10.1.101ServerIronADX(config-rs-r1)#port 1234 use-port-policy p1ServerIronADX(config-rs-r1)#port 1234 keepalive

In Example 1, Port 1234 on Real Server 1 will be marked as “UP”, if the Layer 7 health check on Port 8080 on the server with the IP address of 10.10.1.101 passes.

Example 2:

ServerIronADX(config)#server port-policy p2ServerIronADX(config-port-policy-name)#protocol httpServerIronADX(config-port-policy-name)#l4-checkServerIronADX(config-port-policy-name)#exitServerIronADX(config)#server real r2 10.10.1.102ServerIronADX(config-rs-r1)#port 1234 use-port-policy p2


Port policy 4

In Example 2, a port has not been configured for "policy p2," so the ServerIron ADX will use the port to which the policy is bound. Port 1234 of real server r2 will be marked as "UP" if the health check to port 1234 on the 10.10.1.101 Server passes the Layer 4 health-check.

Example 3:

In the following example, Port Policy pp1 is configured with a keepalive interval of 5 seconds, while Port Policy pp2 has a keepalive interval of 30 seconds.

Port Policy pp1 is bound to real server rs1 port 8080 and real server rs2 port 9090; therefore, these two ports have a 5 second keepalive interval.

Port Policy pp2 is bound to real server rs3 port 8080 and real server rs4 port 9090. These two ports have a keepalive interval of 30 seconds.

ServerIronADX(config)#server port-policy pp1ServerIronADX(config-port-policy-pp1)#keepalive-interval 5ServerIronADX(config-port-policy-pp1)#protocol httpServerIronADX(config-port-policy-pp1)#protocol http url "GET /abc.html"ServerIronADX(config-port-policy-pp1)#retries 3ServerIronADX(config-port-policy-pp1)#exitServerIronADX(config)#server port-policy pp2ServerIronADX(config-port-policy-pp2)#keepalive-interval 30ServerIronADX(config-port-policy-pp2)#protocol httpServerIronADX(config-port-policy-pp2)#protocol http url "GET /xyz.html"ServerIronADX(config-port-policy-pp2)#retries 2ServerIronADX(config-port-policy-pp2)#exitServerIronADX(config)#server real rs1ServerIronADX(config-rs-r1)#port 8080ServerIronADX(config-rs-r1)#port 8080 use-port-policy pp1ServerIronADX(config-rs-r1)#exit ServerIronADX(config)#server real rs2ServerIronADX(config-rs-r2)#port 9090ServerIronADX(config-rs-r2)#port 9090 use-port-policy pp1ServerIronADX(config-rs-r2)#exitServerIronADX(config)#server#real rs3ServerIronADX(config-rs-r3)#port 8080ServerIronADX(config-rs-r3)#port 8080 use-port-policy pp2ServerIronADX(config-rs-r3)#exitServerIronADX(config)#server real rs4ServerIronADX(config-rs-r4)#port 9090ServerIronADX(config-rs-r4)#port 9090 use-port-policy pp2ServerIronADX(config-rs-r4)#exit


Port policy4

Configuring a keepalive interval under a port policyYou can specify a health check keepalive interval from under a port-policy definition.

ServerIronADX(config-port-policy-pp1)#keepalive-interval 5

Syntax: [no] keepalive-interval seconds

Enter from 1 through 120 for the seconds variable.

In the following example, real server rs1 port 8080 and real server rs2 port 9090 will have a keepalive interval of 5 seconds. Also, real server rs1 port 8080 and real server rs4 port 9080 will have a keepalive interval of 30 seconds.

ServerIronADX(config)#server port-policy pp1ServerIronADX(config-port-policy-pp1)#keepalive-interval 10ServerIronADX(config-port-policy-pp1)#protocol httpServerIronADX(config-port-policy-pp1)#protocol http url "GET /abc.html"ServerIronADX(config-port-policy-pp1)#retries 3ServerIronADX(config-port-policy-pp1)#exit

ServerIronADX(config)#server port-policy pp2ServerIronADX(config-port-policy-pp2)#keepalive-interval 30ServerIronADX(config-port-policy-pp2)#protocol httpServerIronADX(config-port-policy-pp2)#protocol http url "GET /xyz.html"ServerIronADX(config-port-policy-pp2)#retries 2ServerIronADX(config-port-policy-pp2)#exit

After configuring the policy, bind it to a real server port. (Refer to “Binding the policy” on page 252 for details.) For example:

ServerIronADX(config)#server real rs1ServerIronADX(config-rs-rs1)#port 8080ServerIronADX(config-rs-rs1)#port 8080 keepaliveServerIronADX(config-rs-rs1)#port 8080 use-port-policy pp1ServerIronADX(config-rs-rs1)#exit



ServerIronADX(config)#server real rs4ServerIronADX(config-rs-rs4)#port 9090ServerIronADX(config-rs-rs4)#port 9090 keepaliveServerIronADX(config-rs-rs4)#port 9090 use-port-policy pp2


Element health checks 4

Health check policy for VIP port

Overview of health check policy for VIP port

NOTEThe ServerIron ADX does not currently support interval configuration under server port policy.

The ServerIron ADX currently has support binding a server port policy on a real server port. Because multiple real server ports are bound to a single virtual port, the client has requested that the server port policy be bound to a virtual port. Once bound to a virtual port, the policy takes effect on all the real server ports that are bound to that virtual port. This method allows the running configuration to be reduced.

Command line interface

The command to turn on the health check policy feature for VIP port is under virtual server configuration.

ServerIronADX(config)#server virtual-name-or-ip v1 10.1.1.1ServerIronADX(config-virtual-server-v1) port 80ServerIronADX(config-virtual-server-v1) bind 80 r1 80 r2 80 r3 80ServerIronADX(config-virtual-server-v1) port 80 use-port-policy policy1

The ServerIron ADX will now use the values configured under server port policy "policy1" to send out health-checks to ports 80 on R1, R2 and R3.

Element health checks

IntroductionThe ServerIron ADX allows the creation of a health check that is customized for a given application server. Such definition is also known as element health check. You can specify the health check frequency, the number of retrials, and the number of other parameters for server health check.

Configuring element-action expressionsAn element-action expression contains the IP address, protocol (TCP or UDP), and application port number for an application on an individual real server. If the ServerIron ADX allows you to customize Layer 7 information for the application, then the element-action expression also can contain the customized Layer 7 information.

You also can change the following parameters for an application port when configuring an element-action expression:

• Health check type – For application types that are well-known to the ServerIron ADX, you can specify whether you want to use the Layer 4 health check or the Layer 7 health check for the port. By default, the ServerIron ADX uses the Layer 7 health check if the port is one of the types that are well known to the ServerIron ADX.

• Health check interval – By default, the ServerIron ADX performs the health checks every 5 seconds. You can change the interval to a value from 2 through 120 seconds.


Element health checks4

• Health retries – By default, if a reply to a health check is not received, the ServerIron ADX will attempt the health check two more times before concluding that the application has failed the health check. You can change the number of retries to a value from 1 through 5 retries.

• Health check state – By default, the health check is enabled as soon as you configure it. You can disable or re-enable the health check from within the element-action expression for the check.

Specifying the IP address and application port parameters

To configure an element-action expression, enter commands such as the following. The commands in these examples specify the IPv4 or IPv6 address of the real server and the application port on the server.

Example for IPv4

ServerIronADX(config)#healthck check1 tcpServerIronADX(config-hc-check1)#dest-ip 10.10.10.50ServerIronADX(config-hc-check1)#port http

Example for IPv6

ServerIronADX(config)#healthck check-v6 tcpServerIronADX(config-hc-check-v6)#dest-ip 2001:db8:2000::1ServerIronADX(config-hc-check-v6)#port http

These commands change the CLI to the configuration level for an element-action expression, then specify the IPv4 or IPv6 address of the real server and the application port on the server. Because the specified application is well-known to the ServerIron ADX, the ServerIron ADX automatically associates the default health check parameters for the port with the element-action expression. In this example, the port is HTTP (80), so the ServerIron ADX associates the default HTTP health check parameters with the element-action expression. By default, the ServerIron ADX sends a HEAD request for the default page,

NOTEYou must specify the destination IP address before you can specify other health check parameters. The software creates the health check policy only after you specify the destination IP address. If you try to specify another parameter before the destination IP address, the CLI displays an error message such as the following: Error - check1: Health-check element is undefined.

NOTEIf you do not specify the application port, the ServerIron ADX will list the status of the health check as FALSE (failed).



To configure an element-action expression for a port number that is not well-known to the ServerIron ADX, enter commands such as the following.

Example for IPv4

ServerIronADX(config)#healthck check1 tcpServerIronADX(config-hc-check1)#dest-ip 10.10.10.50ServerIronADX(config-hc-check1)#port 8080ServerIronADX(config-hc-check1)#protocol http

Example for IPv6

ServerIronADX(config)#healthck check-v6 tcpServerIronADX(config-hc-check-v6)#dest-ip 2001:db8:2000::1ServerIronADX(config-hc-check-v6)#port 8080ServerIronADX(config-hc-check-v6)#protocol http

These commands configure an element-action expression for unknown port 8080 and associate the default health check parameters for port 80 with the unknown port. To customize the Layer 7 health check parameters for a port, add the information with the protocol command, as in the following example.

Example for IPv4

ServerIronADX(config)#healthck check1 tcpServerIronADX(config-hc-check1)#dest-ip 10.10.10.50ServerIronADX(config-hc-check1)#port 8080ServerIronADX(config-hc-check1)#protocol http url "GET /sales.html"

Example for IPv6

ServerIronADX(config)#healthck check-v6 tcpServerIronADX(config-hc-check-v6)#dest-ip 2001:db8:2000::1ServerIronADX(config-hc-check-v6)#port 8080ServerIronADX(config-hc-check-v6)#protocol http url "GET /sales.html"

The protocol command in this example changes the Layer 7 health check parameters for this HTTP port to a GET request for a page named "sales.html".

Syntax: [no] healthck string { tcp | udp | boolean | icmp }

This command begins configuration of the element-action expression. The string variable specifies the name for the expression and can be up to 20 characters long. The tcp or udp parameter specifies whether you are configuring an expression for a TCP application port or a UDP application port. There is no default.

Syntax: [no] dest-ip { ipv4-addr | ipv6-addr }

The ipv4-addr variable specifies the IPv4 address of the real server.



This command specifies the application port number.

NOTEIf you do not specify the server IP address and the application port, the ServerIron ADX will list the status of the health check as FALSE (failed).



You can specify any valid number, or one of the following port names well-known to the ServerIron ADX:

• dns – port 53

• ftp – port 21. (Ports 20 and 21 both are FTP ports but in the ServerIron ADX, the name “ftp” corresponds to port 21.)

• http – port 80

• imap4 – port 143

• ldap – port 389

• nntp – port 119

• ntp – port 123

• pop2 – port 109

• pop3 – port 110

• radius – port 1812

• radius-old –The ServerIron ADX name for UDP port 1645, which is used in some older RADIUS implementations instead of port 1812.

• smtp – port 25

• snmp – port 161

• ssl – port 443

• telnet – port 23

• tftp – port 69

NOTEIf you enter the no port tcp/udp-port command to remove the port, the ServerIron ADX also removes the protocol tcp/udp-port command (see below) if the port is well-known to the ServerIron ADX. The reason is that the ServerIron ADX automatically uses the protocol that matches the well-known port. For ports that are not well-known types, the ServerIron ADX does not remove the protocol. You must remove it separately.

Syntax: [no] protocol tcp/udp-port

This command specifies a port whose health-check mechanism you want to use for the port specified by the port command. You need to use this command only if the port specified by the port command is not one of the ports listed above but the port is the same type as one of the ports listed above. For example, use this command if you want to use the DNS health-check mechanism for a port other than 53.

NOTEYou must specify the port using the port command before you enter the protocol command. If the port command specified a port that is well-known to the ServerIron ADX, the ServerIron ADX automatically uses the protocol that matches the port; you do not need to specify it and cannot change it.



NOTEIf you remove the Layer 7 health check information (using a no protocol command), the application will fail the health check. If you want the ServerIron ADX to use a Layer 4 health check instead, enter the l4-check command to change the health-check type to Layer 4.

If the port is not well-known to the ServerIron ADX and you do not specify a protocol for the Layer 7 health check, but Layer 7 health checking is enabled for the port, the port will fail the health check.

Refer to the “Changing the health-check type” on page 262.

For some ports, you also can customize the Layer 7 information sent with the health check. Here is the syntax.

Syntax: [no] protocol http | 80 [url “[GET | HEAD] [/]URL-page-name” | port http status_code range [range[range[range]]] | content-match matching-list-name]

This command changes one of the following HTTP health-check parameters. To change more than one of these parameters, enter a separate protocol http or protocol 80 command for each parameter.

• url “[GET | HEAD] [/]URL-page-name” – This parameter specifies whether the HTTP health check performs a GET request or a HEAD request. For GET requests, you can specify the page that is requested. By default, a GET request asks for page “1.0”.

• port http status_code range [range[range[range]]] – This parameter changes the HTTP status codes that the ServerIron ADX will accept as valid responses. Each range variable specifies the low number and high number in a range of status codes. You can specify up to four ranges (total of eight values). To specify a single message code for a range, enter the code twice. For example, to specify 200 only, enter the port http status_code 200 200 command. For SLB, the default status code range is from 200 through 299. If the server’s reply to the health check contains a status code within this range, the ServerIron ADX considers the HTTP application to be healthy.

• content-match matching-list-name – This parameter attaches a match list for an HTTP content verification health check to the real server. An HTTP content verification health check is a type of Layer 7 health check in which the ServerIron ADX examines text in an HTML file sent by a real server in response to an HTTP keepalive request. The ServerIron ADX searches the text in the HTML file for user-specified selection criteria and determines whether the HTTP port on the real server is alive based on what it finds. The selection criteria used in HTTP content verification is contained in a matching list that is attached to one or more real servers. The following is an example of the commands used to set up a matching list. For information on how to configure the match lists, refer to “Configuring HTTP content matching lists” on page 266.

Syntax: [no] protocol dns | 53 [addr_query "name" | zone zone-name]



This command changes one of the following DNS health-check parameters. To change more than one of these parameters, enter a separate protocol dns or protocol 53 command for each parameter.

• addr_query "name" – This parameter specifies a domain name to be requested from the real server by the ServerIron ADX. If the server successfully responds with the IP address for the domain name, the server passes the health check. There is no default.

• zone zone-name – This parameter specifies a DNS zone name. The ServerIron ADX sends a Source-of-Authority (SOA) request for the zone name. If the server is authoritative for the zone and successfully responds to the SOA request, the server passes the health check. There is no default.

NOTEIf you do not configure one of these parameters, the DNS port will fail the health check.

Syntax: [no] protocol radius | 1812 [username string] | [password string] | [key string]

This command changes one of the following RADIUS health-check parameters. The health check requests values that are configured on the RADIUS server. To change more than one of these parameters, enter a separate protocol radius or protocol 1812 command for each parameter.

• username string – This parameter specifies an authentication username on the server.

• password string – This parameter specifies an authentication password on the server.

• key string – This parameter specifies an authentication key on the server.

Syntax: [no] protocol ldap | 389 [num]

This command changes the LDAP version. The health check sent by the ServerIron ADX differs depending on the version. You can specify 2 or 3. The default is 3.

Using SSL health checks in a health check policy

When SSL health checks are used in a health check policy, by default the simple SSL health check is used. The ServerIron ADX sends the server an SSL client hello with the SSL SID set to 0; if the server responds, it passes the health check. However, if you use the protocol ssl use-complete command in a health check policy, it causes the ServerIron ADX to negotiate an SSL connection and send a GET or HEAD request to the server.

For example, the following commands create a health check policy to test IP address 10.10.10.50, using SSL health checks.

ServerIronADX(config)#healthck check4 tcpServerIronADX(config-hc-check4)#dest-ip 10.10.10.50ServerIronADX(config-hc-check4)#port sslServerIronADX(config-hc-check4)#protocol ssl use-completeServerIronADX(config-hc-check4)#protocol ssl url "GET /secure.htm"ServerIronADX(config-hc-check4)#protocol ssl status-code 200 200ServerIronADX(config-hc-check4)#protocol ssl content-match m1ServerIronADX(config-hc-check4)#l7-check ServerIronADX(config-hc-check4)#enable ServerIronADX(config-hc-check4)#exit

Syntax: [no] protocol ssl use-complete



Changing the health-check interval and retries

By default, the ServerIron ADX performs a health check every 5 seconds. If a reply is not received, the ServerIron ADX will attempt the health check two more times before concluding that the application has failed the health check. You can change the number of seconds the ServerIron ADX will wait for a reply to a health check and the number of retries.

NOTEThe number of retries is the total number of attempts the ServerIron ADX will make. If you use the default interval and retries values, the ServerIron ADX will send up to three health-check packets, at 5-second intervals. If a server does not respond within 15 seconds of the time the ServerIron ADX sent the first health-check packet, the server fails the health check and the ServerIron ADX concludes that the server is not available.

To change the interval for a health check, enter a command such as the following at the configuration level for the element-action expression that contains the health check.

ServerIronADX(config-hc-check1)#interval 30

Syntax: [no] interval secs

You can specify from 2 through 120 seconds. The default is 5 seconds.

To change the number of retries for a health check, enter a command such as the following at the configuration level for the element-action expression that contains the health check.

ServerIronADX(config-hc-check1)#retries 4

Syntax: [no] retries num

You can specify from 1 through 5 retries. The default is 3 retries.

NOTEYou also can globally change the interval and retries for an application port by editing its port profile. Refer to “Configuring a port profile” on page 244.



Changing the health-check type

For TCP application ports, you can change the health-check type between Layer 4 and Layer 7. By default, the ServerIron ADX performs a Layer 7 health check in the following cases:

• The port is one of the following ports well-known to the ServerIron ADX:

- FTP – port 21. (Ports 20 and 21 both are FTP ports but on the ServerIron ADX, the name “FTP” corresponds to port 21.)

- HTTP – port 80

- IMAP4 – port 143

- LDAP – port 389

- MMS – port 1755

- NNTP – port 119

- PNM – port 7070

- POP3 – port 110

- RTSP – port 554

- SMTP – port 25

- SSL – port 443

- TELNET – port 23

• The port is not well-known to the ServerIron ADX but you used the protocol command to specify the protocol of one of the well-known ports. By specifying the protocol, you configure the ServerIron ADX to use the protocol’s Layer 7 health-check method for the port.

If the TCP port is not one of the ports above or you did not specify a Layer 7 health-check method (using the protocol command), the ServerIron ADX uses the Layer 4 health check for TCP.

NOTEChanging the health-check type for UDP application ports has no effect. If the application port is RADIUS (1812) or DNS (53) or uses the health-check method of one of these ports, the ServerIron ADX uses a Layer 7 health check. Otherwise, the ServerIron ADX uses the Layer 4 health check for UDP.



The Layer 7 health-check methods differ depending on the application:

• TCP – The ServerIron ADX attempts to engage in a normal three-way TCP handshake with the port on the real server:

- The ServerIron ADX sends a TCP SYN packet to the port on the real server.

- The ServerIron ADX expects the real server to respond with a SYN ACK.

- If the ServerIron ADX receives the SYN ACK, the ServerIron ADX sends a TCP RESET, satisfied that the TCP port is alive.

• UDP – The ServerIron ADX sends a UDP packet with garbage (meaningless) data to the UDP port:

- If the server responds with an ICMP “Port Unreachable” message, the ServerIron ADX concludes that the port is not alive.

- If the server does not respond at all, the ServerIron ADX assumes that the port is alive and received the garbage data. Because UDP is a connectionless protocol, the ServerIron ADX and other clients do not expect replies to data sent to a UDP port. Therefore, lack of a response is a good outcome.

ServerIronADX(config-hc-check1)#l4-check

The command in this example configures the ServerIron ADX to use the Layer 4 health check for the application port in the element-action expression. Because the application port in this element-action expression is HTTP, the ServerIron ADX will use the Layer 4 health check for TCP.

Syntax: [no] l4-check | l7-check

Changing the health-check state

Once you configure an element-action expression, the health check in the expression is enabled by default. To disable the health check, enter the following command at the configuration level for the element-action expression.

ServerIronADX(config-hc-check1)#disable

Syntax: [no] disable | enable

NOTEHealth checking (keepalive) also must be enabled on the port profile level or the real server level. Otherwise, the health-check policy is used during initial bringup of the server but is not used for periodic health checks after the server is brought up.

NOTEIf the health check for an application on a server is disabled, the ServerIron ADX assumes that the server and application are healthy and continues to send client requests to the server.

NOTEIf you change the health-check state from within the element-action expression, this state overrides the health-check state configured in the port profile for the application port or in the real server configuration.

NOTEYou can globally enable or disable all health-check policies. Refer to “Globally disabling all health-check policies” on page 281.



Attaching a health-check policy to an application port on a serverAfter you configure logical expressions, you can attach them to application ports on real servers. The ServerIron ADX does not begin sending health-check packets until you attach the policy to a real server port.

To attach a health-check policy to an application port on a server, enter commands such as the following.

ServerIronADX(config)#server real-name R1 10.10.10.50ServerIronADX(config-rs-R1)#port 80 healthck “check1”

This command configures the ServerIron ADX to base the health of application port 80 on real server R1 on the results of the check1 health-check policy.

Displaying health-check policies and their statusTo display a list of the configured health-check policies and their current status, enter the following command.

Syntax: show healthck

Table 19 displays the health-check policy status.

TABLE 19 Health-check policy status

Field Description

Total nodes The number of health-check policies in the configuration. The number includes attached and unattached policies.

Max nodes The maximum number of health-check policies you can configure.

Name The element-action expression or policy name.

Value The current value of the policy. The value can be one of the following:• TRUE – The most recent health check performed using this policy was successful. The

ServerIron ADX received a valid reply to the health check.• FALSE – The most recent health check performed using this policy was unsuccessful.• N/B – The health check is not bound to any VIP and thus is not in use.• N/A (Not Attached) – The policy is not attached to a real server.

NOTE: If the policy is disabled, this value is always TRUE, because the ServerIron ADX assumes a server is healthy unless its health check is enabled and the server has not responded appropriately to the health check.

ServerIronADX(config-hc-check1)#show healthckTotal nodes: 6; Max nodes: 128 Name Value Enable Type Dest-IP Port Proto Layer-------------------------------------------------------------------------------- check1 TRUE YES tcp 10.10.10.50 http http l4-chk check2 TRUE YES tcp 10.10.10.40 http http l7-chk check3 TRUE NO udp 10.10.10.30 http http l4-chk check4 TRUE NO udp 10.10.10.40 http http l4-chk check5 N/A NO udp - dns dns l4-chk httpsrvr TRUE YES and check1 check2 nested1 N/A na and check1 check2 nested2 N/A na or check3 check4



Displaying health-check policy statisticsTo display health-check policy statistics, enter the following command.

ServerIronADX(config)#show healthck statisticsPing Statistics:Sent: 1524 Received: 1524Invalid Replies: 0 Dropped Replies: 0

Syntax: show healthck statistics

Table 20 displays the health-check policy statistics.

Enable The state of the policy, which can be one of the following:• YES – The policy is enabled.• NO – The policy is disabled.• na (not applicable) – This field does not apply to the policy. This value indicates that the

policy is not attached to a real server.

Type The element-action expression or policy type. For Layer 3 health checks, this information consists of ICMP and the IP address tested by the health check. Values can be one of the following:• tcp – An element-action expression for a TCP application port.• udp – An element-action expression for a UDP application port.• and – A policy containing element-action expressions joined by AND.• or – A policy containing element-action expressions joined by OR.

Dest-IP For element-action expressions, the IP address of the real server. For policies, this field shows the element-action expressions in the policy.The value “ - ”indicates that the IP address has not been specified.

Port For element-action expressions, the application port. This field does not apply to policies.

Proto For element-action expressions, the health-check method to be used for the port.

NOTE: If the value is " - ", the protocol has not been specified and the port is not well-known to the ServerIron ADX.

Layer The type of health check, which can be one of the following:• l4-chk – Layer 4 TCP or UDP health check.• l7-chk – Layer 7 application-specific health check.

TABLE 20 Health-check policy statistics

Field Description

Sent The number of health-check packets sent by bound health-check policies.

Received The number of replies received. A received reply results in a true condition.

NOTE: Since the ServerIron ADX retries a health check if a reply is not received, a higher sent count than receive count does not necessarily indicate a problem.

Invalid Replies The number of replies that were received that had an invalid ID. The ServerIron ADX is sometimes able to resolve an invalid ID. If the ServerIron ADX cannot resolve the invalid ID, the device drops the reply and increments the Dropped Replies counter.

Dropped Replies The number of replies that the ServerIron ADX dropped.

TABLE 19 Health-check policy status (Continued)

Field Description


Health check with content match4

Clearing health-check policy statisticsTo clear health-check policy statistics, enter the following command.

ServerIronADX(config)#clear healthck statistics

Syntax: clear healthck statistics

Health check with content match

Content match for HTTP

Configuring HTTP content matching lists

The ServerIron ADX currently supports compound and simple content-matching statements under the match-list configuration. This enhancement adds support for "start" and "end" statements in the match-list configuration.

ServerIronADX(config)#http match-list m1ServerIronADX(config-real-server-r1)#down start "404"ServerIronADX(config-real-server-r1)#default upServerIronADX(config)#http match-list m2ServerIronADX(config-real-server-r1)#up end "found"ServerIronADX(config-real-server-r1)#default down

The first match list m1 would cause the ServerIron ADX to mark the port failed if the text "404" is found at the beginning of the reply from the server. If the text is not found, the ServerIron ADX would mark the port UP, as the default configured is UP.

In the second example above, for match-list m2, ServerIron ADX would mark the port UP, if the text "found' is present at the end of the reply from the server.

An HTTP content verification health check is a type of Layer 7 health check in which the ServerIron ADX examines text in an HTML file sent by a real server in response to an HTTP keepalive request. The ServerIron ADX searches the text in the HTML file for user-specified selection criteria and determines whether the HTTP port on the real server is alive based on what it finds.

The selection criteria used in HTTP content verification is contained in a matching list that is bound to one or more real servers.

To configure a matching list, enter commands such as the following.

ServerIronADX(config)#http match-list m1ServerIronADX(config-http-ml-m1)#down simple "404"ServerIronADX(config-http-ml-m1)#down simple "File Not Found"ServerIronADX(config-http-ml-m1)#exit


Health check with content match 4

The first command sets the name of the matching list and enters the HTTP matching list CLI level. The first down statement looks for the text “404” in the HTML file sent from the real server in response to an HTTP keepalive request; the second down statement looks for the text “File Not Found.” If either of these text strings are found in the HTML file, the ServerIron ADX marks port 80 (HTTP) on the real server FAILED. If neither of the text strings are found, the ServerIron ADX marks the port ACTIVE.

Syntax: http match-list matching-list-name

Syntax: down I up simple text [log]

The down simple and up simple statements specify the selection criteria in the matching list.

NOTEThere is a limit of 200 selection criteria statements for all HTTP matching lists; that is, the total number of up and down statements in all HTTP matching lists on the ServerIron ADX must not exceed 200.

NOTEThe HTTP page file size returned by the server should be less than 100kb.

When an HTML file meets more than one set of selection criteria in a matching list, the ServerIron ADX takes one of the following actions:

• If the strings that meet the selection criteria are different, the ServerIron ADX takes action based on the string that comes first in the file. For example:

ServerIronADX(config)#http match-list m2ServerIronADX(config-http-ml-m2)#down simple "monkey"ServerIronADX(config-http-ml-m2)#up simple "elephant"ServerIronADX(config-http-ml-m2)#exit

The selection criteria in the matching list above would cause the ServerIron ADX to mark the port FAILED if the text "monkey" is found and ACTIVE if the text "elephant" is found. If the HTML file has the text "monkey" at the beginning and "elephant" at the end, the ServerIron ADX would mark port 80 on the real server FAILED, because "monkey" occurs first in the file.

• If a string that meets the selection criteria is a subset of another, the longer string takes precedence, regardless of where it occurs in the file. For example:

ServerIronADX(config)#http match-list m3ServerIronADX(config-http-ml-m3)#down simple "elephant"ServerIronADX(config-http-ml-m3)#up simple "elephantine"ServerIronADX(config-http-ml-m3)#exit

In this example, ServerIron ADX would mark the port FAILED if the text “elephant” is found and ACTIVE if the text “elephantine” is found. If the HTML file has the text “elephant” at the beginning and “elephantine” at the end, the ServerIron ADX would mark port 80 on the real server ACTIVE, because “elephantine” is longer than “elephant”.

The following is an example of a matching list that uses compound selection criteria, in which the beginning and ending parts of selection criteria are specified.

ServerIronADX(config)#http match-list m4ServerIronADX(config-http-ml-m4)#up compound "monkey see" "monkey do" logServerIronADX(config-http-ml-m4)#down compound "500" "Internal Server Error" logServerIronADX(config-http-ml-m4)#down compound "503" "Service Unavailable" logServerIronADX(config-http-ml-m4)#default downServerIronADX(config-http-ml-m4)#exit



In this example, the default down command causes port 80 on the real server to be marked FAILED if none of the selection criteria are found in the HTTP response message.

Syntax: down | up compound start end [log]

Syntax: default down | up

In this matching list, the up and down commands include the compound parameter, which allows you to specify beginning and ending parts of a set of selection criteria. Text that begins with the first part and ends with the second part meets the selection criteria.

In this example, the up command specifies that if the HTML file sent from the real server in response to an HTTP keepalive request contains a text string that begins with the text “monkey see” and ends with the text “monkey do”, port 80 on the real server is marked ACTIVE. The down commands specify that if the HTML file contains a text string that begins with “500” and ends with “Internal Server Error” or begins with “503” and ends with “Service Unavailable”, the port is marked FAILED.

The default command specifies what happens if none of the HTML text in the HTTP response message meets the selection criteria. You can specify either up or down; the default is up. If the real server responds to the health check with a RST, the port is marked ACTIVE or FAILED depending on what was specified in the default statement in the matching list.

The log parameter causes the following warning message to be logged when the selection criteria is met.

00d00h00m00s:W:HTTP match-list matching-list with compound pattern1 start and pattern2 end Alert: bring server down and Extract message: text-between-start-and-end-pattern

In the example, at the successful completion of an HTTP content verification health check, the following message would be logged; that is, if the HTML file sent from the real server in response to an HTTP keepalive request contains a text string that begins with the text “monkey see” and ends with the text “monkey do”.

ServerIronADX#show loggingSyslog logging: enabled (0 messages dropped, 0 flushes, 0 overruns) Buffer logging: level ACDMEINW, 1 messages logged level code: A=alert C=critical D=debugging M=emergency E=error I=informational N=notification W=warning

Dynamic Log Buffer (50 entries):02d04h47m12s:W:HTTP match-list m4 with compound pattern1 "monkey see" and pattern2 "monkey do" Alert: bring server up and Extract message: This web page is configured correctly



Displaying HTTP match lists

To display the contents of matching lists configured on the ServerIron ADX, enter the following command.

Syntax: show http match-list

Binding the matching list to the real servers

To enable HTTP content verification on the ServerIron ADX, you bind the matching list to one or more real servers, by entering commands such as the following.

ServerIronADX(config)#server real-name rs1 192.168.1.1ServerIronADX(config-rs-rs1)#port http content-match m4ServerIronADX(config-rs-rs1)#port http url "GET/monkey.html"ServerIronADX(config-rs-rs1)#exit

Syntax: server real-name real-server-name ip-addr

Syntax: port http content-match matching-list-name

Syntax: port http url “[GET | HEAD] [/]URL-page-name”

In this example, the port http content-match m4 command binds matching list m4 to real server rs1. HTTP response messages coming from real server rs1 are examined using the selection criteria in matching list m4.

The port http url command sets the method used for HTTP keepalive requests and the URL of the page to be retrieved. This command is used in HTTP content verification health checks because the default method and URL page for HTTP keepalive requests used in HTTP health checks, “HEAD /1.0”, does not return an HTML file that the ServerIron ADX can search and verify. You can instead specify the GET method, which does return an HTML file that can be examined using the matching list.

ServerIronADX#show http match-listhttp match-list m1 down simple "404" down simple "File Not Found"http match-list m4 default down up compound "monkey see" "monkey do" log down compound "500" "Internal Server Error" log down compound "503" "Service Unavailable" log



Content match for non-HTTP ports

Configuring scripted health checks

You can configure scripted health checks (also known as content checking), which are content verification health checks for ports that do not use one of the well-known port numbers recognized by the ServerIron ADX. Previous releases supported content verification health checks on port 80 only.

In a scripted health check, the ServerIron ADX opens a connection to a port on a real server by sending a SYN packet. The ServerIron ADX completes the three-way handshake and then waits for the server to send a packet containing ASCII strings in response. It then searches for the configured ASCII string in the received packet. The port on the real server is then marked ACTIVE or FAILED, based on configuration settings in the matching list. For example, a matching list can be configured to mark a port ACTIVE or FAILED if the string is found, or mark the port ACTIVE or FAILED if the string is not found.

If no response is received within the configured interval (the default is five seconds), the ServerIron ADX sends an RST and retries the health check. After the configured number of retries (the default is two retries), if the server still does not respond, the ServerIron ADX marks the server port FAILED.

A scripted health check can also be part of a health-check policy. In this case, the scripted health check checks the health of a configured port in the policy. The health-check policy can be evaluated to true or false depending on the response from the server.

Follow the steps given below to configure a scripted health check.

1. Configuring a port profile

2. Configuring a matching list

3. Binding the matching list to the real server

Configuring a port profilePort profiles enable you to globally configure the attributes for individual TCP/UDP ports. A scripted health check will not work on a TCP port that does not have a profile, because the ServerIron ADX assumes any port without a profile is a UDP port, and will perform UDP health checking on the port. To use a scripted health check on a TCP port, you must create a port profile and explicitly identify the port as a TCP port.

The following commands configure a port profile for port 12345 and specify that the port is a TCP port. The no-fast-bringup command is necessary because it prevents the ServerIron ADX from marking a port ACTIVE until it passes both Layer 4 and Layer 7 health checks.

ServerIronADX(config)#server port 12345ServerIronADX(config-port-12345)#tcpServerIronADX(config-port-12345)#no-fast-bringup


Syntax: tcp | udp [keepalive interval retries]

Syntax: no-fast-bringup



Configuring a matching listThe selection criteria used in a content verification health check is specified in a matching list that is bound to one or more real servers. The syntax used for creating a matching list for scripted health checks is the same as that used for creating a matching list for HTTP content verification health checks.

The following is an example of a matching list that will mark a port ACTIVE if the string “FTP service” is found in the response from the real server. If this text is not found, the port on the real server is marked FAILED.

ServerIronADX(config)#http match-list m1ServerIronADX(config-http-m1-m1)#up simple "FTP service"ServerIronADX(config-http-m1-m1)#default downServerIronADX(config-http-ml-m1)#exit

In this example, the default down command causes the port on the real server to be marked FAILED if the selection criteria is not found in the response from the server.

For information on the command syntax, refer to “Configuring HTTP content matching lists” on page 266.

Binding the matching list to the real serverTo enable the scripted health check on the ServerIron ADX, you bind the matching list to one or more real servers. For example, to bind matching list m1 to real server R, enter commands such as the following.

ServerIronADX(config)#server real R 10.10.10.50ServerIronADX(config-rs-R)#port 12345 content-check m1

Syntax: port portnum content-check matching-list-name

The portnum variable is a non-well-known port. You cannot specify a well-known port for a scripted health check.

The matching-list-name variable is a previously configured matching list. If the matching-list-name does not refer to an existing matching list, the port on the real server is marked FAILED when the health check is performed.

Using a scripted health check in a health-check policy

A scripted health check can be used in a health-check policy. A health-check policy is a group of one or more health checks attached to a real server port. When the scripted health check checks the health of a destination port specified in the policy, the health-check policy can be evaluated to true or false depending on the response from the server.

To use a scripted health check with a health-check policy, you configure a matching list, then configure the health-check policy.

For example, when the following matching list is used with a health-check policy, it will evaluate the policy to true if the string “FTP service” is found in the response from the real server. If this text is not found, the policy is evaluated to false.

ServerIronADX(config)#http match-list m1ServerIronADX(config-http-m1-m1)#up simple "FTP service"ServerIronADX(config-http-m1-m1)#default downServerIronADX(config-http-ml-m1)#exit



The default down command causes the policy to be evaluated to false if the selection criteria is not found in the response from the server. If the real server responds to the health check with an RST, the policy is evaluated to true or false depending on what was specified in the default statement in the matching list.

Configuring a health check policyThe following commands create a health check policy for TCP port 1234 on VIP 10.10.10.10. Matching list m1 is bound to this policy.

ServerIronADX(config)#healthck check1 tcpServerIronADX(config-hc-check1)#dest-ip 10.10.10.10ServerIronADX(config-hc-check1)#port 1234 content-check m1ServerIronADX(config-hc-check1)#l7-check

Syntax: [no] healthck element-name protocol }

Syntax: [no] dest-ip { ipv4-addr | ipv6-addr }



Syntax: [no] port portnum content-check matching-list-name

Syntax: [no] l7-check

Note that the dest-ip ipv4-addr | ipv6-addr command must be the first command entered for a health-check policy. If this is not the first command entered for the policy, an error message is displayed.

If the matching-list-name variable does not refer to an existing matching list, the policy is evaluated to false.

The l7-check command is required to ensure that the ServerIron ADX performs a Layer 7 health check. If this command is omitted, the ServerIron ADX performs only a Layer 4 health check, and not the scripted health check.

Scripted health check enhancement on real servers

When the port port-name command is configured with the content-check send option to send a string to the server, the ServerIron ADX establishes a TCP connection, and on receiving a SYN-ACK, sends the configured string to the server. The device then waits for the server to send ASCII text and then brings the server port up or down, based on the configured match-list policy.

In the following example, the ServerIron ADX sends a SYN packet to server 10.10.1.31, port 1234. On receiving a SYN-ACK from the server, the ServerIron ADX sends a TCP packet with the data "how are you". The ServerIron ADX then waits for the server. In the data of the TCP packets sent by the server, the ServerIron ADX will look for the pattern "good". If found, the ServerIron ADX marks the real server r1 port 1234 as UP; otherwise, it will mark the port as DOWN.

ServerIronADX(config)#server real r1 10.10.1.31ServerIronADX(config-rs-r1)#port 1234 keepaliveServerIronADX(config-rs-r1)#port 1234 content-check m1ServerIronADX(config-rs-r1)#port 1234 content-check send "how are you"ServerIronADX(config-rs-r1)#exitServerIronADX(config)#http match-list m1ServerIronADX(config-http-ml-m1)#up simple goodServerIronADX(config-http-ml-m1)#default down

Syntax: [no] port port-name content-check match-list-name



Syntax: [no] port port-name content-check send "string"

NOTEThe l7-check command must be enabled in order for the ServerIron ADX to send the script. If the l4-check command is configured, the ServerIron ADX will establish a TCP connection and then send an RST.

Binary scripted health checkThe scripted health check feature allows ServerIron to complete 3-way TCP handshake followed by sending an ASCII string and waiting for an appropriate response before marking real server health. If the customer is running an application that can not interpret data in ASCII format, this methodology will not help.

Binary scripted heath check allows the application switch to send binary data (carray format) after doing a 3-way TCP handshake with the backend server. The ServerIron ADX would then mark the health of the server as pass or failed depending on the response content match (again in carray format). This feature is implemented using the content-check-array option within the real server port command as shown in the following sample configuration.

ServerIronADX(config)#server real rs1 10.1.1.1ServerIronADX(config-rs-rs1)#port 1111 content-check-carray m1 ServerIronADX(config-rs-rs1)#port 1111 content-check-carray send “0xe1,0xe2,0xe3, 0xe4”ServerIronADX(config-rs-rs1)#port 1111 keepaliveServerIronADX(config)#http match-list m1ServerIronADX(config-http-m1-m1)#default downServerIronADX(config-http-m1-m1)#up simple 0xca,0xcb,0xcd,0xce

Syntax: [no] port port-name content-check-carray match-list-name

The port-name variable defines the port where the binary scripted health check is performed.

The match-list-name variable defines the name of the matching list used in the binary scripted health check.

Syntax: [no] port port-name content-check-carray send Carray-data

The port-name variable defines the port where the binary scripted health check is performed.

The Carray-data variable defines the binary data in C array format used in the binary scripted health check. The maximum number of characters supported is 2000.

NOTESending binary data after a 3-way handshake is not mandatory.

Scripted health check for UDP ports

The scripted health check feature enhances the TrafficWorks software to perform customizable scripted health checks for UDP protocol. in addition to the current TCP protocol, this feature is available on any out-of-band port and is able to use the existing L7 content check features.

The ServerIron ADX currently supports scripted health-checks on TCP ports. This feature adds support for scripted health-checks on UDP ports.


Boolean health checks4

When scripted health-check is configured on a UDP port, the ServerIron ADX will send out a UDP packet with the content-check-send data if configured; otherwise, it will send out a UDP packet. Then it expects a UDP reply with ASCII content and will do the content-check on the data received. It will mark the port UP or DOWN according to the configuration in the match-list.

If an ICMP message is received, then the port will be brought down.


There is no new CLI added for this feature. The CLI is the same as that used for scripted health-checks for TCP ports. Previously the CLI was restricted to TCP ports, while now that restriction has been removed.

ServerIronADX(config)#server real r1 10.10.1.31ServerIronADX(config-rs-r1)#port 1234 keepaliveServerIronADX(config-rs-r1)#port 1234 content-check m1ServerIronADX(config-rs-r1)#port 1234 content-check send "how are you"ServerIronADX(config)#http match-list m1ServerIronADX(config-http-ml-m1)#up simple goodServerIronADX(config-http-ml-m1)#default down

In the above example, the ServerIron ADX will send and UDP packet containing the ASCII string "how are you." On receiving the reply, ServerIron ADX will search for the string "good." If found, it will mark port 1234 UP, otherwise it will mark the port DOWN.

Boolean health checks

Boolean health-check policiesYou can configure a group of Layer 4 and Layer 7 health checks as a health-check policy and associate the group with a specific application port on a real server.1 Health-check policies enable you to assess the health of any application port using the health-check mechanisms for ports well-known to the ServerIron ADX. In addition, health-check policies let you use multiple checks with different parameters and base a port’s health on successful completion of all or any one of the individual checks in the policy.

NOTEThe ServerIron ADX does not support Boolean health checks with Direct Server Return (DSR).

Depending on the conditions you specify when you configure a health-check policy, the ServerIron ADX will bring the application port on a server down in one of the following cases:

• Any one of the servers fails its health check (individual health checks combined using AND condition) – In this case, all servers in the policy must pass their health checks. Otherwise, the ServerIron ADX considers all of the servers to have failed the health checks and brings down the application on all servers that are checked by the policy.

1. Real servers include those added using the server real-name command and those added using the server remote-name command. Generally, both types of servers are referred to as real servers. An application port is a port that uses the TCP or UDP protocol. You associate health-check policies with TCP or UDP ports on the real servers (not with physical ports on the servers).


Boolean health checks 4

• All of the servers fail their health checks (individual health checks combined using OR condition) – In this case, an application port remains up as long as at least one of the servers checked by the policy passes its health check.

For finer control, you can combine OR and AND conditions.

Health-check policyHealth-check policies consist of element-action expressions and logical expressions.

• An Element-action expression consists of the IP address of the server, the Layer 4 protocol (TCP or UDP), and the application port on the server. For some applications, the element-action expression can also include Layer 7 application-specific health check information.

• A Logical expression is a set of element-action expressions joined by the Boolean operators OR, AND or NOT.

- To create a health-check policy that is successful if at least one of the applications passes its health check, use OR.

- To configure a health-check policy that is successful only if the ServerIron ADX receives a successful reply from all servers and application ports in the policy, use the operator AND.

- To configure a health-check policy that is successful if none of the elements responds to the health check, use the operator NOT.

You can use the same element-action expressions in multiple logical expressions if desired. You can configure up to 254 health-check policies.

Follow the steps given below to use a health-check policy.

1. Configure the element-action expressions.

2. Configure the health-check policy using element-action expressions and logical expressions joined by the operators AND or OR or NOT.

3. Attach logical expressions to application ports on specific real servers. A health check policy does not take effect until you attach it to an application port on a server.

NOTEA health-check policy does not take effect (begin sending health check packets) until you attach the policy to an application port on a real server.

Configuring boolean health checkA health-check policy consists of one or more element-action expressions. When a logical expression contains multiple element-action expressions, the policy also contains the logical operator AND or OR or NOT.

You can use a health-check policy as an element-action expression in another policy.

To configure a health-check policy, enter commands such as the following.

ServerIronADX(config)#healthck "httpsrvr" booleanServerIronADX(config-hc-httpsrvr)#and "check1" "check2"


Boolean health checks4

These commands configure a health-check policy that uses the element-action expressions "check1" and "check2". Because the AND operator is used, the real servers in both "check1" and "check2" must reply successfully for the health check to be successful. If only one of the servers replies, the health check is unsuccessful and the ServerIron ADX stops using all the server application ports in the health-check policy "httpsrvr".

Syntax: [no] healthck "policy-name" boolean

Syntax: and | or "element-name" "element-name"

The policy-name variable specifies the name of the health-check policy. The name can be up to 20 characters long. The name cannot contain blanks.

The and or or command specifies a logical operator in the health-check policy. You can enter two element-action expressions along with the logical operator and, or, or not.

• If you specify and, the policy evaluates to true only if all elements (IP addresses) respond to the health check.

• If you specify or, the policy is true if at least one of the elements responds to the health check.

• If you specify not, the policy is true if none of the elements responds to the health check.

If you are configuring a boolean UDP health check policy, define the static next hop MAC address along with a VLAN ID for on that link; otherwise, the ServerIron ADX cannot learn the next-hop-mac-address of that link. Enter commands such as the following to define a static next-hop-mac-address and a VLAN-ID.

ServerIronADX(config-link-link3)#next-hop-mac-address 00e0.5208.dd8e vlan-id 40

The address 00e0.5208.dd8e is the MAC address of Link3's access router interface. The vlan-id 40 is the ServerIron ADXs interface, that is used to connect Link3's access router is in VLAN 40

Syntax: next-hop-mac-address mac-address vlan-id vlan#

Using a nested health-check policy

If you want to use a single health-check policy to test more than two IP addresses, configure health-check policies for all the IP addresses, and use them in another health-check policy. For example, to create a health-check policy that tests four IP addresses, enter commands such as the following.

ServerIronADX(config)#healthck check1 tcpServerIronADX(config-hc-check1)#dest-ip 10.10.10.50ServerIronADX(config-hc-check1)#port httpServerIronADX(config-hc-check1)#healthck check2 tcpServerIronADX(config-hc-check2)#dest-ip 10.10.10.20ServerIronADX(config-hc-check2)#port httpServerIronADX(config-hc-check2)#healthck check3 tcpServerIronADX(config-hc-check3)#dest-ip 10.10.10.30ServerIronADX(config-hc-check3)#port httpServerIronADX(config-hc-check3)#healthck check4 tcpServerIronADX(config-hc-check4)#dest-ip 10.10.10.40ServerIronADX(config-hc-check4)#port http

The commands above configure four element-action expressions, one for each of four servers. The following commands configure two health-check policies, each of which contains two of the element-action expressions.

ServerIronADX(config-hc-check4)#healthck nested1 booleanServerIronADX(config-hc-nested1)#or check1 check2


Miscellaneous health check settings 4

ServerIronADX(config-hc-nested1)#healthck nested2 booleanServerIronADX(config-hc-nested2)#or check3 check4

The following command creates a health-check policy that contains the two policies configured above. The result is a single health-check policy for all four IP servers.

ServerIronADX(config-hc-nested2)#healthck checkall booleanServerIronADX(config-hc-checkall)#or nested1 nested2

In this example, the OR logical operator is used in all the policies. Therefore, the "checkall" health check is successful if at least one of the four servers responds. To create more restrictive policies, you can use the AND logical operator. For example, if the AND operator is used in this configuration instead of OR, the health check is successful only if all four servers respond.

You also can combine policies that use AND with policies that use OR in nested health-check policies.

Miscellaneous health check settings

Basing an alias port’s health on the health of its master portBoth SLB traffic handling and SLB state computation use the alias port state. You can base an alias port’s health on the health of one of the following TCP ports:

• FTP – port 21 (ports 20 and 21 both are FTP ports but on the ServerIron ADX, the name “FTP” corresponds to port 21)

• HTTP – port 80

• IMAP4 – port 143

• LDAP – port 389

• MMS – port 1755

• NNTP – port 119

• PNM – port 7070

• POP3 – port 110

• RTSP – port 554

• SMTP – port 25

• SSL – port 443

• TELNET – port 23

You cannot base an alias port’s health on the health of a UDP port or a port that is not well-known to the ServerIron ADX.

NOTEThe health checks for the alias ports must be enabled. Otherwise, the ServerIron ADX will not check the master port’s state, and the alias port will not go down when the master port goes down.


Miscellaneous health check settings4

If you want to forward SLB traffic to an alias port only when the master port is ACTIVE, you can configure the ServerIron ADX to base the alias port state on the master port state. To configure an alias port’s health to be based on its master port’s health, edit the alias port’s profile by entering commands such as the following.

ServerIronADX(config)#server port 8080ServerIronADX(config-port-8080)#tcp keepalive use-master-state

Syntax: [no] tcp keepalive use-master-state

The command is entered at the port profile level.

NOTEWhen you configure this command, the operational state of the alias port and master port are the same. However, they can differ if the master port is disabled administratively and the alias port is not disabled. In this case, no health checks is sent for the alias port and the ServerIron ADX cannot detect a port failure. This is a misconfiguration and Brocade advises you to disable the alias port whenever the master port is disabled. The same is true when the master port is unbound or deleted with the alias port still has the virtual port binding.

NOTEThe SLB state of a virtual port is also referred to as SLB healthy or VIP healthy of virtual ports.

Basing a port’s health on the health of another portYou can configure the ServerIron ADX to base the health of a port that is not well-known to the ServerIron ADX on the health of one of the following ports that are well-known to the ServerIron ADX:

• DNS (port 53)

• FTP (port 21). Ports 20 and 21 both are FTP ports but on the ServerIron ADX, the name “FTP” corresponds to port 21.

• HTTP (port 80)


• LDAP (port 389)

• POP3 (port 110)

• NNTP (port 119)

• SMTP (port 25)

• TELNET (port 23)

To base a port’s health on the health of another port, enter a command such as the following.

ServerIronADX(config-port-1234)#tcp keepalive port 80

Syntax: tcp | udp keepalive port TCP/UDP-portnum

The command in this example configures the ServerIron ADX to base the health of port 1234 on the health of port 80 (HTTP). If the health of port 80 changes, the ServerIron ADX applies the change to port 1234.

NOTEYou cannot base the health of a port well-known to the ServerIron ADX on the health of another port, whether the port is well-known or not well-known.



Reassign thresholdThe reassign threshold specifies the number of contiguous inbound TCP-SYN packets a real server can fail to respond to before the ServerIron ADX changes the application state to FAILED and the server state to TEST. The server and application states are described in “Server and application port states” on page 240.

The value of an application's reassign counter is reset to 0 when the ServerIron receives a TCP SYN ACK from the application. No other type of traffic can clear this field. This reassign counter can be seen with the show server real name or ip detail command where name or ip is the real server's ASCII name or IP address.

If a real server seems to be triggering the reassign threshold too frequently, you can increase the reassign threshold. The reassign threshold is disabled by default. To modify the reassign threshold to 215, enter a command such as the following:

ServerIronADX(config)#server reassign-threshold 215

Syntax: server reassign-threshold threshold-value

The range of values for the threshold-value variable is 6 through 4000. If you do not specify a number, the ServerIron ADX assigns a default threshold value of 20.

NOTEIt is possible to take a service down without triggering the reassign threshold. For example, if no new TCP SYN packets are being sent to a real server that has its application disabled, the real server will not fail to respond to enough consecutive TCP SYNs to meet the reassign threshold. As a result, the ServerIron indicates the real server and the service are ACTIVE when in fact they might have been disabled.

NOTEThe reassign threshold does not apply to servers in SwitchBack (Direct Server Return) configurations. The reassign counter is not incremented in such configurations. In a SwitchBack configuration, traffic from the real server does not pass back through the ServerIron ADX. As a result, the ServerIron ADX cannot monitor the TCP SYN ACKs from the server. Refer to “Configuring Direct Server Return” on page 84.

NOTEThe ServerIron ADX does not try to reassign the client’s request to another server if you configure the application port to be sticky. The sticky option configures the ServerIron ADX to override load-balancing and send all client requests for the application to the same server during a given session.

NOTEIf a real server seems to be triggering the reassign threshold too frequently, you can increase the reassign threshold. This is a global parameter.



Preventing state flapping

You can prevent state flapping caused by the reassignment counter.

By default, the ServerIron ADX brings an application port down if the port's reassignment count exceeds the reassign threshold. If an application port's reassign counter exceeds the reassign threshold, the ServerIron ADX marks the port failed. Once the port is marked failed, the port can be re-activated as a result of a successful health check on the port.

In some networks, the reassignment counter can cause needless state flapping of application ports. This occurs if the network conditions cause the counter to frequently reach the threshold and cause the ServerIron ADX to mark otherwise healthy applications as failed. The applications will remain unavailable for the amount of time it takes the ServerIron ADX to send health checks, interpret the results, and activate the application ports in response to successful results.

NOTEThe reassignment count applies to the total number of contiguous (back-to-back) unanswered SYNs from all clients who have sent SYNs to the server.

To prevent state flapping caused by the reassignment counter, enter the following command.

ServerIronADX(config)#server no-reassign-count

When you enter this command, the ServerIron ADX will stop incrementing the reassignment counters for real server applications.

Syntax: [no] server no-reassign-count

FastCacheIn typical TCS configurations, the ServerIron ADX uses cache responses that flow back through the ServerIron ADX as a means to determine the health of the cache server.

When the ServerIron ADX receives cache responses to client requests sent to the cache by the ServerIron ADX, the ServerIron ADX knows that the cache server is healthy. However, if the cache server does not respond to client requests, the ServerIron ADX assumes that the cache server is down and stops sending client requests to the cache server.

Some configurations might require responses from a cache server to select a path that does not return through the ServerIron ADX. For example, if a cache server supports only one default path and that path is to a gateway router, not to the ServerIron ADX, the cache server might send responses to the clients through the default gateway instead of through the ServerIron ADX. In this case, the ServerIron ADX assumes that the cache server has stopped responding even though the cache server is still working normally.

You can override health checking on an individual server basis by enabling FastCache. This feature allows the ServerIron ADX to continue using a cache server even if the server does not send responses to client requests back through the ServerIron ADX. When you enable FastCache on a cache server, the ServerIron ADX continues to send client requests to the cache server even if the server does not respond through the ServerIron ADX.



Globally disabling all health-check policiesYou can easily disable all the health-check policies configured on the ServerIron ADX. To do so, enter the following command at the global CONFIG level of the CLI.

ServerIronADX(config)#no server l4-check

NOTEThis command also disables the TCP and UDP Layer 4 health checks for all applications that are not associated with a health-check policy.

Syntax: [no] server l4-check

To re-enable the health-check policies, enter the following command.

ServerIronADX(config)#server l4-check

NOTEThe server l4-check command does not enable a policy if its element-action expressions contain the disable command. In this case, the policy remains disabled.

Health checking for real servers in other subnetsThe ServerIron ADX must be able to receive the real server’s response to a health check in order to assess the success of the health check. In topologies where reply traffic from a real server is guaranteed to pass through the ServerIron ADX, the ServerIron ADX is able to receive replies to the health checks.

However, if the topology is such that the ServerIron ADX and real servers are in different subnets or the server reply is not guaranteed to pass back though the ServerIron ADX, you might need to use source NAT and configure a source IP address. Source NAT and source IP addresses allow the ServerIron ADX to have multiple subnet identities. Generally, the ServerIron ADX is a member of only one subnet, the subnet that contains the ServerIron ADX’s management IP address. You can place the ServerIron ADX into up to eight additional subnets by enabling source NAT and adding source IP addresses to the ServerIron ADX.

Normally, the ServerIron ADX uses its management IP address as the source address for health check packets. When you enable source NAT and add a source IP address, the ServerIron ADX uses the source IP address as the source for the health check packets. Thus, when the real server replies, the reply is addressed to the source IP address instead of the ServerIron ADX’s management IP address.

For an example of how to configure source NAT and source IP addresses, refer to “Web hosting with ServerIron ADX and real servers in different subnets” on page 534.

Best path to a remote server

NOTEBrocade recommends that you use this feature whenever the ServerIron ADX is in the direct path between the remote server and the default gateway.



When the ServerIron ADX sends a health check to a remote server, the ServerIron ADX sends the health check through the default gateway, because the remote server’s subnet is different from the subnet of the ServerIron ADX’s management IP address. In some topologies, the ServerIron ADX’s default gateway is not the most direct path to the remote server. Figure 26 shows an example.

FIGURE 26 Health check of remote server – learned MAC address is not used

In this example, the ServerIron ADX sends the health check through its default gateway. The default gateway sends the health check back to the ServerIron ADX, because Router R1’s route to the remote server lists the ServerIron ADX as the next hop. Despite the unnecessary trip through the default gateway, the health check still reaches the remote server. However, if you want to eliminate unnecessary hops, you can enable the ServerIron ADX to learn the MAC address from which the remote server’s health check reply is received, and send subsequent health checks directly through that MAC address. Figure 27 shows the simplified health check process.

FIGURE 27 Health check of remote server – learned MAC address is used

To enable the ServerIron ADX to use learned MAC addresses for sending health checks to remote servers, enter the following command.

ServerIronADX(config-rs-remote1)#use-learned-mac-address

Syntax: [no] use-learned-mac-address

NOTEThis command does not apply to local servers. Because local servers are attached at Layer 2, the ServerIron ADX does not need to use a gateway or otherwise route the health check to the server.

Handling traffic initiated from remote serverUnder normal conditions, traffic is always intiated from a client and return traffic is processed by looking up the session table. However, a real server may have to initiate traffic to a client in some complex protocols such as Active FTP. The ServerIron ADX checks the source MAC to handle the traffic initiated from the remote server. The ServerIron ADX may drop the return traffic in some topologies like VRRP and VRRP-E redundant network topologies.



In VRRP, the router may use the source MAC of the physical interface instead of the virtual interface for the real server initiated traffic. This includes the data connection from the remote server back to the client, which is an expected behavior for VRRP. However, for the ServerIron ADX to identify traffic from the remote server, it has to come from the same source MAC as the one installed in the show arp or show server real server-name output. The ServerIron ADX expects the return traffic from the same VRRP vip MAC instead of the physical interface MAC, and if this is not the case, it will drop the return traffic.

To enable the ServerIron ADX to check the source IP instead of source MAC to handle the traffic from a remote server, enter the following command:

ServerIronADX(config)#server identify-server-by-ip

Syntax: [no] server identify-server-by-ip

Minimum healthy real servers under VIP portThe minimum healthy servers feature allows a VIP port to handle traffic only if the a configured number of real server ports bound to the VIP port are healthy and UP. This would allow virtual servers to stay down unless they have enough server capacity to handle the load.


The command to turn on minimum healthy servers feature is under virtual server configuration.

ServerIronADX(config)#server virtual-name-or-ip v1 10.1.1.1ServerIronADX(config-virtual-server-v1) port 80ServerIronADX(config-virtual-server-v1) port 80 minimum-servers 2ServerIronADX(config-virtual-server-v1) bind http rs1 http rs2 http rs3 http rs4 http

The VIP will not answer connections on port http until at least 2 of the real or remote servers bound to port http are UP.

Server port bring-up retriesThe ServerIron ADX currently brings a port up after it passes the configured health-check. This feature allows user to configure retries for bringup, so that the ServerIron ADX brings up a port only after the configured number of retries have passed. The real server port will need to pass the configured number of checks before coming up.


The command to turn on server port bring-up enhancement feature is under port profile configuration.

ServerIronADX(config)#server port 80ServerIronADX(config-port-80) bringup-retries 10

ServerIron ADX will now bring port 80 up only after it has passed num number of health-checks. Previously port 80 would have been marked as up after the first time it passes a health-check.



Layer 4 and Layer 7 port bring-up intervalThe ServerIron ADX brings a port up after it passes the configured health-check. The ServerIron ADX allows you to configure a maximum time interval, during which the ServerIron ADX will wait for the server to respond before marking the bringup attempt to fail and retrying. The Layer 4 bringup interval is the maximum time that the ServerIron ADX waits for a SYN-ACK after sending the SYN to the server. To configure the Layer 4 bring-up interval, use the l4-bringup-interval command.

The Layer 7 bring-up interval is the maximum time that the ServerIron ADX waits for a Layer-7 response from the server over a TCP connection. To configure the Layer 7 bring-up interval, use the l7-bringup-interval command.

ServerIronADX(config)#server port 80ServerIronADX(config-port-http)#l4-bringup-interval 10ServerIronADX(config-port-http)#l7-bringup-interval 10

Syntax: [no] l4-bringup-interval seconds

Syntax: [no] l7-bringup-interval seconds

The seconds variable is the number of seconds for the wait time. Enter a number from 1 to 255.

These commands are also available under port-profile-range configuration mode.

Slow-start mechanismWhen the ServerIron ADX begins sending client requests to a real server that has recently gone online, it allows the server to ramp up by using the slow-start mechanism. The slow-start mechanism allows a server (or a port on the server) to handle a limited number of connections at first and then gradually handle an increasing number of connections until the maximum is reached.

The ServerIron ADX uses two kinds of slow-start mechanisms:

• The non-configurable server slow-start mechanism applies to a real server that has just gone online

• The configurable port slow-start mechanism applies to individual TCP application ports that have just been activated on a real server

Overview

The ServerIron ADX uses the server slow-start mechanism to adjust the maximum number of connections that can be established for a real server that has just gone online. The ServerIron ADX begins with a connection limit that is lower than the maximum configured value (which is one million by default) and gradually increases this connection limit until the maximum configured value is reached.

The server slow-start mechanism is especially useful when least connections is the distribution predictor. Without the server slow-start mechanism, a server that is just brought online could receive all the new connections in a flurry, which could bring the server down. Many servers cannot handle more than 2,000 new connections per second.



NOTEThe server slow-start mechanism is always applied to all real servers when they are brought online. Unlike the slow-start mechanism for individual ports, described in the next section, the server slow-start mechanism is not configurable.

The two graphs in Figure 28 illustrate how the server slow-start mechanism ramps up the connections for a real server during the 30-second slow-start period. The graph on the left shows the rate at which the number of connections increases over the slow-start period. The graph on the right shows how the maximum number of connections that the ServerIron ADX allows for the real server increases over the slow-start period.

FIGURE 28 Slow-start mechanism for a real server

The graph on the left shows the rate at which the ServerIron ADX allows connections for a given real server, as follows:

• From the time the real server is brought online from 10 seconds to 20 seconds, the ServerIron ADX allows a max-connection rate of 10 times the elapsed time. During this period, the ServerIron ADX increases up to 10 new connections every second on the real server.

• At 21 seconds,the ServerIron ADX allows a max-connection rate of 20 times the elapsed time. The ServerIron ADX increases the connections to 420 and from 22 seconds to 29 seconds, the ServerIron ADX allows up to 20 new connections every second.

• At 30 seconds, the maximum number of connections is reached.

The graph on the right shows how the maximum number of connections allowed for the real server increases over the 30-second slow-start period.



Table 21 lists the maximum number of connections a real server can have during each second of the slow-start period.

When the slow-start period ends after 30 seconds, the maximum number of connections a real server can have is determined by the max-conn setting for the real server and is one million connections by default.

NOTEWhen you disable and re-enable a real server, the ServerIron ADX will go through the slow-start mechanism for the server if it is not disabled. When you disable and re-enable a real-server port, the ServerIron ADX does not go through the port level slow-start mechanism.

Port slow-start mechanism

When individual TCP application ports on a real server are activated, they are allocated connections using the port slow-start mechanism, which works differently from the server slow-start mechanism described in the previous section.

When a port on a real server becomes active, the ServerIron ADX applies the default slow-start mechanism to regulate how quickly connections for the port are established. In addition, you can set up a user-configured slow-start mechanism that regulates how quickly connections are established for specific ports on specific real servers. The following sections explain how the default slow-start mechanism works, along with how to set up a user-configured slow-start mechanism and apply it to a port on a real server.

TABLE 21 Maximum number of connections for a real server

Seconds after going online Max. connections Seconds after going online Max. connections

1 10 16 160

2 20 17 170

3 30 18 180

4 40 19 190

5 50 20 200

6 60 21 420

7 70 22 440

8 80 23 460

9 90 24 480

10 100 25 500

11 110 26 520

12 120 27 540

13 130 28 560

14 140 29 580

15 150 30 Maximum



Default port slow-start mechanismBy default, when a port is activated, the ServerIron ADX gives it 60 seconds of warm-up time. Over this period, the ServerIron ADX gradually increases the number of connections it allows for the port. The default slow-start mechanism is always applied to all ports when they are first brought online, unless they are configured to use a user-configured slow-start mechanism.

The two graphs in Figure 29 illustrate how the default slow-start mechanism ramps up the connections for a port on a real server. The graph on the left shows the rate at which the number of connections increases over the slow-start period. The graph on the right shows how the maximum number of connections the ServerIron ADX allows for the port on the real server increases over the slow-start period.

FIGURE 29 Default slow-start mechanism for a port

The graph on the left shows the rate at which the ServerIron ADX allows connections for a given port on a real server, as follows:

• At the time the port is activated, the ServerIron ADX allows 10 connections. Then, up to 10 seconds, the ServerIron ADX allows the port up to 10 new connections every second.

• From 10 seconds to 20 seconds, the ServerIron ADX allows up to 20 new connections every second.







• After 60 seconds, the connection flow control delivered by the slow-start mechanism ends, and the ServerIron ADX allows up to the maximum number of connections for the port on the server. The maximum number of allowed connections for a real server is set by the max-conn command; this maximum is one million connections by default.

The graph on the right shows how the maximum number of connections allowed for the port on the real server increases over the slow-start period.

Table 22 lists the maximum number of connections a port can have at 10-second intervals.

When the slow-start period ends after 60 seconds, the maximum number of connections that a port on a real server can have is determined by the max-conn setting for the real server and is one million connections by default.

Setting up a user-configured port slow-start mechanismYou can configure how quickly the ServerIron ADX ramps up a particular port on a particular real server by setting up a user-configured slow-start mechanism. Unlike the default port slow-start mechanism, which applies to all ports on all real servers, a user-configured slow-start mechanism is applied to a specific port on a specific real server.

A user-configured slow-start mechanism sets the rate at which the ServerIron ADX allows connections for a port over two configurable intervals (which comprise the slow-start period), along with a limit for the total number of connections that the port on the real server can have during the time the server is active.

Setting up a user-configured slow-start mechanism consists of the following two steps.

1. Setting up a slow-start list for a port

2. Applying the slow-start list to a port on a real server

Setting up a slow-start list for a portTo set up a slow-start list for port 80 (HTTP), enter commands such as the following.

ServerIronADX(config)#server port 80ServerIronADX(config-port-80)#slow-start 101 10 30 20 30 600ServerIronADX(config-port-80)#exit

Syntax: slow-start list-id rate1 interval1 rate2 interval2 max-connections

TABLE 22 Maximum number of connections for a port

Seconds after port activated Max. connections

10 110

20 310

30 610

40 1,010

50 1,510

60 2,510



In the slow-start command, the list-id variable specifies the slow-start list. This variable can be a number from 1 through 1000000. When you apply the slow-start list to a port on a real server, you refer to the slow-start list by the variable specified here. You can create multiple slow-start lists for a given port and assign them each an ID number.

The rate1 variable specifies the number of connections per second allowed for the port during the first interval. This variable can be a number from 1 through 1000000. From the time the port is activated until the end of the first interval, the ServerIron ADX allows the port on the real server to receive up to this number of new connections every second.

The interval1 variable specifies the length of the first interval in seconds. This variable can be a number from 1 through 1000000.

The rate2 variable specifies the number of connections per second allowed for the port during the second interval. Allowed values are from 1 through 1000000. From the end of the first interval until the end of the second interval, the ServerIron ADX allows the port on the real server to receive up to this number of new connections every second.

The interval2 variable specifies the length of the second interval in seconds. This variable can be a number from 1 through 1000000. The number of seconds in the first interval plus the number of seconds in the second interval are equal to the slow-start period. In this example, value specified for the interval1 variable is 30 seconds, and the value specified for the interval2 value is 30 seconds, so the slow-start period is 60 seconds.

The max-connections variable sets a ceiling for the number of concurrent connections allowed for the port during the time the server is active. This can be a number from 1 through 1000000. No more than this number of connections can be established for the port on the real server where this slow-start mechanism is applied.

Applying the slow-start list to a port on a real serverAfter you have created a slow-start list, you apply it to a port on a real server, by entering commands such as the following.

ServerIronADX(config)#server real-name rs1 192.168.1.1ServerIronADX(config-rs-rs1)#port httpServerIronADX(config-rs-rs1)#port http slow-start 101ServerIronADX(config-rs-rs1)#exit

Syntax: port port slow-start list-id

The port http slow-start 101 command binds slow-start list 101 (defined for port 80 above) to port 80 (HTTP) on real server rs1.



Using the slow-start list defined above, the two graphs in Figure 30 illustrate how a user-configured slow-start mechanism ramps up the connections for a port on a real server. The graph on the left shows the rate at which the number of HTTP connections increases over the slow-start period. The graph on the right shows how the maximum number of HTTP connections the ServerIron ADX allows for real server rs1 increases over the slow-start period.

FIGURE 30 Example of a user-configured slow-start mechanism for port 80 (HTTP) on a real server

The graph on the left shows the rate at which the ServerIron ADX allows HTTP connections for real server rs1, as follows:

• From the time port 80 (HTTP) on real server rs1 is activated until 30 seconds afterwards (until the end of interval 1), the ServerIron ADX allows the real server up to 10 (rate 1) new HTTP connections every second.

• From 30 seconds to 60 seconds (until the end of interval 2), the ServerIron ADX allows up to 20 (rate 2) new HTTP connections every second.

• After 60 seconds (interval 1 plus interval 2), the slow-start period ends, and the ServerIron ADX allows up to the maximum number of connections for the server set by the max-connections variable in the slow start list.



The graph on the right shows how the maximum number of possible HTTP connections for real server rs1 increases over the slow-start period:

• Ten seconds after going online, the maximum number of HTTP connections real server rs1 can have is 300: a maximum of 10 (rate 1) new HTTP connections per second for 30 (interval 1) seconds equals 300 total HTTP connections for real server rs1.

• After 30 seconds, the maximum number of HTTP connections for real server rs1 increases by 20 (rate 2) connections per second, until 600 HTTP connections (the ceiling specified by the max-connections variable in the slow-start list) is reached. This ceiling of concurrent 600 HTTP connections applies for the entire time the server is active; the ServerIron ADX allows the server no more than this number of concurrent HTTP connections.

Applying a user-configured slow-start mechanism to multiple portsTo apply a user-configured slow-start mechanism to more than one port, create slow-start lists for each port and apply them to ports on one or more real servers. For example, to configure a slow-start mechanism for HTTP (port 80) and SSL (port 443), enter commands such as the following.

ServerIronADX(config) #server port 80ServerIronADX(config-port-80)#slow-start 100 10 30 20 30 600ServerIronADX(config-port-80)#slow-start 101 20 30 40 30 1500ServerIronADX(config-port-80)#exitServerIronADX(config)#server port 443ServerIronADX(config-port-80)#slow-start 101 20 60 40 120 2400ServerIronADX(config-port-80)#exitServerIronADX(config)#server real-name rs2 192.168.1.2ServerIronADX(config-rs-rs2)#port httpServerIronADX(config-rs-rs2)#port http slow-start 100ServerIronADX(config-rs-rs2)#exitServerIronADX(config)#server real-name rs3 192.168.1.3ServerIronADX(config-rs-rs3)#port httpServerIronADX(config-rs-rs3)#port http slow-start 101ServerIronADX(config-rs-rs3)#port sslServerIronADX(config-rs-rs3)#port ssl slow-start 101ServerIronADX(config-rs-rs3)#exit

The commands create two slow-start lists for port 80 (HTTP) and one for port 443 (SSL). Slow-start list 100 for port 80 is applied to the HTTP port on real server rs2. Slow-start list 101 for port 80 is applied to the HTTP port on real server rs3. Slow-start list 101 for port 443 is applied to the SSL port on real server rs3. Note that slow-start list 101 for port 80 has no relation to slow-start list 101 for port 443.

In this configuration, port 80 on real server rs2 and ports 80 and 443 on real server rs3 are each subject to a user-configured slow-start mechanism. All other ports on the real servers are subject to the default slow-start mechanism described in “Default port slow-start mechanism” on page 287.

Globally disabling or re-enabling the slow-start mechanism

You can globally disable the mechanism. When you disable the slow-start mechanism, the ServerIron ADX can immediately send up to the maximum number of connections specified for the real server when the server becomes available. Disabling slow-start does not remove the slow-start configuration information from the real servers.

To re-activate slow-start, globally disable the feature.

ServerIronADX(config)#server no-slow-start



To globally re-enable slow-start, enter a command such as the following.

ServerIronADX(config)#no server no-slow-start

Syntax: [no] server no-slow-start

FIN close for server health checkFIN close replaces the RESET close for a TCP health check. To enable FIN close, use the following command.

ServerIronADX(config)#server keepalive-fin

Syntax: [no] server keepalive-fin

Health-check stateWhen you attach a health-check policy to a real server’s application port, the ServerIron ADX uses the health-check policy for periodic health checks and also for the next initial bringup of the server. When a health-check policy is attached, the ServerIron ADX no longer uses the default health check methods for initial bringup and periodic health checks.

For the ServerIron ADX to use a health-check policy, you must enable health checking (keepalive) at either the port profile level or the real server level for the server port. Otherwise, the state of the policy is FALSE, and the state of the server port remains in the state that it was before you attached the policy.

NOTEUse the show healthck command to display the policy state. Use the show server real-name name command to show the real server port state.

If health checking for a server port is disabled at the port profile level and at the real server level, the ServerIron ADX will continue to use whichever state is based on the health check during the initial server bringup. The ServerIron ADX will not be able to update the port’s state if the state changes.

To enable health checking at the port profile level, enter commands such as the following.

ServerIronADX(config)#server port 80ServerIronADX(config-port-80)#tcp keepalive enable

These commands enable health checking for TCP port 80.

For a UDP port, enter commands such as the following.

ServerIronADX(config)#server port 53ServerIronADX(config-port-53)#udp keepalive enable

To enable health checking at the real server level, enter commands such as the following.

ServerIronADX(config)#server real-name R1 10.10.10.10ServerIronADX(config-rs-R1)#port 80 keepalive

You can enable health checking at the port profile level, at the real server level, or both. Health checking must be enabled on at least one of these levels for the ServerIron ADX to use the health-check policy you attach to the port.



Enhanced server bringupEnhanced Server Bringup increases the speed of the bringup process by sending more (up to a maximum of 50) health-checks at one time.

In previous releases, the ServerIron ADX sent a health check for each real server port in a configuration, in the process of bringing up all of the ports. As a result, if the configuration contained many real server ports, the ServerIron ADX would take too much time to bring all of the ports up, one port at a time. To make the bringup process faster, the ServerIron ADX now sends more bringup health-checks at a time (up to a maximum of 50). The actual number of health-checks that the ServerIron ADX sends at any given instance depends on the number of server ports that are in the testing state. The ServerIron ADX performs Layer 2 and Layer 3 health checks, and if these are successful, it puts the port in a testing state. When it is time to send out bringup health checks, the ServerIron ADX collects all the server ports that are in the testing state, and sends them health checks.

The actual number of health checks that are sent out at any given instance also depends on the number of server ports for which the ServerIron ADX has sent out the health-check request and is still waiting for response. For example, if there are 75 server ports configured on the ServerIron ADX, and at the first instance 30 of these have passed the Layer 2 and Layer 3 checks, the ServerIron ADX sends out bringup health-checks to these 30 server ports. In the next 100 ms, when it is time to send out health-checks again, if only 20 of the above 30 server ports have responded and are UP, then there are 10 ports that are still in the bringup process. Assuming that the remaining 45 server ports have all passed Layer 2 and Layer 3 checks, the ServerIron ADX can send bringup health-checks for 40 server ports, because it is waiting for response for the 10 previously sent. In the next 100 ms cycle, it is time to send the next round of health-checks. At this point, if the ServerIron ADX got responses from all the 50 server ports, it now sends bringup health-checks for the remaining five server ports. The ServerIron ADX can send 50 bringup health-checks at a time separately for TCP and UDP ports.

Track-Port support under real server for health checksThe feature allows tracking of several secondary ports based on the health of the primary port. These secondary ports can be TCP or UDP ports.

Overview

When a group of ports are configured as part of a track-port, the ServerIron ADX can track the health of the master port (the port that is configured as the first port) and the rest of the ports in the track-port list will follow the state of the master port.

If the master port is down, the remaining ports in the track-port list would have their master state as down and traffic will not get forwarded to any of the ports on the track-port list, even though their individual health-checks state might be UP.



Configuration

To turn on this feature, use the hc-track-port command under the real server configuration as shown:

ServerIron ADX(config)#server real r1 10.1.1.1ServerIron ADX(config-real-server-r1) port 80ServerIron ADX(config-real-server-r1) port ftpServerIron ADX(config-real-server-r1) port dnsServerIron ADX(config-rsr1) hc-track-port 80 21 53

The ServerIron ADX now tracks the health status of port 80. If the health-check state of port 80 is DOWN, then all the other ports in the track-port list will have their health-check state as also DOWN. In this case, FTP and DNS have their master state as DOWN and traffic is not load balanced on these ports.

Syntax: [no] hc-track-port port ...port

The port variable specifies the secondary ports that will be tracked based on the health of the primary port. These secondary ports can be TCP or UDP ports.

Show Commands

The output from the show hc-track-port-state command displays when a primary port passed or failed a health check. Two examples are shown below:

In the first example above, the primary port passed the health check while in the second example, the primary port went down because of a failed health check.

NOTEThe output above may be truncated. For a complete output display, use the show hc-track-port-state detail command.

Syntax: show hc-track-port-state

ServerIronADX#show hc-track-port-stateReal Server track-port staters1 80 21 800 53 ACTIVE

ServerIronADX#show hc-track-port-stateReal Server track-port staters1 80 21 800 53 DOWN


Sample show commands 4

Sample show commands

Syslog for health status changeThe ServerIron ADX generates Syslog messages for changes to the Layer 4 or Layer 7 status of a real server. To display the Syslog buffer on the ServerIron ADX, enter the following command.

ServerIronADX(config)#show loggingDynamic Log Buffer (50 entries):03d02h47m38s:N:L4 server 192.168.1.170 danPC is down03d02h46m18s:N:L4 server 192.168.1.170 danPC is up03d02h46m08s:I:Interface ethernet5, state up

This example shows log entries for a real server named "danPC" with IP address 192.168.1.170. In this example, the real server passed a Layer 4 or Layer 7 health check ("up"), but then failed a Layer 4 or Layer 7 health check ("down") later.

Syntax: show logging

NOTEThe log messages do not distinguish between Layer 4 and Layer 7 health checks. When the status changes based on either type of health check, the ServerIron ADX logs the event as shown in this example.

Health checks for firewall paths

Changing the maximum number of Layer 3 path health-check retries

By default, the ServerIron ADX checks the health of each firewall and router path by sending an ICMP ping on the path every 400 milliseconds. If the ServerIron ADX receives one or more responses within 1.2 seconds, it concludes that the path is healthy. Otherwise, the ServerIron ADX reattempts the health check by sending another ping. By default, the ServerIron ADX reattempts an unanswered path health check up to three times before concluding that the path is unhealthy.

You can change the maximum number of retries to a value from 3 through 31 (ServerIron ADX Chassis devices) or 8 through 31 (all other ServerIron ADX models).

To change the maximum number of FWLB path health check attempts, enter a command such as the following at the firewall level of the CLI.

ServerIronADX(config-tc-2)#fw-health-check icmp 20

Syntax: [no] fw-health-check icmp num

The num variable specifies the maximum number of retries and can be a number from 3 through 31. The default is 3.


Sample show commands4

Enabling Layer 4 path health checks for FWLB

By default, the ServerIron ADX performs Layer 3 health checks of firewall paths, but not Layer 4 health checks. You can configure a ServerIron ADX in an FWLB configuration to use Layer 4 health checks instead of Layer 3 health checks for firewall paths. When you configure a Layer 4 health check, the Layer 3 (ICMP) health check, which is used by default, is disabled.

NOTEThe Layer 4 health check applies only to firewall paths. The ServerIron ADX always uses a Layer 3 (ICMP) health check to test the path to the router.

When you configure a Layer 4 health check for firewall paths, the ServerIron ADX sends Layer 4 health checks and also responds at Layer 4 to health checks from the ServerIron ADX at the other end of the firewall path.

To configure a Layer 4 health check, specify the protocol (TCP or UDP). Optionally, you also can specify the port:

• UDP – The ServerIron ADX sends and listens for path health check packets on the port you specify. If you do not specify a port, the ServerIron ADX uses port 7777 by default. The port number is used as both the source and destination UDP port number in the health check packets.

• TCP – The ServerIron ADX listens for path health check packets on the port you specify, but sends them using a randomly generated port number. If you do not specify a port, the ServerIron ADX uses port 999 as the destination port by default.

NOTEYou must configure the same Layer 4 health check parameters on all the ServerIrons in the FWLB configuration. Otherwise, the paths will fail the health checks.

To configure a Layer 4 health check for firewall paths, enter a command such as the following at the firewall group configuration level.

ServerIronADX(config-tc-2)#fw-health-check udp

The command in this example enables Layer 4 health checks on UDP port 7777. This ServerIron ADX sends firewall path health checks to UDP port 7777 and listens for health checks on UDP port 7777.

Syntax: [no] fw-health-check udp | tcp [TCP/UDP-portnum num]

The TCP/UDP-portnum num variable specifies the TCP or UDP port. It can be a number in one of the following ranges:

• For TCP, from 1 through 65535

• For UDP, from 1 through 1032 or 2033 through 65535

NOTEDo not use a number from 1033 through 2032 for UDP. Port numbers in this range are not supported for FWLB UDP health checks.

The num variable specifies the maximum number of retries. It can be a number from 1 – 31.

The default is 3.



Disabling Layer 4 health checks for FWLB

When you add an application port to a firewall definition, the ServerIron ADX automatically enables the Layer 4 health check for that port. You must disable the Layer 4 health check if the firewall is unable to act as a proxy for the application and respond to the health check. If the firewall does not respond to the health check, the ServerIron ADX assumes that the port is unavailable and stops sending traffic for the port to the firewall.

To disable the Layer 4 health check for an individual application on an individual firewall, enter a command such as the following at the firewall configuration level of the CLI.

ServerIronADX(config-rs-FW1)#port http no-health-check

Syntax: port [port-type | port-number] no-heath-check

The port-type variable specifies the port type that you want to disable from Layer 4 health check. It can any of the following values:

• dns – This option disables port 53 from health check.

• ftp – This option disables port 21 from health check. Ports 20 and 21 both are FTP ports but in the ServerIron ADX, the name “ftp” corresponds to port 21.

• http – This option disables port 80 from health check.

• imap4 – This option disables port 143 from health check.

• ldap – This option disables port 389 from health check.

• nntp – This option disables port 119 from health check.

• ntp – This option disables port 123 from health check.

• pop2 – This option disables port 109 from health check.

• pop3 – This option disables port 110 from health check.

• radius – This option disables UDP port 1812 from health check.

• radius-old – This option disables UDP port 1645 from health check. UDP port 1645, is used in some older RADIUS implementations instead of port 1812.

• smtp – This option disables port 25 from health check.

• snmp – This option disables port 161 from health check.

• ssl – This option disables port 443 from health check.

• telnet – This option disables port 23 from health check.

• tftp – This option disables port 69 from health check.

In addition, you can specify a port number in the port-number variable for ports other than those with name options.

Session table parametersThe ServerIron ADX maintains state information for TCP and UDP connections in the session table. The session table contains an entry for each TCP and UDP session between the ServerIron ADX and a client or real server. The ServerIron ADX uses the session table entries for health checks, stateful failover in hot-standby configurations, and other functions.

Each entry in the session table is a session. A session consists of the following:

• Source IP address

• Source application port



• Destination IP address

• Destination application port

• Protocol (TCP or UDP)

A connection consists of two sessions, a send session and a receive session. For example, a TCP connection between a client and a server consists of two sessions, a client-to-server session and a server-to-client session.

NOTE"Stateless" features such as stateless application ports and stateless health checks do not use session table entries.

This section describes how to configure the following session table parameters:

• Maximum number of sessions

• Maximum age of TCP session entries

• Maximum age of UDP session entries

• Clock scale for TCP and UDP session age timers

• Logging of session table entries

Configuring the maximum number of active sessions

An active session is a session entry in the ServerIron ADX session table. A UDP or TCP session that has become idle, but has not yet timed out (according to the UDP or TCP age timer), is an active session in this table.

To configure the maximum number of active sessions on a ServerIron ADX chassis, use the following command.

ServerIronADX(config)#server session-asm-limit 50000

Syntax: server session-asm-limit value

For this change to take effect, you must save the change to the startup-config file, then reload the software using the following commands.

ServerIronADX(config)#write memoryServerIronADX(config)#endServerIronADX#reload

Configuring fast session aging

ServerIron ADX supports fast session aging. When fast session aging is enabled with the server session-max-idle command, the ServerIron ADX can rapidly age out sessions when the number of available free sessions drops below specified threshold values.

The threshold values are specified as percentages of the maximum number of sessions available on the ServerIron ADX (the "max-sessions" value). The number of free sessions that trigger fast session aging is calculated using the following formula.

number of free sessions = (max-sessions * threshold) / 100

For example, if the max-sessions value on the ServerIron ADX is 500,000 sessions, and the threshold is 30%, then fast session aging is triggered when the number of free sessions reaches 150,000 or fewer; that is (500,000 * 30) / 100.



Two thresholds can be configured for fast session aging: the fast-age threshold and the random threshold:

• Fast-age threshold—When the number of free sessions drops below the fast-age threshold, sessions older than a specified time are aged out.

• Random threshold—When the number of free sessions drops below the random threshold, sessions are aged out randomly, without regard to session age. The random threshold can be equal to or lesser than the fast-age threshold.

For example, if the fast-age threshold is reached, sessions as old as or older than a specified amount of time (for example, 5 minutes) are aged out until the number of available sessions climbs above 150,000. If the random threshold is reached, sessions are aged out at random until the number of available sessions climbs above 150,000.

Fast session aging is disabled by default. To configure fast session aging, enter a command such as the following.

ServerIronADX(config)#server session-max-idle 5 30 10

Syntax: [no] session-max-idle max-idle-time [fast-age-threshold random-threshold]

The max-idle-time variable specifies the number of minutes allowed for idle sessions when a fast-age-threshold variable is configured. When the value specified in the fast-age-threshold variable is reached, sessions that are the same as and older than the threshold are aged out until the number of free sessions exceeds the value specified in the fast-age-threshold variable. The value of the max-idle-time variable can be from 1 through 30 minutes. The default is 0 minutes (disabled). To enable fast session aging, you must specify a value for the max-idle-time variable that is greater than 0.

When the number of available sessions drops below the value specified in the fast-age-threshold variable, sessions older than the value specified in the max-idle-time variable are aged out until the number of free sessions exceeds the threshold. The value of the fast-age-threshold variable is expressed as a percentage of the maximum number of sessions available on the ServerIron ADX. The value specified for the fast-age-threshold can be from 10 through 70 percent. The default is 33 percent.

When the number of available sessions drops below the value specified for the random-threshold variable, sessions are aged out randomly, without regard to session age, until the number of free sessions exceeds the threshold. The value specified for the random-threshold variable is expressed as a percentage of the maximum number of sessions available on the ServerIron ADX. The value specified for the random-threshold variable can be from 1 through 30 percent. The default is 0 percent (disabled).

NOTEEven though the max-idle-time value is not used with the random-age threshold, you must still specify a value for the max-idle-time variable when configuring the random threshold to enable the fast session aging feature.



Displaying information about fast aging

Two fields in the output of the show server sessions command display information about the sessions subject to fast aging.

The following is an example of the output from the show server sessions command. The fields related to fast session aging are highlighted in bold.

Syntax: show server sessions

If the fast-age threshold is configured, the command displays both the total number of sessions that were aged out because of the free sessions dropping below the fast-age threshold, and the number of sessions that were aged out in the last 60 seconds.

If the random threshold is configured, the command also displays the total number of sessions that were aged out at random because the number of free sessions dropped below the random threshold, along with the number of sessions that were aged out randomly in the last 60 seconds.

Clearing statistics counters for fast session aging

To clear the statistics counters for fast session aging, enter the following command.

ServerIronADX(config)#clear server fast-age-counters

Syntax: clear server fast-age-counters

This command resets the "Fast-aged : total" counter and corresponding "last 60 sec" counter as displayed by the show server sessions command.

Clearing statistics counters for sessions that aged out randomly

If the random threshold is configured, you can clear the statistics counters for sessions aged out randomly, by entering the following command.

ServerIronADX(config)#clear server random-age-counters

Syntax: clear server random-age-counters

This command resets the "Random-aged : total" counter and corresponding "last 60 sec" counter as displayed by the show server sessions command.

ServerIronADX#show server sessions

Avail. Sessions = 524282 Total Sessions = 524288Total C->S Conn = 0 Total S->C Conn = 0Total Reassign = 0 Unsuccessful Conn = 0Fast-aged : total = 0 last 60 sec = 0Random-aged : total = 0 last 60 sec = 0Server State - 1:enabled, 2:failed, 3:test, 4:suspect, 5:grace_dn, 6:active

Real Server State CurrConn TotConn TotRevConn CurrSess PeakConn

rs1 1 0 0 0 0 0rs2 1 0 0 0 0 0



Configuring TCP ageThe TCP age specifies how many minutes a TCP server connection can remain inactive before the ServerIron ADX times out the session.

If you change the TCP age, the change affects only new TCP sessions that start after you make the change. The maximum age for sessions that are already in the session table does not change.

NOTEThis parameter globally sets the age for all TCP ports. To override the setting for an individual TCP port, change that port’s profile. Refer to “Overriding the global TCP or UDP age” on page 248.

To modify the server TCP age, enter a command such as the following.

ServerIronADX(config)#server tcp-age 20

Syntax: server tcp-age time

The time variable is a value from 2 through 60 minutes. The default is 30 minutes.

Configuring UDP ageYou can modify the aging out parameter for inactive UDP server connections. To modify the server UDP age to 20 minutes from the default value of 5 minutes, enter a command such as the following.

ServerIronADX(config)#server udp-age 20

This parameter globally sets the age for all UDP ports. To override the setting for an individual TCP port, change that port’s profile. Refer to “Overriding the global TCP or UDP age” on page 248.

Syntax: [no] server udp-age minutes

The minutes variable is a value from 2 through 60 minutes. The default is 5 minutes; the default age for DNS and RADIUS is 2 minutes.

The ServerIron ADX immediately deletes a UDP DNS or RADIUS session table entry when it receives a reply for the application from a real server. You can configure the ServerIron ADX to age these ports like other UDP ports, using the UDP age timer. Refer to “Enabling normal UDP aging for DNS and RADIUS” on page 160.

For DNS and RADIUS UDP load balancing, the age value does not follow the normal configuration and default value unless the udp-normal-age option is configured on the port, under the virtual server port definition, the port dns udp-normal-age command. (Refer to “Enabling normal UDP aging for DNS and RADIUS” on page 160.) The default UDP age will always be 2 minutes unless the udp-normal-age option is configured.

Setting the clock scaleThe ServerIron ADX uses a configurable clock scale for the following session timers:

• TCP age

• UDP age

To adjust the clock scale for configurations that require TCP or UDP timeouts longer than the maximum configurable value (60 minutes), enter a command such as the following.

ServerIronADX(config)#server clock-scale 2



When you set the clock scale to 2, the TCP and UDP age timer values are multiplied by 2. As a result, a TCP age of 60 would then be equivalent to 120 minutes instead of 60 minutes.

Syntax: [no] server clock-scale multiplier

The multiplier variable can be a value from 1 through 20. The default is 1.

Syslog for session table entriesYou can configure the ServerIron ADX to send a message to external Syslog servers when the software creates a session table entry. The messages indicate the following information:

• Source IP address

• Source TCP or UDP application port

• Destination IP address

• Destination TCP or UDP application port

• Layer 4 protocol (TCP or UDP)

• Message time (measured in units of 100 milliseconds, relative to system uptime)

• URL (optional)

• Cookie (optional)

• Internet (applies to TCS only)

You can enable TCP/UDP logging on a global basis for all TCP and UDP ports or for individual TCP or UDP ports.

When you enable TCP/UDP logging, you can specify whether all new session table entries generate log messages or only the entries that are used for Source NAT.

In addition, you can enable logging for URL or Cookie information. The URL logging option applies only when URL switching is enabled. The Cookie logging option applies only when Cookie switching is enabled.

Here is an example of a Syslog message for a session.

src-ip = 192.168.002.032 src-port = 00197 dst-ip = 192.168.002.012 dst-port = 00080 protocol = TCP time =0000078656 Url = abcdefghijklmnopCookie = qrstuvwxyz Internet

The "Internet" parameter at the end of the message applies only to TCS, and indicates that the ServerIron ADX sent the client request to the Internet instead of to a cache server.

The time value in this example is in the format for devices on which the system time add date have not been set.

NOTEThe feature description and command syntax use the terms “session” and “connection”. A connection consists of multiple sessions, for the send and receive directions.

NOTEBecause the log messages are generated when the software creates a session table entry, features that do not use session table entries do not result in log messages. For example, if you configure a TCP or UDP port to be stateless, the ServerIron ADX does not create session table entries for the port and therefore does not generate log messages for the port.



Enabling TCP/UDP session logging

When TCP/UDP session logging is enabled, the ServerIron ADX sends a message to the external Syslog servers when the software creates a session table entry. You can enable session logging globally for all ports or on an individual basis for TCP or UDP ports.

To globally enable logging for all new session table entries, enter the following command.

ServerIronADX(config)#server connection-log all

To enable logging only for new sessions that are used for Source NAT, enter the following command.

ServerIronADX(config)#server connection-log src-nat

To enable session logging for a specific TCP or UDP port, enter the following command.

ServerIronADX(config)#server port 80ServerIronADX(config-port-80)#connection-log all url cookie

Syntax: [no] server connection-log all | src-nat [url] [cookie]

NOTEThe all option enables logging for all sessions.

NOTEThe src-nat option enables logging only for sessions that are used for Source NAT.

NOTEThe url option enables logging of URL information for sessions that contain a URL. This option applies only when URL switching is enabled.

NOTEThe cookie option enables logging of cookie information for sessions that contain a cookie.This option applies only when cookie switching is enabled.



Chapter

5
Layer 7 Content Switching
Layer 7 content switching overviewLayer 7 switching allows the ServerIron ADX to make forwarding decisions about HTTP traffic based on information in a URL, cookie, or SSL session ID. Advanced Layer 7 content switching allows the ServerIron to make forwarding decisions about HTTP traffic by analyzing information contained within the traffic. CSW also enables Layer 7 application content based traffic direction for non-HTTP protocols such as Financial Information Exchange (FIX) protocol.

The advanced Layer 7 content switching provides an enhancement over the Layer 7 switching feature available in previous ServerIron ADX releases by allowing you to configure load balancing based on multiple HTTP header fields and XML content. The Layer 7 switching feature available in previous releases is limited to load balancing traffic based on hostname, URL, and cookie fields in the HTTP header.

Specifically, the new Layer 7 content switching feature provides the following functionality:

• Load balancing based on any specified HTTP header

• Load balancing based on XML content

• Ability to make complex load-balancing decisions based on multiple HTTP headers or XML tags

• Support for redirecting requests to alternate URLs or domains

• Support for persisting requests to servers, along with simple forwarding actions.

• Support for content-rewrite functions, including cookie and HTTP header insertion and deletion.

NOTEYou cannot use FWLB and the features described in this chapter on the same ServerIron ADX.

NOTEFast session synch is not supported in Layer 7 or TCP-offload configurations.

NOTEYou can define up to 255 policies and 1000 rules system wide. A maximum of 500 rules can be defined under a single policy.

NOTELayer 7 content switching load balancing is not supported where both sticky connections and track group features are configured.

NOTEYou cannot enable URL switching and Layer 7 content switching simultaneously on the same virtual server.

305

Configuring Layer 7 content switching5

NOTEAlias ports should be treated like regular ports and should have the same server ID and group ID

NOTEIf content switching is enabled on the ServerIron ADX, and source-NAT is enabled globally, then the 446 (IPv4 client --> IPv4 VIP --> IPv6 real server) traffic mode is also source natted.

NOTEIf content switching (csw) is enabled and if source-NAT is globally configured, then 446 Layer 7 HTTP traffic is also source natted. If csw is not enabled and the source-NAT is globally configured, then the IPv6 prefix for 446 traffic will take precedence.

Configuring Layer 7 content switchingTo configure Layer 7 content switching, you define content switching rules and policies. A rule specifies the content that the ServerIron ADX looks for in the incoming traffic, and a policy associates rules with one or more actions that specify how the ServerIron ADX handles traffic matching the rule.

The following sections explain how to configure Layer 7 content switching on a ServerIron ADX Chassis device and how to display information about a Layer 7 content switching configuration.

Enabling CSWTo enable Layer 7 content switching, you bind a content switching policy to a virtual server. For example, to enable Layer 7 content switching on a virtual server called cswVIP, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip cswVIP 192.168.20.254ServerIronADX(config-vs-cswVIP)#port http csw-policy p1ServerIronADX(config-vs-cswVIP)#port http csw

Syntax: [no] port portnum csw-policy policy-name

Syntax: [no] port portnum csw

The policy-name variable is a Layer 7 content switching policy. Refer to “Creating a policy” on page 313.

Specifying scan depth To configure actions based on content carried on top of the HTTP protocol (for example, XML content) you must specify how far into the packet the ServerIron ADX scans for the content. The ServerIron ADX scans up to the specified limit. If you do not specify a scan depth, then the ServerIron ADX scans to the end of the packet.

To specify the scan depth for HTTP content, enter commands such as the following:

ServerIronADX(config)#server virtual-name-or-ip cswVIP 192.168.20.254ServerIronADX(config-vs-cswVIP)#port http csw-scan-depth 128ServerIronADX(config-vs-cswVIP)#port http csw

Syntax: [no] port portnum csw-scan-depth length


Configuring Layer 7 content switching 5

The length variable specifies the number of bytes the ServerIron ADX scans for content in a packet. You can specify up to 8192 bytes. By default, the ServerIron ADX scans to the end of the packet.

Enabling CSW load balanceIn HTTP 1.1, a client can send multiple requests over the same connection. The current behavior is that ServerIron ADX regards all requests as independent requests, namely it uses the load balance predictor to perform server selection for each request. This is true even where the next request from the client's connection goes to the same server group. After server selection, this request may go to a different real server within the same server group. This can introduce the extra delay for the client because it needs to establish a new connection for the new real server. In version 12.4.00, if the next request from the same client connection is forwarded within the same server group, the ServerIron ADX will not run the server load balance predictor algorithm to choose a new server. It will just use the same real server for the current request. If the next request goes to a different server group, the ServerIron ADX will follow the current code behavior to perform server section.

The following command sets the behavior back to pre-12.4.00 behavior which enables use of a load balancing predictor.

ServerIronADX(config)#server csw request-load-balance

Syntax: [no] server csw request-load-balance

Use the no form of this command if you have previously enabled the command and want to remove it.

Put simply, if the client sends two requests to the ServerIron ADX in the same connection and these two requests are switched to the same group, with server csw request-load-balance command configured, CSW will do server selection based on load balance predictor; without this command configured, CSW will still use the same server used by the first client request for the second one.

NOTEThe server csw request-load-balance command is only applicable to keep-alive and TCP-offload mode.

CSW rulesThis section describes the rules available for Layer 7 content switching. You can define the following types of rules:

• HTTP method rules – Cause the ServerIron ADX to make a load balancing decision based on the HTTP method in an incoming packet. Refer to “Configuring an HTTP method rule” on page 308.

• HTTP version rules – Cause the ServerIron ADX to make a load balancing decision based on the HTTP version of an incoming packet. Refer to “Configuring an HTTP version rule” on page 309.

• URL rules – Cause the ServerIron ADX to make a load balancing decision based on the contents of the URL string in an incoming packet. Refer to “URL rules” on page 309.

• HTTP header rules – Cause the ServerIron ADX to make a load balancing decision based on the contents of an HTTP header field in an incoming packet. Refer to “HTTP header rules” on page 310.



• XML tag rules – Cause the ServerIron ADX to make a load balancing decision based on the contents of an XML tag in an incoming packet. Refer to “XML tag rules” on page 311.

In addition, you can combine rules with logical operators AND, OR, and NOT to create nested rules. Refer to “Define a nested rule (optional)” on page 363.

NOTEFor CSW rules that use the prefix or suffix method, the matching string will be the complete string and the offset is starts from the matching string.

Configuring an HTTP method rule

To set up an HTTP method rule that causes the ServerIron ADX to make a load balancing decision based on the HTTP method in an incoming packet, enter a command such as the following.

ServerIronADX(config)#csw-rule r1 method eq PUT

This example creates a rule called r1 that matches if an incoming packet contains the PUT method.

Syntax: [no] csw-rule rule-name method eq method-string

The rule-name value can be up to 80 characters in length.

The method-string variable can be GET, HEAD, POST, OPTIONS, PUT, DELETE, TRACE, PROPFIND, MOVE, CONNECT, BDELETE, PROPPATCH, COPY, LOCK, UNLOCK, MKCOL, BCOPY, BMOVE, POLL, SUBSCRIBE, SEARCH, BPROPPATCH, RPC_OUT_DATA, or RPC_IN_DATA.



Configuring an HTTP version rule

To set up an HTTP method rule that causes the ServerIron ADX to make a load balancing decision based on the HTTP version of an incoming packet, enter a command such as the following.

ServerIronADX(config)#csw-rule r1 version eq 1.1

This example creates a rule called r1 that matches if an incoming packet uses HTTP version 1.1.

Syntax: [no] csw-rule rule-name version eq http-version

The rule-name value can be up to 80 characters in length.

The http-version variable can be 0.9, 1.0, or 1.1.

URL rules

URL rules cause the ServerIron ADX to make a load-balancing decision based on the contents of the URL string in an incoming packet.

Table 23 lists the URL rules available for Layer 7 content switching.

TABLE 23 URL rules for Layer 7 content switching

URL rule name

Description Syntax Example

URL Exists Matches if a URL string exists in the incoming packet.

[no] csw-rule rule-name url exists

csw-rule r1 url exists

URL Prefix Matches if the URL string begins with the specified prefix.

[no] csw-rule rule-name url prefix value

csw-rule r1 url prefix "/home"

URL Suffix Matches if the URL string ends with the specified suffix.

[no] csw-rule rule-name url suffix value

csw-rule r1 url suffix ".gif"

URL Pattern Matches if the specified pattern exists anywhere within the URL string.

[no] csw-rule rule-name url pattern value

csw-rule r1 url pattern "test"

URL Equals Matches if the URL string is equal to the specified value.

[no] csw-rule rule-name url equals value

csw-rule r1 url equals "/home.html"

URL Search Matches if the URL string contains any one of up to five specified values. This type of rule can be used with the persist action.

[no] csw-rule rule-name url search value

csw-rule r1 url search "srvr1"csw-rule r1 url search "srvr2"csw-rule r1 url search "srvr3"csw-rule r1 url search "srvr4"csw-rule r1 url search "srvr5"



HTTP header rules

HTTP header rules cause the ServerIron ADX to make a load-balancing decision based on the contents of an HTTP header field in an incoming packet.

In an Layer 7 content switching configuration, you can configure rules for the following HTTP header fields: Connection, Transfer-Encoding, Content-Length, Host, Cookie, Pragma, and Cache-Control, as well as up to 10 other HTTP header fields.

Table 24 lists the HTTP header rules available for Layer 7 content switching.

TABLE 24 HTTP header rules for Layer 7 content switching

HTTP header rule name


Header Exists Matches if the specified HTTP header field exists in the incoming packet.

[no] csw-rule rule-name header header-name exists

csw-rule r1 header "host" exists

Header Prefix Matches if the value in the specified HTTP header field begins with the specified prefix.

[no] csw-rule rule-name header header-name prefix value

csw-rule r1 header "host" prefix "www"

Header Suffix Matches if the value in the specified HTTP header field ends with the specified suffix.

[no] csw-rule rule-name header header-name suffix value

csw-rule r1 header "host" suffix "com"

Header Pattern

Matches if the specified pattern exists anywhere within the specified HTTP header field.

[no] csw-rule rule-name header header-name pattern value

csw-rule r1 header "cookie" pattern "Serverid"

Header Equals

Matches if the contents of the specified HTTP header field are equal to the specified value.

[no] csw-rule rule-name header header-name equals value

csw-rule r1 header "host" equals "www.example4.com"

Header Search

Matches if the specified HTTP header field contains any one of up to five specified values. This type of rule can be used with the persist action.

[no] csw-rule rule-name header header-name search value

csw-rule r1 header "cookie" search "ServerId1"csw-rule r1 header "cookie" search "ServerId2"



XML tag rules

XML tag rules cause the ServerIron ADX to make a load balancing decision based on the contents of an XML tag in an incoming packet. Rules for up to 200 different XML tags can be specified in an Layer 7 content switching configuration. In a given policy, you can include rules for up to 5 XML tags.

Table 25 lists the XML tag rules for Layer 7 content switching.

TABLE 25 XML tag rules for Layer 7 content switching

XML tag rule name


XML Tag Exists

Matches if the specified XML tag exists in the incoming packet.

[no] csw-rule rule-name xml-tag tag-name exists

csw-rule r1 xml-tag "name" exists

XML Tag Prefix

Matches if the value in the specified XML tag begins with the specified prefix.

[no] csw-rule rule-name xml-tag tag-name prefix value

csw-rule r1 xml-tag "name" prefix "ge"

XML Tag Suffix

Matches if the value in the specified XML tag ends with the specified suffix.

[no] csw-rule rule-name xml-tag tag-name suffix value

csw-rule r1 xml-tag "name" suffix "ge"

XML Tag Pattern

Matches if the specified pattern exists anywhere within the specified XML tag.

[no] csw-rule rule-name xml-tag tag-name pattern value

csw-rule r1 xml-tag "name" pattern "org"

XML Tag Equals

Matches if the contents of the specified XML tag are equal to the specified value.

[no] csw-rule rule-name xml-tag tag-name equals value

csw-rule r1 xml-tag "name" equals "george"

XML Tag Search

Matches if the specified XML tag contains any one of up to five specified values. This type of rule can be used with the persist action.

[no] csw-rule rule-name xml-tag tag-name search value

csw-rule r1 xml-tag "name" search "geo" csw-rule r1 xml-tag "name" search "edw"



Case-insensitive match for content switching

With Case-Insensitive Match for content switching (CSW you can optionally specify a CSW-rule or CSW-policy to be case insensitive and the consequent match ignores case for the input.

The following example shows how to configure a case-insensitive rule.

ServerIronADX(config)#csw-rule r1 url pattern /test/index.html case-insensitive

Syntax: csw-rule rule-name url | header | method | xml-tag pattern pattern-to-match case-insensitive

The optional case-insensitive keyword specifies the pattern match to be case insensitive.

The following example shows how to configure a case-insensitive policy.

ServerIronADX(config)#csw-policy p1 case-insensitive

Syntax: csw-policy policy-name case-insensitive

The optional case-insensitive keyword specifies that this policy is case-insensitive.

NOTEYou cannot mix case-insensitive policy and case sensitive-rules, or vice versa.

Wildcards in CSW rules for URL prefixes

Wildcards in CSW rules for URL prefixes behave as described for the following CSW rule:

csw-rule "pages0" url prefix "/pages/0*"

In this case, "/pages/0*" does not match on " /pages/0". It would only match on URLs such as "/pages/01" and "/pages/011119011", where the URL is at least one byte longer that the part of the rule before the asterisk.

CSW policiesA policy specifies the action to take when a rule is matched. You can specify the following actions in a policy:

• Forward action – Causes the ServerIron ADX to forward packets matching a specified rule to a specified real server or server group. Refer to “Configuring the forward action” on page 313.

• Reply-error action – Causes the ServerIron ADX to send a 403 error code page back to the client when the specified rule is matched. Refer to “Configuring the reply-error action” on page 316.

• Log action – Causes the ServerIron ADX to write a message to Syslog when the specified rule is matched. You can optionally customize the format of the Syslog message. Refer to “Configuring the log action” on page 316.

• Redirect action – Causes the ServerIron ADX to redirect a request to an alternate domain, URL, or port when the specified rule is matched. Refer to “Configuring redirect” on page 328.

• Persist action – causes the ServerIron ADX to send requests with similar content to the same server when the specified rule is matched. Refer to “Configuring the persist action” on page 314.



NOTEIf no rule is matched, traffic is directed to the internet.

NOTEAlias ports should be treated like regular ports and should have the same server ID and group ID.

Creating a policy

To create a policy for Layer 7 content switching, enter a command such as the following.

ServerIronADX(config)#csw-policy policy1

Syntax: [no] csw-policy policy-name

The policy-name variable can be up to 80 characters in length.

Configuring the forward action

The forward action causes the ServerIron ADX to forward packets matching a specified rule to a specified real server or server group.

For example, the following command specifies that packets matching rule r1 be forwarded to real server 1029.

ServerIronADX(config-csw-policy1)#match r1 forward 1029

Syntax: [no] match rule-name forward id [cookie-name name]

The rule-name variable is the name of a previously configured Layer 7 content switching rule.

The id variable refers to a real server or server group ID. An ID between 0 and 1023 indicates a server group ID, and an is between 1024 and 2047 indicates a real server ID.

NOTEThe real server ID range is limited to 1024-1+the maximum number of real servers that can be configured on the ServerIron ADX model. For example, if the maximum server limit is 16384, then the valid real server ID range is from 1024 to 1024-1+16384=17407.

If you specify a server group ID, you can optionally specify a cookie name. When you specify a cookie name, the ServerIron ADX performs cookie switching on packets matching the rule, which ensures that packets matching the rule go to the same real server within the server group. Refer to "Configuring Cookie Switching" in the ServerIron ADX for more information.



Configuring the persist action

The persist action causes the ServerIron ADX to send requests with similar content to the same server when the specified rule is matched. When a rule is matched, the ServerIron ADX uses the content that matched the rule, in combination with a specified persistence method, to select a server or server group to which to send the packet.

When a rule is associated with the persist action, a server or server group is selected as follows.

1. An incoming packet matches a configured CSW rule. For example, a CSW rule matches if an incoming packet contains a cookie header field with the string “ServerID” as shown in the following.

ServerIronADX(config)#csw-rule r1 header "cookie" search "ServerId"

The persist action can then be used in conjunction with the above CSW rule.

2. The ServerIron ADX examines the matched content to determine the persist string. The persist string contains the portion after the matched string that the ServerIron ADX uses, (along with the persist method) to select a real server (or server group) to which to send the packet.

For example, in CSW rule r1 defined above, the matched content could be something like: “ServerID=2”

Then, you can specify that the persist string be a segment of the matched content, starting from a specified offset from the matched string (ServerID) and lasting for a specified length. In the example above, if you specify an offset of “1” and a length of “1”, the persist string would be “2”.

3. The ServerIron ADX uses the persist string along with the configured persist method to select a real server or group. By default, the ServerIron ADX uses a hash-to-bucket persist method to select a real server.

The hash-to--bucket persist method is illustrated in the following figure.

FIGURE 31 Hash-to-bucket persist method



For a given rule, you can configure a primary persist action and a secondary persist action. If the primary persist action does not return a valid persist string, or if the server indicated by the primary persist string is not available, the ServerIron ADX uses the secondary persist action to direct packets to a server.

The following commands configure a CSW rule and policy that use the persist action.

ServerIronADX(config)#csw-rule r1 header host existsServerIronADX(config)#csw-policy p1ServerIronADX(config-csw-p1)#match r1 persist offset 0 length 0

In the above example, the csw-rule command creates a rule that matches if an incoming packet contains an HTTP host header field. The csw-policy command creates a policy called p1. The match r1 persist command associates the rule with the persist action. As a result, if an incoming packet has an HTTP host header field, the contents of the host header field are used as the persist string. The ServerIron ADX uses the persist string along with the default hashing-bucket persist method to calculate the real server to which to send the packet.

Syntax: [no] match rule-name persist offset offset length length [[persist-method] [secondary]]

or

Syntax: [no] match rule-name persist offset offset terminator string [[persist-method] [secondary]]

The offset variable specifies the offset in bytes from the end of the matched string, matched by the rule-name to be used as the persist string. If you specify 0 as the offset, the persist string begins right after the matched string.

The length variable specifies the length in bytes of the persist string. If you specify 0 as the length, the persist string ends at the end of the matched content.

The terminator string variable specifies the substring with which the persist string ends.

The persist-method variable specifies which of the following persist methods you want to use.

• hash-to-bucket – Hashes the persist string to a hashing bucket, as illustrated in Figure 31. This is the default.

• hash-to-group-id – Hashes the persist string to a server group ID, instead of to a hashing bucket.

• group-or-server-id – Translates the persist string to the ID of a real server or server group.

• server-name – Translates the persist string to the name of a real server.

• alias-name – Translates the persist string to the name of an alias.

The secondary keyword indicates that this is a secondary persist action for the rule. If the primary persist action does not return a valid persist string, or if the server indicated by the primary persist string is not available, the ServerIron ADX uses the secondary persist action to direct packets to a server.

NOTEBy configuring both a CSW policy that utilizes the persist action and a TCP or UDP port as sticky, you can implicitly enable persistence fallback. In this scenario, the CSW policy defines the default method of defining persistence. However, If no cookie is detected, the ServerIron ADX falls back to the sticky persistence configured for the address.



Configuring the reply-error action

The reply-error action causes the ServerIron ADX to send a 403 error code page back to the client when the specified rule is matched.

For example, to cause the ServerIron ADX to send a 403 error code page to a client that sent a packet that matched rule r1, enter the following command.

ServerIronADX(config-csw-policy1)#match r1 reply-error

Syntax: [no] match rule-name reply-error

Configuring the log action

The CSW match log action only logs to a log server, not the local log of the SI (show logging). You must configure a remote server (per the global logging ip-addr command) to receive the log. The syslog server cannot be connected to the management port because CSW log action is processed by the BP, and the management port is controlled by the MP.

NOTEThe log action requires a primary action forward or persist to be configured.

An example Syslog message follows.

192.168.9.210 80 HTTP Rule matched, Forward

To cause the ServerIron ADX to write a message to Syslog when rule r1 is matched, enter a command such as the following:

ServerIronADX(config-csw-policy1)#match r1 log

Syntax: [no] match rule-name log [format]

By default, the format of the Syslog message is as follows.

source-ipaddr source-port protocol Rule matched, action-message

Additionally, you can change the format of the Syslog message using the following tokens:

• $SIP – Source IP address

• $DIP – Destination IP address

• $SPT – Source port

• $DPT – Destination port

• $HST – Host name

• $URL – URL

• $RUL – Rule name

• $ACT – Action

• $CNT – Matched content, such as the matched method, URL, version, or HTTP header. THis option is only supported when using TCP/UDP Content Switching.

For example, the following command specifies an alternate format for the Syslog message:

ServerIronADX(config-csw-policy1)#match r1 log "$SIP:$SPT->$DIP:$DPT,ru $RUL hit $ACT"



In this example, when a packet matches rule r1, a message such as the following is written to Syslog.

192.168.9.210:80->10.10.10.10:80, ru r1 hit forward

Inserting a cookie

You can configure the ServerIron ADX to insert a cookie into an HTTP response when a specified rule is matched. When the rule is matched, a cookie is inserted in the response when any of the following occur:

• No cookie header is found in the HTTP request, or a cookie header exists but it does not contain the cookie name specified by the rewrite cookie-insert command.

• The specified cookie name is found in the HTTP request, but the cookie value is out of the range used for cookie switching. The cookie value must be between 1 and 17407.

• The specified cookie name is found in the HTTP request, but the real server or server group indicated by the cookie value is not available.

For example, the following command causes the ServerIron ADX to insert the cookie indicated by the rewrite cookie-insert command into the HTTP response when rule r1 is matched.

ServerIronADX(config-csw-policy1)#match r1 rewrite insert-cookie

Syntax: [no] match rule-name rewrite insert-cookie

Deleting a cookie

Cookie deletion causes the ServerIron ADX to delete the cookies that it set. The ServerIron removes the cookie from the HTTP request prior to sending the request to the server.

For example, the following command causes the ServerIron ADX to delete the cookie indicated by the rewrite cookie-insert command from the HTTP response when rule r1 is matched.

ServerIronADX(config-csw-policy1)#match r1 rewrite delete-cookie

Syntax: [no] match rule-name rewrite delete-cookie

Damaging a cookie

Cookie damage consists of altering the cookie header so that it does not contain any cookie that matches the name of the cookie inserted by the ServerIron ADX.

For example, the following command causes the ServerIron ADX to damage the cookie indicated by the rewrite cookie-insert command in the HTTP response when rule r1 is matched.

ServerIronADX(config-csw-policy1)#match r1 rewrite destroy-cookie

Syntax: [no] match rule-name rewrite destroy-cookie

Inserting an HTTP header

HTTP header insertion causes the ServerIron ADX to insert a header into the HTTP requests that it receives on a virtual server or into the HTTP responses that it sends out from a virtual server. The header is specified within the CSW match command using the request-insert parameter (for HTTP requests) or the response-insert parameter (for HTTP responses).



To cause the ServerIron ADX to insert a standard HTTP “Via:” header into HTTP requests matching rule r1, enter the following command.

ServerIronADX(config-csw-p1)#match r1 rewrite request-insert header "Via: ServerIron ADX"

Syntax: [no] match rule-name rewrite request-insert header header

The header variable specifies the string that will be inserted.

To cause the ServerIron ADX to insert the header "SI-ADX: proto=HTTP+MMS" into the HTTP responses (matching rule r1) that it sends from the virtual server, enter the following command.

ServerIronADX(config-csw-policy1)#match r1 rewrite response-insert header "SI-ADX: proto=HTTP+MMS"

Syntax: [no] match rule-name rewrite response-insert header header

The header variable specifies the string that will be inserted.

Inserting an IP address in a header

HTTP Header insertion can direct the ServerIron ADX to insert the Client IP address into the HTTP requests it receives on a virtual server that matches a CSW rule you define.

This feature can be useful in situations where Source Network Address Translation (source NAT) is enabled on a ServerIron ADX. With Source NAT enabled, original source IP addresses are translated into one common IP address. As a result, servers are unable to identify clients by their original source IP addresses. In some cases, the real source IP addresses of the clients may be necessary; for example, for server applications to report statistics, or for web administrators who may need to know the real source IP addresses of the clients in order to secure the system.

You can use the HTTP header insertion feature to insert the original source IP address into the HTTP request. Servers are then able to identify clients by their original source IP addresses.

To cause the ServerIron ADX to insert the IP address of the connecting client into HTTP requests matching rule r1, enter the following command.

ServerIronADX(config-csw-policy1)#match r1 rewrite request-insert client-ip "MyClientIP"

Syntax: [no] match rule-name rewrite request-insert client-ip header

Inserting a client certificate into an HTTP request

HTTP Header insertion can direct the ServerIron ADX to insert a client certificate that you specify into the HTTP requests it receives on a virtual server that matches a CSW rule you define.

The following configuration of CSW policy "p1" directs the ServerIron ADX to insert the entire certificate chain in HTTP requests it receives on a virtual server that match the "r1" CSW rule and to set the prefix header to "SSL".

ServerIronADX(config)#csw-policy p1ServerIronADX(config-csw-p1)#match r1 rewrite request-insert client-cert entire-chain ServerIronADX(config-csw-p1)#match r1 rewrite request-insert client-cert certheader-prefix "SSL"

Syntax: [no] match rule-name rewrite request-insert client-cert entire-chain | leaf-cert | wellknown-fields | certheader-prefix prefix-header



The entire-chain parameter directs the switch to insert the entire certificate chain. It is in PEM format and BASE64 encoded. The header name is Client-cert. Refer to Table 33 for details.

The leaf-cert parameter directs the switch to insert only the leaf certificate in the certificate chain. It is in PEM format and BASE64 encoded. The header name is Client-cert. Refer to Table 33 for details.

The wellknown-fields parameter directs the switch to insert only the well-known fields described in Table 27. These fields are in ASCII format.

The certheader-prefix parameter directs the switch to set the header prefix of the header listed in Table 26 or Table 27 to the value specified by the prefix-header variable. For example, if you define the prefix-header variable to the well known prefix "SSL", the "Client-Cert" header becomes "SSL-Client-Cert".

The following example configures the CSW policy "p1" to insert the entire certificate chain in HTTP requests it receives on a virtual server and to insert the "SSL" as the certificate header prefix.

ServerIronADX(config)#csw-policy p1 ServerIronADX(config-csw-p1)#match r1 rewrite request-insert header entire-chainServerIronADX(config-csw-p1)#match r1 rewrite request-insert header cert-header-prefix "SSL"

Configuring Rewrite request-delete

HTTP URL Rewrite allows the ServerIron ADX to delete a string or portion of a string from inside the incoming client request. The following options are described:

• “Deleting a matched-string” on page 320

• “Deleting content at positive offset” on page 321

TABLE 26 Header inserted when entire-chain or leaf-cert is configured

This field Displays

Client-Cert The entire client certificate chain or the leaf certificate.

TABLE 27 Header inserted when well-known fields are configured

Field Displays

Client-Cert-Version Version of the client certificate.

Client-Cert-Serial Serial number of the client certificate.

Client-Cert-Start Date certificate not valid before.

Client-Cert-End Date certificate not valid after.

Client-Cert-Subject Subject’s distinguished name.

Client-Cert-Subject-CN Subject’s common name.

Client-Cert-Subject-Alt-CN Subject’s alternate name.

Client-Cert-Issuer Issuer’s distinguished name.

Client-Cert-Issuer-CN Issuer’s common name.

Client-Cert-Data-Signature-Algorithm Hashing and encryption method.

Client-Cert-Signature-Algorithm Certificate signature algorithm.



• “Deleting content at negative offset” on page 322

• “Deleting a string” on page 323

Deleting a matched-string To configure a request to delete a matched string in a CSW rule, follow these steps.

1. Define a CSW rule to search for a sub-string in a URL.

ServerIronADX(config)#csw-rule r11 url pattern "-sample"

Syntax: csw-rule rule-name url pattern url-content

2. Define a CSW policy.

ServerIronADX(config)#csw-policy mypolicy

Syntax: csw-policy policy-name

3. Specify a primary action to forward a request to a server with an ID of 1025 when rule r11 is matched.

ServerIronADX(config-csw-mypolicy)#match r11 forward 1025

Syntax: match rule-name forward server-id

4. Specify a dependent action to delete the sub-string -sample when it is found in the URL.

ServerIronADX(config-csw-mypolicy)#match r11 rewrite request-delete matched-string

Syntax: match rule-name rewrite request-delete matched-string

5. Specify a dependent log action.

ServerIronADX(config-csw-mypolicy)#match r11 log

Syntax: match rule-name log

6. Specify a default action.

ServerIronADX(config-csw-mypolicy)#default forward 1026

Syntax: default forward server-id

NOTEThe following section assumes you have already completed the previous configuration.

If the ServerIronADX were to receive a request for URL /abc/xyz-sample/index.html, it would take the following actions:

• Delete sub-string "-sample" in the URL, which becomes /abc/xyz/index.html.

• Forward the request to Web Server 1.

• Log primary Forward action to the log server.

In this case, "-sample" is the deleted string that CSW rule r11 matches. The request is forwarded to the server with server ID 1025, which is defined by primary CSW action match r11 forward 1025. The URLs in the following two HTTP request messages show the difference between the original request and the rewritten request.



If there is no sub-string "-sample" in the URL of the HTTP request, rule r11 is not hit, the request is sent to the server with server ID of 1026, which is defined by the default rule default forward 1026.

Example Original HTTP request:

GET /abc/xyz-sample/index.html HTTP/1.1\r\nHost: www.example5.com\r\nUser-Agent: Mozilla/5.0 Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n

Example Rewritten HTTP request:

GET /abc/xyz/index.html HTTP/1.1\r\nHost: www.example5.com\r\nUser-Agent: Mozilla/5.0 Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n

Deleting content at positive offset

NOTEFor more information about offsets, refer to “Explanation of offsets” on page 328.

To configure a request to delete content at a positive offset, follow these steps.

1. Define a CSW rule to search for a prefix "/abc" in URL.

ServerIronADX(config)#csw-rule r12a url prefix "/abc"

Syntax: csw-rule rule-name url prefix prefix-content




3. Specify a primary action.

ServerIronADX(config-csw-mypolicy)#match r12a forward 1025


4. Specify a dependent rewrite action.

ServerIronADX(config-csw-mypolicy)#match r12a rewrite request-delete offset 4 2

Syntax: match rule-name rewrite request-delete offset offset length


The URL prefix "/abc" is matched, offset 0 is at the second "/", which is right after the matched prefix "/abc" in the URL, which is defined in CSW "r12a"; so offset 4 is number "1" which is 4 bytes away after the letter "c". The result is that the 2 bytes containing "12" are deleted in the URL.


GET /abc/xyz12/index.html HTTP/1.1\r\nHost: www.foo.com\r\n



User-Agent: Mozilla/5.0 Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n


GET /abc/xyz/index.html HTTP/1.1\r\nHost: www.foo.com\r\nUser-Agent: Mozilla/5.0 Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n

Deleting content at negative offset


To configure a request to delete content at a negative offset, follow these steps.

1. Define a CSW rule to search for the suffix ".html" at end of URL.

ServerIronADX(config)#csw-rule r12b url suffix ".html"

Syntax: csw-rule rule-name url suffix content





ServerIronADX(config-csw-mypolicy)#match r12b forward 1025



ServerIronADX(config-csw-mypolicy)#match r12b rewrite request-delete neg-offset 11 6

Syntax: match rule-name rewrite request-delete neg-offset offset length

NOTEThe following section assumes you have configured the previous scenario.

When ".html" is matched, offset 0 is the white space after letter "l", letter "l" is neg-offset 1, letter "m" is neg-offset 2, letter "t" is neg-offset 3 and so on. As a result, neg-offset 11 is "_". By counting 6 bytes from left to right starting with "_", you can see that "_index" is to be deleted.


GET /abc/xyz/default_index.html HTTP/1.1\r\nHost: www.example5.com\r\nUser-Agent: Mozilla/5.0 Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n


GET /abc/xyz/default.html HTTP/1.1\r\n



Host: www.example5.com\r\nUser-Agent: Mozilla/5.0 Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n

Deleting a string


To configure a request to delete a sub-string in a CSW rule, follow these steps.

1. Define a CSW rule.

ServerIronADX(config)#csw-rule r13 url exists

Syntax: csw-rule rule-name url exists








ServerIronADX(config-csw-mypolicy)#match r13 rewrite request-delete string "123"

Syntax: match rule-name rewrite request-delete string string-content


The url-exist matches any URL. If found, only string "123" is deleted; if no instance of "123" is found in the URL, the original URL is sent to the server.


GET /abc/xyz123/index.html HTTP/1.1\r\nHost: www.example5.com\r\nUser-Agent: Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n


GET /abc/xyz/index.html HTTP/1.1\r\nHost: www.example5.com\r\nUser-Agent: Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n



Configuring Rewrite request-insert

Content insertion allows the ServerIron ADX to insert any string either right after the matched string found by the CSW rule, or at any specified offset in the content located by the matched CSW rule. Use the following procedures to configure a string insert at a positive offset or a negative offset.


Inserting a string at positive offsetTo configure a request to insert a string after a CSW rule match, follow these steps.

1. Define a CSW rule for the HTTP prefix of the URL.

ServerIronADX(config)#csw-rule r21 url prefix "/abc"








4. Specify a dependent rewrite string.

ServerIronADX(config-csw-mypolicy)#match r21 rewrite request-insert /hello-world

Syntax: match rule-name rewrite request-insert content offset


NOTEIf no offset is defined, the ServerIronADX will always insert at offset 0.

Offset 0 is at the second "/", which is right after matched prefix "/abc", as defined in CSW "r21". The result is that the string "/hello-world" is inserted at the default offset 0, which is after letter "c". The original URL becomes "/abc/hello-world/xyz/index.html".

The highlighted URLs in the following two HTTP request messages show the difference between the original request and the one after being rewritten.






GET /abc/hello-world/xyz/index.html HTTP/1.1\r\nHost: www.example5.com\r\nUser-Agent: Mozilla/5.0 Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n

Inserting a string at negative offsetTo configure a request to insert a string after a CSW rule match, follow these steps.

1. Define a CSW rule for HTTP URL content.

ServerIronADX(config)#csw-rule r22 url prefix /abc/









ServerIronADX(config-csw-mypolicy)#match r22 rewrite request-insert /hello-world neg-offset 5

Syntax: match rule-name rewrite request-insert content neg-offset offset


NOTEIf you want to insert a string at the beginning of a URL, make sure that the string always starts with a "/", or the server that receives the request returns a response of "bad request." This response indicates the format is invalid. The assumption is that the URL always starts with a "/".

The highlighted URLs in the following two HTTP request messages show the difference between the original request and the rewritten request. Offset 0 is at the first "x," which is right after the matched prefix "/ abc/," as defined in CSW "r22". Therefore, negative offset 5 is at the first "/," which is 5 bytes away from and before the "x." The result is that string "/hello-world" is inserted at the first "/", which is the beginning of URL "/abc/xyz/index.html". The original URL becomes "/hello-world/abc/xyz/index.html".






GET /hello-world/abc/xyz/index.html HTTP/1.1\r\nHost: www.example5.com\r\nUser-Agent: Mozilla/5.0 Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n

NOTEWhen inserting a string in an HTTP request, make sure the negative offset is correctly specified. Incorrectly specifying the negative offset (out of range) may result in an improper HTTP request.

Configuring Rewrite request-replace

Content replacement allows you to replace a defined string, or a string that matches a CSW rule. The following procedures explain both methods.

Replacingf a string defined by content ruleTo configure a request to replace a string that matches a CSW rule, follow these steps.


ServerIronADX(config)#csw-rule r31 url exist

Syntax: csw-rule rule-name url exist

2. Define a CSW policy







ServerIronADX(config-csw-mypolicy)#match r31 rewrite request-replace matched-string "/newabc/newxyz/newindex.html"

Syntax: match rule-name rewrite request-replace matched-string new-string

The rule-name variable defines the name of CSW rule.

The matched-string keyword defines the matched string (defined by CSW rule), which is to be replaced.

The new-string variable defines the new string that replaces the previous string.


The url-exist matches the entire URL, so the matched string is the whole URL "/abc/xyz/index.html." It is replaced by the new string "/newabc/newxyz/newindex.html."


GET /abc/xyz/index.html HTTP/1.1\r\n



Host: www.example5.com\r\nUser-Agent: Mozilla/5.0 Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n


GET /newabc/newxyz/newindex.html HTTP/1.1\r\nHost: www.example5.com\r\nUser-Agent: Mozilla/5.0 Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n

Replace a defined stringTo configure a request to replace a specific string in a CSW rule match, follow these steps.


ServerIronADX(config)#csw-rule r32 url pattern "abc"

Syntax: csw-rule rule-name url pattern pattern-content

2. Define a CSW policy






4. Specify a dependent rewrite action

ServerIronADX(config-csw-mypolicy)#match r32 rewrite request-replace string "xyz" "1234"

Syntax: match rule-name rewrite request-replace string old-string new-string

The rule-name variable defines the name of the CSW rule.

The old-string variable defines the string to be replaced, if it can be found in the URL defined by the CSW rule. If the old-string variable is not found, the replacement will not happen.

The new-string variable defines the string with which the old string is to be replaced.


Because the URL contains the pattern "abc," rule r32 will be hit. Then a search for string "xyz" also is positive, so "xyz" will be replaced with string "1234". The following two HTTP request messages show the difference between the original request and the rewritten request.


GET /abc/xyz/index.html HTTP/1.1\r\nHost: www.example5.com\r\nUser-Agent: Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n




GET /abc/1234/index.html HTTP/1.1\r\nHost: www.example5.com\r\nUser-Agent: Netscape/7.02\r\nAccept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n

Configuring redirect

The redirect action causes the ServerIron ADX to redirect a request to an alternate domain, URL, port, or Uniform Resource Identifier (URI) when the specified rule is matched.

For example, the following command causes the ServerIron ADX to redirect a request to the domain brocade.com, URL /home/index.html, and port 8080 when rule r1 is matched.

ServerIronADX(config-csw-policy1)#match r1 redirect "brocade.com" "/home/index.html" 8080

Syntax: [no] match rule-name redirect domain [url | [port status-code] | [url new-port]]

The rule-name variable can be up to 80 characters in length.

The domain variable can be up to 255 characters.

The url variable can be up to 255 characters.

You can optionally specify * (asterisk) for either the domain or url variables. When you do this, the redirected request uses the same domain or URL as in the original request.

For the port variable, you can enter any well-known port name or port number. For the status-code variable, enter any three-digit status code.

For url new-port, enter the new URL and port number to which the request will be redirected.

HTTP redirect status code The ServerIron ADX can be configured to use a temporary or permanent move to suit different application requirements:

• 301 - To redirect the HTTP request to a new, assigned permanent URI.

• 302 (the default) -To redirect HTTP requests to a temporary URI.

To redirect an HTTP request with redirect code 301, enter the following command.

ServerIronADX(config)#csw-policy p1ServerIronADX(config-csw-p1)#match r1 redirect "brocade.com" HTTP 301

Explanation of offsets

NOTEThe offset or neg-offset keyword indicates that insertion or deletion starts after or before the offset of the interested content defined in the matched CSW rule.

In this example, the ServerIron receives the following message.

GET /abc/xyz/index.html HTTP/1.1\r\nHost:www.example5.com\r\nUser-Agent: Mozilla/5.0 Netscape/7.02\r\n


Sample configurations 5

Accept-Charset: ISO-8859-1\r\nCookie: name=brocadenet; userid=12345\r\n\r\n

The following examples show how the offsets work for various rules.

Prefix matchingcsw-rule ruleA url prefix /abc/x

Offset 0 points to "y", which is the next byte after "/abc/x" in the URL.

Suffix matchingcsw-rule ruleB header Host suffix com

Offset 0 points to "\r", which is the next byte after "com" in the value of "Host" header "www.example5.com".

Pattern matchingcsw-rule ruleC header Host pattern foo.

Offset 0 points to "c", which is the next byte after "foo." in the value of "Host" header "www.example5.com".

Exist matchingcsw-rule ruleD1 url exist

Offset 0 points to white space after the letter "l", which is right after the last byte of URL "/abc/xyz/index.html".

Equal matchingcsw-rule ruleE header "Host" equal "www.example5.com"

Offset 0 points to "\r", which is the next byte after "www.example5.com" in the value of "Host" header, "www.foo.com".

Sample configurationsThe HTTP URL Rewrite feature allows the ServerIron to dynamically rewrite URL content in an HTTP request. Also, the HTTP URL Rewrite options allow you to insert, delete, and replace URL content at any offset in an HTTP request.

Seamlessly integrated with ServerIron content switching (CSW), the HTTP URL Rewrite can be configured as a dependent action for primary CSW actions. However, only Forwards and Persists are typically used for HTTP URL Rewrite actions on HTTP requests, because the other actions do not pass requests to servers.

Before you configure an HTTP URL Rewrite, you should be aware of the following benefits and restrictions for this feature:

• You can configure HTTP URL Rewrite and CSW on HTTP, SSL, or any unknown port.

• HTTP URL Rewrite supports HTTP 1.1 Keepalive and TCP Offload.

• HTTP URL Rewrite is an extension of CSW.

• You define HTTP URL Rewrite actions under a CSW policy.


Sample configurations5

• Before you define an HTTP URL Rewrite action, you must define a primary CSW action.

• For each matched CSW rule, you can only define one primary action.

• An HTTP URL Rewrite action works only with a primary action that passes client requests to the servers, such as Forward or Persist actions.

• You can define multiple dependent CSW actions that work together with a primary CSW action.

• Dependent CSW actions include HTTP URL Rewrite, log, client-ip insertion, header insertion, cookie insertion, and deletion.

• HTTP URL Rewrite supports nested CSW rules.

• To enable HTTP URL Rewrite under a VIP, you must enable CSW.

• HTTP URL Rewrite cannot be configured as a default action.

CSW topologyFigure 32 shows a simple CSW network topology.

FIGURE 32 CSW network topology

For the CSW configuration shown in Figure 32, the following rules apply:

• The ServerIron receives incoming traffic on HTTP port, VIP 10.1.1.100.

• The ServerIron is configured with content switching (CSW) rules and policies. Policy 1 is defined to rewrite URL content and forward the request to the Web server 1.

• If a CSW rule is matched, the ServerIron rewrites the HTTP request and forwards it to Web Server 1 with server ID 1025 and IP address 10.1.1.1.

• If no CSW rule is matched, the ServerIron takes the default action, sending the HTTP request to Web Server 2 with server ID 1026 and IP address 10.1.1.2.



Request delete configurationThe following sections describe a full configuration process for an HTTP URL Rewrite, and a configuration process for HTTP URL Rewrite actions.

Request delete configuration example

This section describes how to perform a complete configuration HTTP URL Rewrite, using the content delete option. This scenario uses all of the required steps to configure HTTP URL Rewrite, and identifies the steps that are optional.

The configuration process contains the following segments:

• “Creating a policy with HTTP URL Rewrite” on page 331

• “Configuring real and virtual servers” on page 332

• “Enabling content switching” on page 333

• “HTTP URL Rewrite configuration summary” on page 333

Creating a policy with HTTP URL RewriteTo define a CSW rule and create a CSW policy with HTTP URL Rewrite options, follow these steps.

1. Define a CSW rule to match a URL pattern in an HTTP header.

ServerIronADX(config)#csw-rule r11 url pattern /xyz

Syntax: csw-rule rule-name url pattern url-content

2. Define a CSW rule to match a prefix string in an HTTP header.

NOTEOnly one rule is required for configuring HTTP URL Rewrite.

ServerIronADX(config)#csw-rule r12a header Accept-Charset prefix ISO-

Syntax: csw-rule rule-name header header-content prefix prefix-content




4. Specify a primary action to forward a request to a server ID when a rule is matched.


Syntax: match rule-name forward server id

5. Specify a dependent action and delete the matched string when a rule is matched.

ServerIronADX(config-csw-mypolicy)#match r11 rewrite request-delete matched-string

Syntax: match rule-name rewrite request-delete matched-string

NOTEThe rewrite request-delete matched-string option is an HTTP URL Rewrite action. For more detailed command information, refer to “rewrite request-delete” on page 380.


Sample configurations5

6. Enable logging for this rule.

ServerIronADX(config-csw-mypolicy)#match r11 log

Syntax: match rule-name log

7. Specify a primary action to forward a request to a server ID when a rule is matched.

ServerIronADX(config-csw-mypolicy)#match r12a forward 1025

Syntax: match rule-name forward server id

8. Specify a dependent action and delete at an offset when a rule is matched.

ServerIronADX(config-csw-mypolicy)#match r12a rewrite request-delete offset 4 2

Syntax: match rule-name rewrite request-delete offset offset length

NOTEThe rewrite request-delete offset option is a HTTP URL Rewrite action.


9. Specify default action for client requests that do not match any other rules. Send such requests to the Web server with ID 1026.

ServerIronADX(config-csw-mypolicy)#default forward 1026

Syntax: default forward server-id

Configuring real and virtual serversTo configure the real and virtual servers, follow these steps.

1. Define a real server (1) with an IP address.

ServerIronADX(config)#server real web1 10.1.1.1

Syntax: server real real-server ip-address

2. Define a real HTTP port on the real server.

ServerIronADX(config-rs-web1)#port http

Syntax: port http

3. Define a real server (2) with an IP address.

ServerIronADX(config-rs-web1)#server real web2 10.1.1.2

Syntax: server real real-server ip-address



4. Define a real HTTP port on the real server and exit.

ServerIronADX(config-rs-web2)#port httpServerIronADX(config-rs-web2)#exit

Syntax: port http

Syntax: exit

5. Define a virtual server with an IP address.

ServerIronADX(config)#server virtual-name-or-ip csw-vip 10.1.1.100

Syntax: server virtual-name-or-ip vip-name ip-address

6. Define a virtual HTTP port on the virtual server.

ServerIronADX(config-vs-csw-vip)#port http

Syntax: port http

7. Bind HTTP ports on real servers web1 and web2 to the virtual port HTTP.

ServerIronADX(config-vs-csw-vip)#bind http web1 http web2 http

Syntax: bind http real-server http vip-name

Enabling content switchingTo enable content switching, follow these steps.

1. Bind the policy to virtual HTTP port on virtual server.

ServerIronADX(config-vs-csw-vip)#port http csw-policy mypolicy

Syntax: port http csw-policy policy-name

2. Enable CSW on the virtual port.

ServerIronADX(config-vs-csw-vip)#port http csw

Syntax: port http csw

HTTP URL Rewrite configuration summaryThe following example shows a summary of the configuration steps.

#csw-rule r11 url pattern /xyz#csw-rule r12a header Accept-Charset prefix ISO-

#csw-policy mypolicy #match r11 forward 1025 #match r11 rewrite request-delete matched-string #match r11 log #match r12a forward 1025 #match r12a rewrite request-delete offset 4 2 #default forward 1026

#server real web1 10.1.1.1 #port http#server real web2 10.1.1.2 #port http


Layer 7 content switching on HTTP response5

#server virtual-name-or-ip csw-vip 10.1.1.100 #port http #port http csw-policy mypolicy #port http csw #bind http web1 http web2 http

Layer 7 content switching on HTTP responseThe ServerIron ADX can perform content rewrite on the server responses. In other words, the ServerIron can not only modify requests in the forward direction, but also the responses in reverse direction. The HTTP response is divided into the "header" part and the "body" part. The ServerIron can selectively rewrite the header, body, or both.

Response header rewrite The response header rewrite feature is typically required in an SSL-Offload environment when the real servers send redirect messages to the incoming clients. Figure 33 shows such a scenario when the Real-Server is not aware of the SSL-Offload but sends a redirect using HTTP. The ServerIron does not change the response and sends it to the client. The Client, as a result, sends another request using HTTP, and as a result, suddenly moves from a secure HTTPS to HTTP.

FIGURE 33 HTTP response header rewrite

A ServerIron can be programmed to modify such responses and replace "http://" with "https://". This feature can be applied selectively based on the response code and the embedded URL. For example, the ServerIron can be programmed to replace only response codes 301 and 302, and only for URLs matching "http://www.example6.com".

In general, this feature is used for modifying the redirect URLs in response codes 301 and 302. However, it is not limited to modifying redirects and in theory can be configured to modify any other part of the HTTP-header in any other response code.

Configuring HTTP header response rewriteTo enable response header-rewrite, follow these steps.

1. Create a CSW rule specifying the request rule or response codes to be acted upon."

2. Create a CSW rule specifying the string to be modified.


Layer 7 content switching on HTTP response 5

3. Create a CSW policy.

4. Bind the CSW policy to the virtual server port.

Creating a CSW rule specifying the header response codes

In this step, the header response codes are specified, and a response is inspected only if those codes are found. For example, to specify the redirect response code, the following configuration is required.

ServerIronADX(config)#csw-rule r2 response-status-code 200 400

Syntax: [no] csw-rule rule-name response-status-code low-bound high-bound

Creating a CSW rule specifying the string to be modified

In this step, a CSW-Rule is configured that specifies the string to be matched in a given header. For example, to match the string the redirect messages typically have response codes of 301 or 302, and the new URL is specified in the header "Location."

For example, to match the redirect location "http://www.example6.com," the following rule is required.

ServerIronADX(config)#csw-rule r11 response-header "Location" pattern "http://www.example6.com"

Syntax: [no] csw-rule rule-name response-header header-name pattern pattern-to-be-found

Creating a CSW policy

When the rules have been defined, they need to be added to a CSW policy. The policy type response-rewrite must be used so as to distinguish the response-rewrite policy from the original CSW policies, like request-rewrite.

The two rules configured in step 1 and step-2 are added to this policy. The first rule ensures that the policy acts only on responses with response codes 301 or 302. The second rule matches the string "http://www.example6.com" and replaces it with "https://www.example6.com." The offset and length defines the portion of the original match that has to be replaced. The example below shows the rewriting of the entire string. Alternatively, only the first four characters can also be modified, in which case the offset would be 0, with length 4, and the new string would be "https."

ServerIronADX(config)#csw-policy "p1" type response-rewriteServerIronADX(config-rew-p1)#match "r1" rewrite response-insert headerServerIronADXconfig-rew-p1)#match "r11" rewrite request-replace string "https://www.example6.com/" offset 0 length 19

Syntax: [no] csw-policy policy-name type response-rewrite

Binding a CSW policy to the virtual server port

The final step is to apply the CSW policy to the incoming traffic by binding it to a virtual port. This type of policy is usually applied on port SSL, but can also be applied on port HTTP.

ServerIronADX(config)#server virtual-name-or-ip v1 10.1.1.10ServerIronADX(config-vs-v1)#port ssl response-rewrite-policy "p22"

Syntax: port port-type response-rewrite-policy policy-name


Layer 7 content switching on HTTP response5

In this configuration, the ServerIron rewrites the HTTP response. Whenever response code 301 or 302 appears in the header, together with a redirect URL http://www.example6.com (signified by the Location header), the ServerIron replaces the URL with https://www.example6.com. In other words, "Location: http://www.example6.com" becomes "Location: https://www.example6.com."

Response body rewriteThe response body rewrite feature can be used in multiple scenarios. The most commonly used scenario is when a web-site wants a seamless upgrade to SSL-Offload. Before this release, the Real-Servers had to change embedded links using SSL to be replaced from "http://" to "https://", but now instead of making all these changes on the real-servers, they can be made on the ServerIron.

NOTEResponse body rewrite only works for uncompressed contend delivered from the real servers.

Configuring HTTP body response rewriteTo enable response-header-rewrite, follow these steps:

1. Creating a CSW-Rule specifying the response codes to be acted upon.

2. Creating a CSW-Rule specifying the URLs to be modified.

3. Creating a CSW-Policy.

4. Binding a CSW-Policy to the virtual-server port.

Creating a CSW rule identifying requests whose responses must be modified

In this step, the requests are identified, and responses to the requests are eligible for response modifications. To specify all requests with responses that need to be modified, use the following command.

ServerIronADX(config)#csw-rule r2 url exists

Syntax: csw-rule rule-name url exists

csw-rule r1 response-status-code 301 302csw-rule r11 response-header "Location" pattern "http://www.example6.com"csw-policy "p1" type response-rewrite match "r1" rewrite response-insert header match "r11" rewrite request-replace string "https://www.example6.com/" offset 0 length 19

server real rs1 10.1.1.101 port http port http url "HEAD /"


Layer 7 content switching on HTTP response 5

Creating a CSW rule specifying the string to be modified

In this step, a CSW rule is configured that specifies the string to be matched in the response body. For example, if you intend to modify http://www.example6.com to https://www.example6.com, use the following command.

ServerIronADX(config)#csw-rule r21 response-body pattern "http://www.example6.com/"

Syntax: no] csw-rule rule-name response-body pattern pattern to be found

Creating a CSW policy

After you define the rules, you must add the rules to a CSW policy. The policy type response-rewrite must be used to distinguish the response-rewrite policy from the original CSW policies such as request-rewrite.

When the two rules configured in step 1 and step 2 are added to this policy, the first rule ensures that the policy acts on all HTTP requests. The second rule matches the string "http://www.example6.com" in the response body and replaces it with "https://www.example6.com". The offset and length defines the portion of the original match that has to be replaced. The example below shows the rewriting of the entire string. Alternatively, only the first four characters can be modified. in this case, the offset would have been 0 with length 4 and the new string "https."

ServerIronADX(config)#csw-policy "p22" type response-rewriteServerIronADX(config-rew-p22)#match "r2" response-body-rewrite ServerIronADX(config-rew-p22)#match "r21" rewrite response-body-replace "https://www.example6.com/" offset 0 length 19

Syntax: csw-policy policy-name type response-rewrite

Binding a CSW-policy to the virtual-server port

The final step is to apply the CSW policy on the incoming traffic by binding it to a virtual port. This type of policy is usually applied on port SSL, but can also be applied on port HTTP.

ServerIronADX(config)#server virtual-name-or-ip v1 10.1.1.10ServerIronADX(config-vs-v1)#port ssl response-rewrite-policy "p22"

Syntax: port port-type response-rewrite-policy policy-name

Using show commands

To show statistics of this feature, enter a command such as the following on the BP console.

ServerIronADX#show csw-policy p1

Syntax: show csw-policy policy-name


Using multiple cookies under virtual server port5


This configuration replaces all references to http://www.example6.com with https://www.example6.com in all response data. In other words, the data "href='http://www.example6.com/index.html" becomes "href=https://www.example6.com/index.html".

Using multiple cookies under virtual server port

Configuring multiple unique cookie insertion with cookie pathThis release adds support for multiple cookies. Based on a URL or any content information contained in a HTTP request, this feature allows ServerIron to introduce to the client user agent a unique cookie with different attributes, such as domain, path, and expiration time.

In previous releases, cookie insertion was configured under a VIP. With more customers having multiple sites hosted per VIP, a single cookie to accommodate all the sites is not sufficient. This feature extends the current implementation of cookie insertion on ServerIron, so that multiple cookies for different sites and applications can be inserted.

NOTEThe following commands is configured under a CSW policy.

Configuring cookie insertion when a particular CSW rule is hit

To configure cookie insertion when a particular CSW rule is hit, use the following command.

Syntax: match rule-name rewrite cookie-insert [cookie-name [domain [path [age]]]]

If l7-dont-use-gateway-mac is configured along with a CSW rule for cookie insertion, the embedded link in a web page on the real server (which could be an image) will not appear.

csw-rule r2 url existscsw-rule r21 response-body pattern http://www.example6.com/csw-policy "p1" type response-rewrite match "r2" response-body-rewrite match "r21" rewrite response-body-replace "https://www.example6.com/" offset 0 length 19



server virtual-name-or-ip v1 10.1.1.10 port ssl port ssl response-rewrite-policy p1 bind ssl rs1 http rs2 http


Using multiple cookies under virtual server port 5

The reason is because the fetch request for the image is second request and it has a cookie embedded. This request does not need insert cookie, so it will go through a normal Layer 7 forwarding path. This will need spoofing to be configured in order to forward the packet.

The first request does not have cookie. So it will go through cookie insertion (content rewrite) code path. This one can take care of l7-dont-use-gateway-mac command and does not need spoofing configured. But for l7-dont-use- gateway-mac command to work, spoofing is required

NOTESpoofing can be configured with the port port-number spoofing command under the virtual server configuration.

This can also be achieved by configuring l3-default-gateway.

Configuring cookie insertion in default mode (when no CSW rule is hit)

To configure cookie insertion in default mode (when no CSW rule is hit), use the following command.

Syntax: default rewrite insert-cookie [cookie-name [domain [path [age]]]]

The cookie-name variable specifies the name of the cookie to be inserted.

The domain variable specifies the attribute domain for the cookie to be inserted. If the domain variable is not configured or it is configured to be "*," the default domain for the cookie inserted in the HTTP response will be the same as the one in the previous request.

The path variable specifies the attribute path for the cookie to be inserted. If the path variable is not configured or it is configured to be "*," then "/" is defined for the cookie path.

The age variable specifies how many minutes the browser takes to expire the cookie to be inserted. If the age variable is not configured, the cookie will expire when the browser is closed. If the age variable is configured to be 0, the browser will age out the cookie immediately.

NOTEThe cookie-name variable is required, while the path, domain, and age variables are optional.

SpecificationsCLI commands on ServerIron have a limitation on the total length of each command, When a command includes many keywords or values, the attributes of path or domain can be too long. The following are the internal system limitations for some attributes introduced by this command:

• cookie-name: Maximum length is 80 bytes.

• path: Maximum length is 255 bytes.

• domain: Maximum length is 80 bytes.

• age:Integer between 0 and 0x1FFFFFFF.

Configuration guidelines

Cookie insertion is typically configured together with cookie switching. If a specific cookie with valid value is found and the associated action can be taken, the ServerIron will take action based on the cookie value; otherwise, it follows other matched rules, in which possibly a cookie insertion is triggered.


Using multiple cookies under virtual server port5

The following are the steps to configure the cookie insertion with cookie switching:

• Configure CSW rules and policy

• Bind the CSW policy to a VIP

• Enable CSW on the VIP

Example

The ServerIron does cookie switching based on the cookie value of "ServerID" or "biz" defined in either rule1 or rule2.

If both rule1 and rule2 are not hit but rule3 is hit, it will forward the request to server group 10 and insert a cookie with name "biz", with path being "business".

If no rule is hit, ServerIron will take the default action. It will forward the request to server group 1 and insert a cookie with name "ServerID", which expires in 60 minutes.

NOTEMake sure that the system time is configured when you configure cookie age.

csw-rule rule1 header "Cookie" search "ServerID="csw-rule rule2 header "Cookie" search "biz="csw-rule rule3 url prefix "/business"csw-policy policy1 match rule1 persist offset 0 length 0 group-or-server-id match rule2 persist offset 0 length 0 group-or-server-id match rule3 forward 10 match rule3 rewrite insert-cookie "biz" "*" "/business" default forward 1 default rewrite insert-cookie "ServerID" "*" "*" age 60

server virtual-name-or-ip test 10.2.2.222 port default disable port http port http csw-policy "policy1" port http csw port http keep-alive bind http rs1 http

server real rs1 10.1.1.1 port http port http url "HEAD /" port http server-id 1100 port http group-id 1 1 port 8080 port 8080 server-id 1208 port 8080 group-id 10 10server virtual-name-or-ip test 10.2.2.2 port default disable port http port http csw-policy "policy1" port http csw port http keep-alive bind http rs1 http rs1 8080


Server passive cookie persistence 5

Server passive cookie persistence This feature provides connection persistence for flows where a cookie is dynamically injected by the backend application server. With this feature enabled, the ServerIron ADX monitors the server reply and looks for a cookie with a specified name. The ServerIron ADX then builds a hash value based on the content of the cookie. This hash value is then stored in a sticky session together with the real server that is responsible for the cookie. Client requests are then monitored for the cookie value associated with the server and a hash value is generated. Where this hash value is equal to the value stored in the sticky session with the real server, client requests are sent to that real server.

For example in Figure 34, a client sends an initial request to the HTTP port at VIP address: “10.10.10.1”. The real server at IP address “172.16.0.5”, sends a reply to the client containing a cookie named “JSESSIONID” with a value of “0123456789abcdefg012345643352256”. The ServerIron ADX makes a hash value from “0123456789abcdefg012345643352256” and creates a session table entry. All subsequent requests from the client that contain the “JSESSIONID” cookie with the value generated by the real server in its reply are assigned to that real server.

FIGURE 34 Server passive cookie example


Server passive cookie persistence5

Configuring server passive cookie persistenceThe server passive cookie persistence feature is implemented by configuring CSW rules and policies as described in the following:

• Create a CSW rule to match the server response

• Create a CSW rule to match the client request

• Specify a CSW action to create persist

• Specify a CSW action to perform persistence lookup and retrieve real server information

Creating a CSW rule to match the server response

To create a CSW rule to match the server response, use the following command.

ServerIronADX(config)#csw-rule r1 response-header “set-Cookie” pattern “JSESSIONID”

Syntax: [no] csw-rule rule-name response-header header-name pattern search-string


The header-name variable specifies HTTP header field to be matched in an HTTP response from a real server.

The search-string variable specifies the string within the header-name variable that will be matched in the HTTP response from a real server.

Creating a CSW rule to match the client request

To create a CSW rule to match the client request, use the following command.

ServerIronADX(config)#csw-rule r2 header “Cookie” pattern “OutlookSession”

Syntax: [no] csw-rule rule-name header header-name pattern search-string


The header-name variable specifies the HTTP header field to be matched in an HTTP request from a client.

The search-string variable specifies the string within the header-name variable that will be matched in an HTTP request from a client.

Specifying a CSW action to create persistence information

To specify a CSW action to maintain persistency information, use the following command.

ServerIronADX(config)#csw-policy p1ServerIronADX(config-csw-policy-p1)#match r1 passive-persist offset 0 length 11

Syntax: [no] match rule-name passive-persist offset persistence-string-offset length persistence-string-length

The rule-name is the name of a previously configured CSW rule that was defined to match a server response.


Server passive cookie persistence 5

The persistence-string-offset variable specifies the number of characters that will be skipped directly after the search-string matched in the specified CSW rule. Normally this value is 0 (zero) which places the start point at the character that is right after the string. As an example, you can configure a search string to “JSESSIONID” as specified for “r1, with an offset of “0”. Where the string found is “JSESSIONID=0123456789abcdefg012345643352256", an offset of “0” will mean that the hash string will start with “=”. If the offset is “7” the string will be parsed beginning with the integer “6”.

Once the offset point is set by the persistence-string-offset, the system will parse the search-string matched in the specified CSW rule up-to the number of characters defined by the value of the persistence-string-length variable. The value of the persistence-string-length variable must be greater than 0 (zero). If the value of the length variable extends beyond the length of the search-string, the system will look to the end of the string to define the string used for hashing.

For example: if the search string is “JSESSIONID” as described in the preceding chapter, and the offset is “0”, the string will be parsed beginning with the “=”. If the persistence-string-length is set to “7”, the string used will be “0123456”.

Specifying a CSW action to perform persistence lookup and retrieve real server information

To specify a CSW action to perform persistency information lookup and use stored real server information to forward requests, use the following command.

ServerIronADX(config)#csw-policy p1ServerIronADX(config-csw-policy-p1)#match r2 persist offset 0 length 11 passive-persist

Syntax: [no] match rule-name persist offset persistence-string-offset length persistence-string-length passive-persist

The rule-name is the name of a previously configured CSW rule that was defined to match a client request.

The persistence-string-offset variable specifies the number of characters that will be skipped after the start point of the search-string matched in the specified CSW rule. Normally this value is 0 (zero) which places the start point at the beginning of the string. For example: if the search string is “OutlookSession” as specified in r1, and the offset is “0”, the string will be parsed beginning with the capital “O” in “OutlookSession”. If the offset is “7” the string will be parsed beginning with the capital “S” in “Session”.

Once the offset point is set by the persistence-string-offset, the system will parse the search-string matched in the specified CSW rule up-to the number of characters defined by the value of the persistence-string-length variable. The value of the persistence-string-length variable must be greater than 0 (zero). If the value of the length variable extends beyond the length of the search-string, the system will look to the end of the string to define the string used for hashing. For example: if the search string is “OutlookSession” as specified in r1, and the offset is “0”, the string will be parsed beginning with the capital “O” in “OutlookSession”. If the persistence-string-length is set to “7”, the string used will be “Outlook”.


Server and server port persistence with CSW nested rules5

ExampleThe following example operates in a configuration much like the example shown in Figure 34 with the following operation:

1. The Client request the following URL: www.test.com

2. The server responds with a page and performs “Set-Cookie: PSrvrID=1234567”

The page contains several URL such as: href=”test/nextpage.html?PSrvrID=1234567"

3. The Client clicks on the link: www.test.com/test/nextpage.html?PSrvrID=1234567

If cookies are enabled, the Client sends: “Cookie: PSrvrID=1234567”

If cookies are disabled, NO cookie is sent back.

4. The load balancer analyzes the incoming request as described:

If “cookie” is found in the header (Cookie:), the cookie value is looked up in the session table for the session bound to the same server.

If no cookie is found, the URL can be analyzed. the cookie name is also found after the “?” value is found. It is also looked up in the session table for the session bound to the same server.

Sample configuration

The following can be used to configure the previous example.

ServerIronADX(config)#csw-rule "response-cookie" response-header "Set-Cookie" pattern "PSrvrID="ServerIronADX(config)#csw-rule "uri" url pattern "PSrvrID="ServerIronADX(config)#csw-rule "forward-cookie" header "Cookie" pattern "PSrvrID="ServerIronADX(config)#csw-policy "passive1"ServerIronADX(config-csw-policy-passive1)#match "response-cookie" passive-persist offset 0 length 7ServerIronADX(config-csw-policy-passive1)#match "forward-cookie" persist offset 0 length 7 passive-persistServerIronADX(config-csw-policy-passive1)#match "uri" persist offset 0 length 7 passive-persist

You must then bind the csw-policy to a virtual server port.

Server and server port persistence with CSW nested rulesThis section contains the following sub-sections:

• “Configuring server and server port persistence with CSW nested rules” on page 345

• “Configuring persist on the nested rule” on page 345

• “Configuring persist on the real port” on page 345

NOTECSW nested rules are not supported in a csw response rewrite policy.


Server and server port persistence with CSW nested rules 5

Configuring server and server port persistence with CSW nested rulesThis section describes the support of CSW rewrite/persist on nested rule and persist on real server ports.

Currently, CSW supports rewrite or persist action on simple rules. The rewrite or persist action on nested rules is not supported, because the place of rewrite or persist action can not be decided on nested rule. This new feature adds a new CLI to specify a base rule within nested one that rewrite or persist action can be based on.

Also, the current CSW supports the persistence on the group or server ID. Support of persistence on the real server port gives you more granular control.

This feature is to be used with persistence on the group or server ID and is useful when the customer has multiple ports configured on the same group or server, and also wants to direct the request to a particular port instead of load balancing among all the ports.

Persist or rewrite actions can be performed when a nested rule matches, and the location of persistence or rewrite string is determined by a master rule within the nested rule.

Configuring persist on the nested ruleTo create a csw nested rule, enter a command such as the following.

ServerIronADX(config)#csw-rule r1 url pattern "pweb"ServerIronADX(config)#csw-rule r2 url pattern "jsession"ServerIronADX(config)#csw-rule n1 nested-rule "r1&&r2" master-rule r2

Syntax: [no] csw-rule rule-name nested-rule rule-logic-string master-rule rule-name

NOTEIf a master rule is not specified, the default master in the first rule is the nested rule.

NOTEIf a master rule is not present when the nested rule matches, the persist or rewrite action cannot be performed. It will be treated as nested rule not matched.

Configuring persist on the real portTo specify the real port for a persist action, enter a command such as the following.

ServerIronADX(config)#csw-policy p1ServerIronADX(config-csw-p1)#match n1 persist offset 22 length 2 group-or-server-id real-port 10500

Syntax: [no] match rule-name persist offset offset length offset [[persist-method [real-port port [port-failover|fail-close]]] [secondary]]

NOTEThe real port and the failover modes can only be specified when the persist-method variable is group-or-server-id.


Server and server port persistence with CSW nested rules5

The three modes when the specified real port is not available are:

• Default: Layer 4 load balancing is performed.

• Port-failover: The ServerIron fails over to the same port number configured on the virtual port. When there is no real port to be failed over, the client connection is closed.

• Fail-close: The ServerIron immediately closes the client connection.

Usage example

The customer needs the following request:

• Two real servers, 192.168.1.100 and 192.168.1.101.

• Each server has a different application listening on different ports: 10500 and 10520.

• Each server is configured to a different group, 30 and 31.

• The request with “pweb” and “jsession=groupid”embedded in the URL is directed to the specified group

The configuration is as follows.

• For configuring the real server, enter the following commands:

ServerIronADX(config)#server real-name-or-ip rs1 192.168.1.100ServerIronADX(config-rs-rs1)#port 10500 group-id 20 20 30 30ServerIronADX(config-rs-rs1)#port 10520 group-id 21 21 30 30ServerIronADX(config-rs-rs1)#exitServerIronADX(config)#server real-name-or-ip rs2 192.168.1.101ServerIronADX(config-rs-rs2)#port 10500 group-id 20 20 31 31ServerIronADX(config-rs-rs2)#port 10520 group-id 21 21 31 31ServerIronADX(config-rs-rs2)#exit

• For configuring the CSW rule, enter the following commands:

ServerIronADX(config)#csw-rule r1 url pattern "pweb"ServerIronADX(config)#csw-rule r2 url pattern "jsession="ServerIronADX(config)#csw-rule n1 nested-rule "r1&&r2" master-rule r2

• For configuring the CSW policy, enter the following commands:

ServerIronADX(config)#csw-policy p1ServerIronADX(config-csw-p1)#match n1 persist offset 0 length 2 group-or-server-id real-port 10500

• For configuring the virtual server, enter the following commands:

ServerIronADX(config)#server virtual-name-or-ip vip1 10.10.10.100ServerIronADX(config-vs-vip1)#bind http rs1 10500 rs1 10520ServerIronADX(config-vs-vip1)#bind http rs2 10500 rs2 10520ServerIronADX(config-vs-vip1)#port http csw-policy p1

The result is as follows:

• If the request has the string "pweb" and also string "/jsession=30" embedded in the url, Then the rule n1 will be matched and SI will choose to connect to the rs1 (group 30) and the port 10500

• If the port 10500 on rs1 is not available, the client request fails over to the port 10500 on rs2.


Displaying CSW information 5

Displaying CSW informationYou can display the CSW information as described in the following sections.

• “Displaying header information”

• “Displaying CSW rule information”

• “Displaying CSW policy information”

• “Displaying the statistics for all HTTP content rewrites”

• “Displaying Layer 7 switching statistics”

• “Displaying the hash-based server selection for CWS policies”

Displaying header informationTo display information about the HTTP headers encountered in a Layer 7 content switching configuration, enter the show csw-hdr-info command.

Syntax: show csw-hdr-info

ServerIronADX#show csw-hdr-infoUnknown header listName :Hdr Tab Ind :Ref Co------------------------------------------------------------Cookie: :0 :1Unknown header count: 1

Known header listName :Hdr Tab Ind------------------------------------------------------------Connection: :10Transfer-Encoding: :11Content-Length: :12Host: :13Cookie: :14Pragma: :15Cache-Control: :16Known header count: 7

XML tag listName :Tab Ind :Ref Co------------------------------------------------------------banner1 :0 :4banner2 :1 :1banner3 :2 :1banner4 :3 :1banner5 :4 :1banner6 :5 :1banner7 :6 :1banner8 :7 :1volume :8 :9XML tag count: 9



Table 29 describes the information displayed by the show csw-rule command.

To display detailed information for a specified rule, enter the show csw-rule detail command, as follows.

Syntax: show csw-rule rule-name detail

TABLE 29 Output from the show csw-rule command

Field Description

Rule Count The number of Layer 7 content switching rules configured on the device.

Rules Allocated The total number of rules allocated.

Rules Deleted The total number of rules deleted since the ServerIron ADX was started.

Rule Name The name of each rule.

Rule Type The type of rule: HTTP method, HTTP version HTTP header, URL, or XML tag.

Data fields The specification for the rule; that is, the content that the rule matches.

Ref C The number of nested rules and policies using this rule.

Prot The protocol of the packets matched by the rule.

ServerIronADX#show csw-rule volume1 detailRule Name :volume1Rule Type :xml-tagHeader :volumeOperator :equalsValue :Volume Icase-insensitive:FALSE

Ref cnt :1

Sub Rule cnt :1Sub Rules :volume1

Before Minterm ReductionMin term mask :0x00000002Min terms :1

After Minterm ReductionMin term cnt :1Minterms :volume1

Hdr/Meth Ind :8



Table 30 defines the information displayed by the show csw-rule detail command.

TABLE 30 Output from the show csw-rule detail command

Field Description

Rule Name The name of the rule.

Rule Type The type of rule: HTTP method, HTTP version HTTP header, URL, or XML tag.

Header The HTTP header matched by the rule.

Operator The operator used to match the content: exists, prefix, suffix, pattern, equals, or search

Value The content matched by the rule.

Ref cnt The number of nested rules and policies using this rule.

Sub Rule cnt If this is a nested rule, the number of rules referring to this one.

Sub Rules If this is a nested rule, a list of the rules that refer to this rule.

Before Minterm Reduction

Min term mask

Number of minterms for the expression.

Min terms List of minterms.

After Minterm Reduction

Min term cnt Number of minterms for the expression.

Minterms List of minterms.

Hdr/Meth Ind Index into the header in the method table.



Displaying CSW policy informationTo display information about a Layer 7 content switching policy, enter the show csw-policy server-sw command on the BP.

Syntax: show csw-policy server-sw

Table 31 defines the fields shown in the screen display.

TABLE 31 Output from the show csw-policy command

Field Description

Policy Name The name of the policy.

Reference Count Number of VIPs using this policy.

Rule Name The rules configured under the policy.

Act The action specified for each rule.

Data fields The specification for the rule; that is, the content that the rule matches.

Flags Information about the content-rewrite actions for the rule, if configured.

Hit Cnt The number of times a rule matched.

ServerIronADX#show csw-policy server-swPolicy Name :server-sw

Policy Type:Content SwitchingPolicy Index:4Reference Count:0total received packet:0created session:0total scanned packet:0no session drop:0no session frag drop:0send mirror ip packet:0send mirror packet:0send redirect packet:0case-sensitive:FALSE

Action code description:fwd: forwardrst: reset-clientper: persistrdr: redirecterr: reply-error got: gotorwt: rewritemir: mirrorlog: logcon: countdrp: droprec: vir-resetred: cont-redmlp: mirror-ipunk: unknown

Flag description:A: insert-cookieB: delete-cookie C: destroy-cookieD: req-ins-hdrE: req-ins-client-ipF: resp-ins-hdrG: delete-contentH: insert-content I: modify-contentL: log

Rule Name |Act|Data1 |Data2 |Data3 |Flags |Hit Cnt------------------------------------------------------------------------------url1024 |fwd|1024 | |N/A |_______ |2url1025 |fwd|1025 | |N/A |_______ |3default |fwd|1 | |N/A |_______ |10-------------------------------------------------------------------------------



To display detailed information about a policy, enter the show csw-policy detail command, as follows.

Syntax: show csw-policy policy-name detail

In addition to the information shown in Table 31, the show csw-policy detail command displays the fields as defined in Table 32.

TABLE 32 Output from the show csw-policy detail command

Field Description

Offse The offset into the minterm table.

Total Rule Count The total number of rules in the policy.

Simple Rule Count The total number of simple (not nested) rules used in the policy.

Minterm Count The number of minterms.

ServerIronADX#show csw-policy server-sw detailPolicy Name :server-sw

Policy Type:Content SwitchingPolicy Index:4Reference Count:1total received packet:0created session:0total scanned packet:0no session drop:0no session frag drop:0send mirror ip packet:0send mirror packet:0send redirect packet:0case-sensitive:0

Action code description:fwd: forwardrst: reset-clientper: persistrdr: redirecterr: reply-error got: gotorwt: rewritemir: mirrorlog: logcon: countdrp: droprec: vir-resetred: cont-redmlp: mirror-ipunk: unknown

Flag description:A: insert-cookieB: delete-cookie C: destroy-cookieD: req-ins-hdrE: req-ins-client-ipF: resp-ins-hdrG: delete-contentH: insert-content I: modify-contentL: log

Rule Name |Act|Offse|Data1 | Data2|Data3 |Flags |Hit Cnt---------------------------------------------------------------url1024 |fwd|0 |1024 | |N/A |_______ |0url1025 |fwd|1 |1025 | |N/A |_______ |0default |fwd|0 |1 | |N/A |_______ |0---------------------------------------------------------------

Total Rule Count :1Simple Rule Count :1Minterm Count :1Database Count :1XML Tag Count :0Parse Mask :0x00020000Parse Tags :url

Vip Bindings :10.168.28.150 [80]



Displaying the statistics for all HTTP content rewritesYou can use the show l7-rewrite-info command to display the statistics for all HTTP content rewrites. Using this command on the Management Processor (MP) shows the results of all HTTP content rewrites for both the MP and the BPs. Using this command on a BP (the web switching CPU) shows the results for the BP only.

To display the statistics for all HTTP content rewrites, enter the show l7-rewrite-info command.

Syntax: show l7-rewrite-info

Table 33 defines the fields shown in the screen display.

Database Count The number of search databases.

XML Tag Count The number of XML tags used in the policy.

Parse Mask Mask to indicate the parsing information.

Parse Tags The header or XML tags to be parsed.

Vip Bindings The list of VIPs and port numbers using this policy.

TABLE 33 Layer 7 Rewrite information

Field Description

HTTP Content Rewrites Shows the memory slots used to perform HTTP content rewrites.

Total Allocated The total number of allocation times of memory slots used to perform content rewrites.

Total Freed The total number of freed times of memory slots used for content rewrites.

Used Now The number of memory slots that are currently used to perform content rewrites.

Allocation Failures The number of failures that occurred while allocating memory for content rewrites.

Content Rewritings Done in HTTP Requests

This section displays information related to cookie deletions, header insertions, and client IP insertions.

TABLE 32 Output from the show csw-policy detail command (Continued)

Field Description

ServerIronADX#show l7-rewrite-info

HTTP Content Rewrites: Total Allocated: 9 Total Freed: 5 Used Now: 4 Allocation Failures: 0

Content Rewritings Done in HTTP Requests: Cookie Deleted: 0 Cookie Deletion Err: 0 Cookie Destroyed: 1 Cookie Destroy Err: 0 Header Insertion: 2 Header Insertion Err: 0 Client IP Insertion: 2 Client IP Insertion Err: 0

Content Rewritings Done in HTTP Responses: Cookie Inserted: 1 Cookie Insertion Err: 0 Header Insertion: 0 Header Insertion Err: 0

Total Memory Already Consumed: 64 KB.



Displaying Layer 7 switching statistics To display Layer 7 switching statistics, enter the show server proxy command at any level of the CLI.

Syntax: show server proxy

Table 34 defines the fields in the screen display.

Cookie Deleted The total number of cookies deleted in HTTP requests.

Cookie Deletion Err The number of errors that occurred when deleting cookies in HTTP requests.

Cookie Destroyed The number of cookies destroyed during HTTP requests.

Cookie Destroy Err The number of errors that occurred while destroying cookies in HTTP requests.

Header Insertion The total number of headers inserted in HTTP requests.

Header Insertion Err The number of errors that occurred when inserting headers in HTTP requests.

Client IP Insertion The total number of client IP headers inserted in HTTP requests.

Client IP Insertion Err The number of errors that occurred when inserting client IP headers in HTTP requests.

Content Rewritings Done in HTTP Responses

This section contains information about cookie and header insertions.

Cookie Inserted The total number of cookies inserted in HTTP responses.

Cookie Insertion Err The number of errors that occurred when inserting cookies in HTTP responses.

Header Insertion The total number of headers inserted in HTTP responses.

Header Insertion Err The number of errors that occurred when inserting headers in HTTP responses.

Total Memory Already Consumed

The total amount of memory allocated for HTTP content rewrites.

TABLE 34 Layer 7 Switching statistics

Field Description

Slot alloc Number of proxies allocated

Curr free slot Number of proxies possible

Slot freed Number of proxies finished

TABLE 33 Layer 7 Rewrite information (Continued)

Field Description

ServerIronADX#show server proxy Slot alloc = 0 Curr free slot = 99999 Slot freed = 0 Slot alloc fail = 0 Pkt stored = 0 Max slot alloc = 0 Pkt freed = 0 Fwd Stored pkt = 0 Session T/O = 0 Sess T/O pkt free = 0 Session del = 0 Sess del pkt free = 0 DB cleanup cnt = 0 DB cleanup pkt free = 0 Serv RST to SYN = 0 Send RST to C = 0 URL not in 1st pkt = 0 Cookie not in 1st pk = 0 URL not complete = 0 Cookie not complete = 0 Sess T/O rev Sess 0 = 0 Sess T/O Sess diff = 0 Dup SYN Sess diff = 0 Curr slot used = 0 Curr pkt stored = 0



Displaying the hash-based server selection for CWS policiesTo display the hash-based server selection for CWS policies that are configured with CWS rules which have content that can be hashed, use the show server hash command from the BP console.

Syntax: rconsole slot# BP#

Syntax: show server hash [virtual-server-name]

The optional virtual-server-name variable is the name of a specific virtual server. If you do not specify a virtual server, the show server hash command displays the hash bucket information for all virtual servers.

Slot alloc fail Number of proxy allocation failures

Pkt freed Number of packets stored by proxy

Max slot alloc Maximum number of concurrent proxies

Pkt freed Number of packets freed by proxy

Fwd Stored pkt Number of stored packets sent to server

Session T/O Number of session timeouts

Sess T/O pkt free Number of stored packets freed due to session timeout

Session del Number of sessions freed by proxy

Sess del pkt free Number of stored packets deleted when session was freed

DB cleanup cnt Proxy cleanup count

DB cleanup pkt free Number of stored packets freed during proxy cleanup

Serv RST to SYN Number of times the server sent RST to TCP SYN

Send RST to C Number of times the ServerIron ADX sent RST to client

URL not in 1st pkt Number of times the URL string was not in the first packet

URL not complete Number of times the URL string was not complete

Cookie not in 1st pk Number of times the Cookie header was not in the first packet

Cookie not complete Number of times the Cookie header was not complete

Sess T/O rev Sess 0 Number of session timeouts with no reverse session

Sess T/O Sess diff Number of session timeouts, internal proxy error

Dup SYN Sess diff Number of duplicate SYNs received, internal proxy error

Curr slot used Number of existing proxies

Curr pkt stored Current number of packets stored by proxy

TABLE 34 Layer 7 Switching statistics (Continued)

Field Description

ServerIronADX#rconsole 1 1ServerIronADX1/1 #show server hash vip108 Virtual port Hash Buckets: Virtual Server <vip108>, Virtual Port <80>:Bucket: Server Hit Bucket: Server Hit



Table 35 describes the information displayed by the show server hash command.

Example

Based on the following configuration, if an HTTP request has the lidl-shop-persist cookie which is a four-digit number, the number is hashed to match a real server that has already been hashed to the buckets (a total of 256).

csw-rule "persist-cookie" header "Cookie" search "lidl-shop-persist="csw-policy "test" match "persist-cookie" persist offset 0 length 4

server real rsXP 100.1.1.7port http port http group-id 1 10

server real rsXP1 100.1.1.71port http port http group-id 1 10

! server real rsXP2 100.1.1.72port http port http group-id 1 10

server virtual vip108 100.1.1.108port http port http csw-policy "test"port http csw port http keep-alivebind http rsXP http rsXP1 http rsXP2 http

In this example, four requests are sent that match the cookie, each with a different four-digit number. The cookie number of the first request is hashed and goes to real server rsXP in hash bucket 74, and its current bucket total hit number is 1, as displayed by the show server hash command.

TABLE 35 Output from the show server hash command

Field Description

Virtual Server The name of the virtual server.

Virtual Port The virtual port number.

Bucket The bucket number in which the real server is. The same real server can be in multiple buckets. There are a total 256 buckets.

Server The name of the real server.

Hit The number of requests that select the real server in this bucket.

ServerIronADX1/1 #sh server hash vip108 Virtual port Hash Buckets: Virtual Server <vip108>, Virtual Port <80>:Bucket: Server Hit Bucket: Server Hit 74: rsXP 1



The cookie number of the second request is hashed and goes to real server rsXP1 in hash bucket 243. Its current bucket total hit number is 1.

The cookie number of the third request is hashed and goes to real server rsXP1 in hash bucket 246. Its current bucket total hit number is 1.

The cookie number of the fourth request is hashed and goes to real server rsXP in hash bucket 32. Its current bucket total hit number is 1.

Displaying hash bucket countersThe hash bucket counters can provide useful information for tracing the reason why a persist based on a hash-to-bucket CSW policy failed during traffic flow. To display the hash bucket counters, use the show server proxy keep-alive command. The following truncated output displays the hash bucket counters:


ServerIronADX1/1 #sh server hash vip108 Virtual port Hash Buckets: Virtual Server <vip108>, Virtual Port <80>:Bucket: Server Hit Bucket: Server Hit 74: rsXP 1 243: rsXP1 1

ServerIronADX1/1 #sh server hash vip108 Virtual port Hash Buckets: Virtual Server <vip108>, Virtual Port <80>:Bucket: Server Hit Bucket: Server Hit 74: rsXP 1 243: rsXP1 1 246: rsXP2 1

ServerIronADX1/1 #sh server hash vip108 Virtual port Hash Buckets: Virtual Server <vip108>, Virtual Port <80>:Bucket: Server Hit Bucket: Server Hit 32: rsXP 1 74: rsXP 1

243: rsXP1 1 246: rsXP2 1

ServerIronADX#show server proxy keep-alive

Keep-alive connection statistics:...Hash Bucket Change:

Current serv is down = 1 Serv exceed max-con = 0Lower BP wins = 0

...


Usage guidelines5

Table 36 describes the hash bucket counter fields of show server proxy keep-alive command.

Usage guidelinesWhen you define an offset or negative offset value to insert or delete a string, the value is not allowed to go beyond the URL value defined by the associated CSW rule. If it does exceed the boundary of the URL value, the ServerIron adjusts it to align with the beginning or the end of the URL.

Similarly, the deletion action is not allowed to delete content beyond the URL value defined by its associated CSW rule. If the string to be deleted does exceed the start or end of the boundary of the URL or header value content, ServerIron limits the string to be deleted to the part within the boundary.

Syntax: match rule-name rewrite request-insert string [offset | neg-offset offset]

The rule-name variable defines the name of CSW rule.

The string variable defines the string to be inserted.

The offset variable defines the distance of bytes from the offset 0. By default, offset 0 is right after the interested string defined by matched CSW rule.

The offset or neg-offset keyword indicates that the insertion offset starting after or before the offset 0.

Support for large GET requestsThe ServerIron ADX can perform Layer 7 Content Switching on large GET requests (up to 20,000 bytes). Earlier releases supported up to 8,000-byte GET requests.

TCP/UDP content switchingThis section contains the following subsections:

• “Understanding TCP/UDP content switching” on page 359

• “Configuring TCP/UDP content switching” on page 359

• “TCP/UDP content switching commands” on page 363

TABLE 36 Output hash bucket counter fields of show server proxy keep-alive command

Field Description

Current serv is down The current server is down.

Serv exceed max-conn The number of times that the current server exceeds the max-conn configuration.

Lower BP wins The hash table is synchronized to all BPs. Where another BP assigns the bucket to a different server, the lower BP wins.


TCP/UDP content switching 5

Understanding TCP/UDP content switchingTCP/UDP content switching allows the ServerIron ADX to make switching decisions based on the content of TCP and UDP traffic. It allows you to make forwarding decisions by analyzing content anywhere within a TCP or UDP packet.

TCP/UDP content switching provides the following benefits:

• Extends the current prefix-suffix-pattern matching function to generic TCP and UDP content.

• Provides load balancing based on any content specified in the configuration.

• Adds multiple levels to the policy search function.

• Allows you to provide a sub-string for the next level of policy matching, depending on the policy matching result at the current level.

• Supports forwarding action, reset action (TCP only), and persisting request to server action.

• Supports content rewrite action, including insertion, deletion, and replacement.

• Supports pattern matching.

Specifications

TCP/UDP content switching has the following specifications:

• Cannot be used with legacy content switching. You must activate csw.

• Does not work with fragmented packets.

• No cookie insert, rewrite, or delete; no request or respond insert; no client-ip insert; no tcp off-load; no keepalive.

• No out of sequence packets.

• All content matches must be ASCII; no hex match are allowed.

Configuring TCP/UDP content switchingTo configure TCP/UDP content switching, you must first define TCP/UDP content switching rules and policies.

A rule specifies the content that the ServerIron ADX looks for in the incoming traffic. A policy associates rules with one or more actions that specify how the ServerIron ADX handles the traffic that matches the rules.

To enable TCP/UDP content switching, you must bind the policy to a virtual server.

The following required and optional tasks are used for configuring TCP/UDP content switching:

• “Define a TCP/UDP rule (required)”

• “Define a policy (required)”

• “Configure a forward action (required)”

• “Configure a persist action (optional)”

• “Configure a log action (optional)”

• “Configure a reset-client action (optional)”

• “Configure a rewrite action (optional)”


TCP/UDP content switching5

• “Configure a goto action (optional)”

• “Enable TCP/UDP content switching (required)”

Define a TCP/UDP rule (required)

A TCP/UDP rule causes a ServerIron ADX to make a load balancing decision based on the TCP/UDP content in an incoming packet, depending upon the port type. You can define up to 520 unique TCP or UDP rules.

Use the following procedure to configure a rule called rulea that matches any TCP packet with the string abcd between offset 10 and 40.

1. Enable privileged EXEC mode.

ServerIronADX> enable

2. Enable global configuration mode.

ServerIronADX#configure terminal

3. Configure a “tcp-content” rule and enter the csw-rule configuration mode.

ServerIronADX(config)#csw-rule rulea tcp-content pattern abcd case-insensitive

Syntax: [no] csw-rule rule-name tcp-content [ prefix | pattern ] string [case-insensitive]

This rule (rulea) specifies tcp-content of the pattern “abcd” and is case insensitive.

4. Set the parameter to specify the offset from where to begin scanning. depth specifies the depth of the content.

ServerIronADX(config-csw-rulea)#offset 10 depth 30

5. Return to global configuration mode.

ServerIronADX(config-csw-rulea)#exit

Define a policy (required)

A policy specifies the action to take when a rule is matched. Use the following procedure to create a TCP/UDP content switching policy.





3. Configure a policy name and enter the csw-policy configuration mode.

ServerIronADX(config)#csw-policy policy1 protocol anyServerIronADX(config-csw-policy1)#

Syntax: [no] csw-policy policy-name protocol any

After you create a policy-name, you can specify the following kinds of actions in a policy:

• Forward action

• Persist action

• Log action



• Reset-client

• Rewrite action

• Goto action

Configure a forward action (required)

A forward action causes a ServerIron ADX to forward packets that match a specified rule to a specified real server or server group.The following example specifies that packets matching rule rule1 be forwarded to real server 1029.

To configure a forward action for a TCP/UDP content switching policy, use the match forward command in the policy configuration mode.

ServerIronADX(config-tca-policy1)#match r1 forward 1029

Syntax: [no] match rule-name forward id

NOTEYou must have previously created a real-server and assigned server-id 1029 to it.

Configure a persist action (optional)

A persist action causes a ServerIron ADX to send requests with similar content to the same server when the specified rule is matched. When a rule is matched, the ServerIron ADX uses the content that matched the rule to select a server or server group to send the packet to.

To configure a persist action for a TCP/UDP content switching policy, use the match persist command in the policy configuration mode.

ServerIronADX(config-csw-policy1)#match rulea persist offset 10 length 10 hash-to-bucket

Syntax: [no] match rule-name persist offset offset-value [length length | terminator string] [hash-to-bucket]

The length variable specifies the length in bytes of the string to be hashed.

The offset-value variable specifies the start of the hash string.

NOTE If you specify 0 as the offset, the string starts at the beginning of the matched content.

Configure a log action (optional)

A log action causes the ServerIron ADX to write a message to Syslog when the specified rule is matched. You can optionally customize the format of the Syslog message.

To configure a log action for a TCP/UDP content switching policy, use the match log command in the policy configuration mode.

Syntax: [no] match rule-name log log_format

The following values can be used for the log_format variable:

• $SIP—Source IP

• $DIP—Destination IP



• $SPT—Source Port

• $DPT—Destination Port

• $RUL—Rule name

• $ACT—The action taken e.g forward

• $CNT—Content (The pattern that has been matched)

Example

ServerIronADX(config-csw-policy1)#match rulea log "source-ip = $SIP, dest-ip = $DIP, rule = $RUL matched"

NOTEThe log rule is a secondary rule that assumes an action rule is already specified. It only logs the action taken.

Configure a reset-client action (optional)

The reset-client action causes the ServerIron ADX to send a tcp reset to the client, which abruptly terminates the connection.

To configure a reset-client action for a TCP/UDP content switching policy, use the reset-client command in the policy configuration mode.

ServerIronADX(config-csw-policy1)#match rulea reset-client

Syntax: [no] match rule-name reset-client

Configure a rewrite action (optional)

The rewrite action causes the ServerIron to rewrite the matched string with a pattern that you specify. For instructions on how to use the rewrite action within a CSW policy, see the following sections:

• “Configuring Rewrite request-delete” on page 319

• “Configuring Rewrite request-insert” on page 324

Configure a goto action (optional)

The goto action causes the matched pattern to be forwarded to another policy as input and an evaluation to be performed. The goto action leads to another policy matching. The input string for the new policy matching is defined by the search result of the current policy matching result.

The matching starts from the first byte after the current policy matching result and goes to the end of the current policy input string.

The current matched rule must be a non-nested rule; otherwise, the goto action is not allowed.

To configure a goto action, use the match goto command in the policy configuration mode.

ServerIronADX(config-csw-policy1)#match r1 goto policy5

Syntax: [no] match rule-name goto policy-name



Define a nested rule (optional)

After you have defined the basic, standalone, rules, you can optionally bind them together to create more complex, nested, rules.

You can combine rules with logical operators to create nested rules. Up to four rules can be combined in a single nested rule. The following operators are supported.

The following procedure describes how to configure a nested rule.





3. Configure a nested rule name and a rule called nestedrule1 that combines three other rules: ruleA, ruleB, and ruleC.

ServerIronADX(config)#csw-rule nestedrule1 nested-content-rule ruleA

Syntax: [no] csw-rule rule-name nested-content-rule expression

NOTEThe nested rule is matched when an incoming packet matches ruleA, and either matches ruleB or does not match ruleC.

Enable TCP/UDP content switching (required)

To enable TCP/UDP content switching, you must first bind a TCP/UDP content switching policy to a virtual server. The following example shows how to enable TCP/UDP content switching on a virtual server called cswVIP:

ServerIronADX(config)#server virtual-name cswVIP 192.168.20.254ServerIronADX(config-vs-cswVIP)#port http csw-policy p1ServerIronADX(config-vs-cswVIP)#port http csw

Syntax: [no] server virtual-name virtual-name ip-address

Syntax: [no] port http csw-policy policy-name

Syntax: [no] port http csw

TCP/UDP content switching commandsThis section describes the syntax, semantics, and usage for each TCP/UDP content switching command. This section contains the following sections:

• csw-rule

• csw-policy

&& AND operator.

|| OR operator

! NOT operator.



• match

• begin-delimitor

• end-delimitor

• forward

• goto

• log

• persist

• reset-client

• rewrite

csw-rule

Use the csw-rule command in the global configuration mode to configure a content switching rule for TCP/UDP content switching.

Syntax: [no] csw-rule rule-name nested-content-rule expression | tcp-content [prefix | pattern] tcp-content| udp-content [prefix | pattern] udp-content| case-insensitive

Usage GuidelinesThe following options are available after you create a rule and enter the content switching rule configuration mode.

Command Modes• Global configuration mode.

• CSW configuration mode.

csw-rule Content switching rule command.

rule-name Specifies the name of the rule. Can be up to 80 characters in length.

nested-content-rule Specifies a nested content rule (compound rule).

expression Within the expression, you can include up to four rules, linked with logical operators. The following logical operators are supported:• && = AND• || = OR• ! = NOTA nested rule cannot be specified within the expression of another nested rule. The expression must refer to more one rule, unless the ! (logical NOT) operator is used.

tcp-content Specifies TCP content for load balancing.

tcp-content Specify content to be matched.

udp-content Specifies UDP content for load balancing.

udp-content Specify content to be matched.

case-insensitive Turns on the case-insensitive condition in the search.

offset offset depth depth Specify the offset from where to begin scanning depth specifies the depth of the content. max-offset can be 65535 max-depth can be 32768 (or 65535).



csw-policy

Use the csw-policy command in the global configuration mode to configure a content switching policy for TCP/UDP content switching.

Syntax: [no] csw-policy policy-name protocol any | case-insensitive

Usage GuidelinesAfter you create a policy and enter the TCP/UDP content switching policy-configuration mode, you must set a rule with the match sub-command.

match

Syntax: [no] match rule-name begin-delimitor | end-delimitor | forward ID| goto policy-name| log log_format| {persist offset value [length length | terminator string] [hash-to-bucket]} | reset-client | rewrite

csw-policy Content switching policy.

policy-name Policy name can be up to 80 characters in length.

protocol any protocol any must be entered or the legacy content switching policy is used.

case-insensitive Turns on the case-insensitive condition in the search.

match Specifies match sub-command.

rule-name Specifies the rule to be matched.

begin-delimitor Specifies to set this rule to be the beginning delimitor.

end-delimitor Specifies to set this rule to be the ending delimitor.

forward Specifies to forward the packets.

id Group ID is from 0 to 1023. Server ID is from 0 to 5119.

NOTE: The real server ID range is limited to 1024-1+the maximum number of real servers that can be configured on the ServerIron ADX model. For example, if the maximum server limit is 16384, then the valid real server ID range is from 1024 to 1024-1+16384=17407.

NOTE: Layer 4 Load Balancing takes place only if a valid server is not selected and a default csw-policy action is not configured.

goto Specifies to go to the next level.

policy-name Name of the policy.

log log_format The log_format can be a string that uses the following variables:• $SIP—Source IP• $DIP—Destination IP• $SPT—Source Port• $DPT—Destination Port• $RUL—Rule name• $ACT—The action taken e.g forward• $CNT—Content (The pattern has been matched)

persist Specifies the persist action for packets.

offset Specifies offset of content to hash.

offset-value Value for offset.


Miscellaneous Layer 7 switching configurations5

Miscellaneous Layer 7 switching configurations

Changing the maximum number of concurrent Layer 7 connectionsBy default, the ServerIron ADX allows a maximum of 100,000 concurrent Layer 7 switching connections.

To change the maximum number of concurrent Layer 7 switching connections from 100,000 to 160,000, enter a command such as the following.

ServerIronADX(config)#server max-l7-connections 160000

Syntax: [no] server max-l7-connections number

On ServerIron ADX Chassis devices, the number of concurrent Layer 7 switching connections can range from 100,000 to 512,000.

Dropping requests on exceeding max-conn per real server

Dropping the requests after exceeding the maximum number of connections

In an Layer 7 switching configuration, policies direct HTTP requests to real servers in load-balanced real server groups. When all the real servers in a server group have reached their maximum number of connections (by default, 1,000,000 connections or a threshold set with the max-conn command), HTTP requests that would normally go to the server group are instead sent to one of the other real servers bound to the VIP. The ServerIron ADX uses its load-balancing metric to select another real server to which it directs the request. If there are no other real servers bound to the VIP besides the ones in the server group, the request is dropped.

You can change the default behavior so that instead of being sent to a real server bound to the VIP, the requests are dropped. To do this, enter commands such as the following on each real server in the server group.

ServerIronADX(config)#server real-name server1 10.95.7.1ServerIronADX(config-rs-server1)#exceed-max-drop

length Specifies the length in bytes of the string to be hashed. If you specify 0 as the length, the string ends at the beginning of the matched content.

length Value for length.

terminator Specifies the terminator for the search string.

string Value of the terminator.

hash-to-bucket Specifies to persist by hashing.

reset-client Specifies to send a reset message to a client.

rewrite For instructions on how to use the rewrite action within a CSW policy, see the following sections:• “Configuring Rewrite request-delete” on page 319• “Configuring Rewrite request-insert” on page 324


Miscellaneous Layer 7 switching configurations 5

In this example, if Server1 reaches its maximum-connection threshold, and if all the real servers in the server group to which Server1 belongs also reach their maximum-connection thresholds, HTTP requests that would normally go to Server1’s server group are dropped.

Syntax: [no] exceed-max-drop

Dropping the requests when servers are unavailable

By default, if a policy is configured to direct an HTTP request to a server group, but none of the servers in that server group are available, the HTTP request is directed to one of the other server groups bound to the virtual servers service. You can change this default behavior so that the HTTP request is dropped rather than directed to another server group. To do this, enter the following commands.

ServerIronADX(config)#server virtual-name-or-ip vip1 192.168.1.234ServerIronADX(config-vs-vip1)#port http no-group-failover

Syntax: port http no-group-failover

Cleaning up all hash bucketsTo clean up all hash buckets when a server port comes alive, enter the following command.

ServerIronADX(config)#server l7-hashing-bucket-reassign

Syntax: [no] server l7-hashing-bucket-reassign

This command also allows new connections to be forwarded to the server port that has just come up.

Layer 7 content buffering optionsIn an Layer 7 switching configuration, the ServerIron ADX stores client request packets in the Layer 7 content buffer while it selects a real server to which to forward the request. The ServerIron ADX buffers the client request up to the end of the HTTP request, or up to a maximum of 20 packets.

The following two Content Buffering Options allow you to optimize the usage of the ServerIron ADX’s Layer 7 content buffer:

• Modifying the TCP window size so that the client sends fewer packets before waiting for an ACK

• Configuring the ServerIron ADX not to send an ACK to the client after it has received enough information to select a real server

Changing the TCP window size

The TCP window size in a SYN ACK or ACK packet specifies the amount of data that a client can send before it needs to receive an ACK from a server. By reducing the TCP window size for SYN ACK or ACK packets sent by the ServerIron ADX when performing Layer 7 switching, you can decrease the number of packets a client will send before it waits to receive an ACK from the ServerIron ADX, thus making more efficient use of the ServerIron ADX’s Layer 7 content buffer.

To change the TCP window size to 1460 bytes, enter the following command.

ServerIronADX(config)#server l7-tcp-window-size 1460

Syntax: server l7-tcp-window-size window-size



The default TCP window size is 8000 bytes. Setting the TCP window size to 1460 bytes causes a client to send only one packet before waiting for the ServerIron ADX to send an ACK, assuming a Maximum Segment Size (MSS) of 1460 bytes. This setting applies only to SYN ACK and ACK packets sent from the ServerIron ADX to the client. The ServerIron ADX does not modify the TCP window size for traffic sent from real servers to clients by way of the ServerIron ADX.

Preventing the ServerIron ADX from sending an ACK to the client

You can configure the ServerIron ADX not to send an ACK back to the client after the ServerIron ADX receives enough data from the client to select a real server. For example, if you enable this feature in a URL switching configuration, and the ServerIron ADX has received the entire URL in a request, it does not send an ACK to the client after receiving the last packet. Withholding the ACK prevents the client from sending further data to the ServerIron ADX, increasing the efficiency of the Layer 7 content buffer.

To cause the ServerIron ADX not to send an ACK to the client after it has received enough information to select a real server in a Layer 7 switching configuration, enter the following command.

ServerIronADX(config)#server l7-dont-ack-last-packet

Syntax: server l7-dont-ack-last-packet

HTTP 1.1 supportThe ServerIron ADX has HTTP 1.1 support for Layer 7 switching and the Server Connection Offload (HTTP Connection Proxy) features. These features help reduce TCP connection overhead by offloading the management of TCP connections from application servers and allowing them to dedicate resources for handling application transactions. These features significantly increase the performance and capacity of back-end servers, minimize the number of round trips between users and servers, reduce the bandwidth cost, and improve the Web experience of users.

HTTP was originally designed for simple text documents with embedded images that contain hyperlinks to other documents. For each hyperlinked image, HTTP 1.0, by default, creates a separate TCP connection, even if the images are all on the same server. In comparison, HTTP version 1.1 allows a TCP connection or keepalive connection to remain open until all consecutive requests and responses are complete. This technique is called persistent connection.

Persistent connection is enabled by default on HTTP 1.1 but is disabled by default in HTTP 1.0. For HTTP 1.0, Web browsers must explicitly insert the HTTP header "Connection: keepalive" to enable persistent or keepalive connections.

This release introduces two modes to support persistent connections: TCP offload mode and keepalive mode. Both modes try to maintain and reuse keepalive connections on both the client side and the server side.

TCP offload mode allows a request from one connection on the client side to re-use any established connection on the server side. TCP offload mode offloads the management of TCP connections from servers so they can dedicate resources to serving HTTP requests instead of managing connections.

The re-use of open connections causes the source IP address and port of the request to be translated from the original connection on the client side to a connection on the server side. Consequently, a server cannot distinguish between clients simply by the source IP address of the connections. If servers need to distinguish between clients’ source IP addresses, the keepalive mode is recommended. It reuses the connections on the server side for application requests from



clients that originally created the connections. When a client makes a request for content that is served by a different server, the ServerIron ADX switch closes the connection to the original server on the server side before setting up a connection with the new server; however, the connection on the client side can still be reused if keepalive mode is enabled on the client connections.

Default settings

By default, HTTP 1.0 is the version of HTTP that comes enabled on ServerIron ADXs for any Layer 7 switching feature. However, HTTP 1.0 connections are non-persistent, and therefore persistent connections or keepalive connections are disabled by default. To support persistent connections, enable TCP connection offload mode or keepalive mode on a virtual port. These modes are enabled at the virtual server level.

Enabling the TCP offload mode

TCP offload mode allows a request from one connection on the client side to reuse any established connection on the server side.

To enable persistent connection in TCP offload mode for the HTTP port on a virtual server named "vserv1", enter the commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip vserv1ServerIronADX(config-vs-vserv1)#port http tcp-offload

Syntax: [no] port port tcp-offload [age minutes]

or

Syntax: [no] port port tcp-offload [transactions trans-num]

The age minutes variable specifies how many minutes a connection on the server side can be kept alive. If it is not specified, by default, the keepalive time will be the same as the session age, which can be defined globally by entering the command server tcp-age minutes or locally under the virtual server level by entering the command port port-num tcp-age minutes.

The transactions trans-num variable specifies the maximum number of HTTP transactions that can be completed on a connection on the server side.

If the age or transaction limit is reached, the connection on the server side is closed and a reset packet will be sent to the server.



Graceful handling of HTTP pipelined requests

If either HTTP, SSL terminate, or SSL Proxy is enabled, a client supporting persistent connection can use pipelining by allowing multiple requests to be sent over the same connection without waiting for a response for each request. (Refer to the Secure Socket Layer (SSL) Acceleration chapter of the ServerIron TrafficWorks Security Guide for details on SSL terminate and SSL Proxy.) Before software release 11.0.00, ServerIronADX did not support pipelining because most web browsers have this feature disabled by default. However, if the Web browser supports pipelining and Layer 7 switching is enabled on the ServerIronADX, then ServerIronADX does the following:

• If the pipelined HTTP requests are within the same packet, ServerIronADX will make the switching decision based on the first request and direct all the subsequent pipelined requests to the same server to which the first request was directed. Pipelining will disable Layer 7 switching on subsequent requests.

• If a client sends pipelined HTTP requests in separate packets before the ServerIronADX can send a response for the first request, ServerIronADX makes Layer 7 switching decisions based on the first request. All subsequent pipelined requests will be dropped until the response for the first request is successfully received by the client. This scenario can cause degradation, resulting in poor end-user experience.

• If the tcp-offload or keepalive option is enabled under the virtual server port, when a reply comes back from a real server in response to the pipelined request, the ServerIron drops this reply; therefore, the end-client does not receive the response.

Beginning with release 11.0.00, ServerIron can be configured to handle the first request of a pipelined request correctly and optionally send reset to the subsequent requests. This feature helps prevent performance degradation. Reset can be enabled in keepalive mode or TCP offload mode.

This feature works only when Content Switching is enabled on a virtual server port. if pipelined HTTP requests are sent in one connection, the ServerIronADX makes the switching decision based on the first request and forwards only the first request to the real server. When the real server sends a complete response to the first request, the ServerIronADX will forward the response to the client. After the client acknowledges the complete response, one of the following occurs:

• For HTTP traffic, the ServerIronADX closes the connection by sending a RST to the client.

• For SSL-terminate or SSL-proxy, the ServerIronADX closes the connection by sending a FIN to the client.

NOTEResetting the HTTP connection can be done in either the keepalive mode or the TCP offload mode.

To reset a pipelined HTTP request in the keepalive mode, first make sure Content Switching is enabled on a virtual server port that will be used for the pipeline reset request.

Then, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip VS1 10.10.10.10ServerIronADX(config-vs-VS1)#port httpServerIronADX(config-vs-VS1)#port http keep-alive reset-pipeline-request

Syntax: [no] port [portid] keep-alive [reset-pipeline-request]



To reset pipelined HTTP request in the TCP offload mode, enter commands such as the following.

ServerIronADX(config)#server virtual-name-or-ip VS1 10.10.10.10ServerIronADX(config-vs-VS1)#port httpServerIronADX(config-vs-VS1)#port http tcp-offload reset-pipeline-request

Syntax: [no] port port tcp-offload [age minutes] [reset-pipeline-request]

or

Syntax: [no] port port tcp-offload [reset-pipeline-request]

Clearing all keepalive connections

To delete all keepalive server side connections on all the applicable virtual servers, enter the following command on the ServerIron ADX.

ServerIronADX#clear server keep-alive virtual

Syntax: [no] clear server keep-alive [virtual | real] [server-name] [port]

Enter the virtual option if you want to delete all the keepalive connections associated with the virtual server, or the real option if they are to be deleted from the specified real server.

The optional server-name and port variables specify the name or port of the virtual or real server from where you want to delete the keepalive server-side connections. When you enter this command, all the keepalive connections will be removed from the reuse pool. The ServerIron ADX sends reset packets to the real or virtual servers to close any open connections.

Displaying transactions and connections

To display information about the transactions and connections for Layer 7 switching over keepalive connections, enter the following command.

ServerIronADX4/1#show server session keep-alive

Avail. Sessions = 1999972 Total Sessions = 2000000Hash size = 200001

Total C->S Conn = 0 Total S->C Conn = 0Total Reassign = 0 Unsuccessful Conn = 0Server State - 1:enabled, 2:failed, 3:test, 4:suspect, 5:grace_dn, 6:active

Real Server St CltConn:Cur/Tot SerConn:Cur/Tot CurrTrans IdleSerCon TotTransMyServer01 1 11/46 3/5 2 1 147MyServer02 1 0/0 0/0 0 0 0MyServer03 1 0/0 0/0 0 0 0



Table 37 specifies the show server session keep-alive command fields and its description.

In the example above, MyServer01 on WSM CPU ServerIron4/1 has 11 concurrent client-side connections and 3 concurrent server-side connections to the Real Server MyServer01. Two of the 3 server-side connections are processing different HTTP transactions and the third one is idle.

In addition, clients made a total of 46 connections to the ServerIron; while the ServerIron only needs to create a total of 5 server-side reusable keep-alive connections to MyServer01 to serve all the requests sent on the 46 client-side connections. In those 46 client-side connections and 5 server-side connections, 147 HTTP transactions have been completed.

Syntax: show server session keep-alive

NOTEThis command only works on the ServerIron ADX.

Layer 7 CSW pseudo stack client-side retransmission handlingThe ServerIron ADX Content Switching (CSW) pseudo stack needs to store HTTP request packets from the client before it is able to perform server selection. If the stored packets are not acknowledged by the CSW pseudo stack and these packets get dropped before reaching the server, they can be retransmitted by the client. However, there are cases when the ServerIron ADX needs to acknowledge those stored packets before forwarding them to the server. An example of this is when the client’s HTTP request spans multiple packets, and the client expect an acknowledgment before transmitting the remaining request packets. Upon receiving all request packets, the ServerIron ADX performs server selection and transmits all requests packets to the server. Since the current CSW pseudo stack does not keep the stored packets once they are sent out, they will never be transmitted if these packets get dropped. If this occurs, the client will keep retransmitting the request for acknowledgement to the ServerIron ADX, until the TCP timeout expires. As a result, the client will notice that the HTTP transaction never gets completed.This issue becomes more relevant when the ServerIron ADX Layer 7 Transparent Cache Switching (TCS) feature bypasses HTTP traffic to the Internet server over an unrealiable WAN link.

TABLE 37 Fields in the show server session keep-alive display

Field Description

CltConn:Cur/Tot: Number of current and total client-side connections on this BP.

SerConn:Cur/Tot: Number of current and total server-side connections on this BP. When persistent connection is enabled, the number of current and total server-side connections is typically much less than the current and total client-side connections, because a server-side connection can be reused by requests from any client-side connection.

CurrTrans: Number of busy server side connections that are in the process of serving HTTP transactions. The difference between number of current client-side connections and CurrTrans indicates the number of current idle client-side connections.

IdleSerCon: Number of idle server-side connections that are available to be re-used by new requests made to the same server. The sum of CurrTrans and IdleSerCon is equal to the number of current server-side connections.

TotTrans TotTrans: Total number of HTTP transactions that have been successfully completed for the server. Because a persistent connection allows multiple HTTP transactions to be done, TotTrans typically have a much higher value than the total number of both client-side and server-side connections.



Starting with software release 12.4.00c, the ServerIron ADX supports handling of HTTP request retransmission with Layer 7 pseudo stack. When the Layer 7 CSW pseudo stack retransmission handling is enabled, the ServerIron ADX acknowledges and stores the client TCP packets, and does not clear its buffer until the request packets are acknowledged by the server. If the retransmission timer triggers befor the request packets are acknowledged, the ServerIron ADX will resend th stored packets.

The Layer 7 CSW pseudo stack retransmission handling feature is disabled by default.

Enabling the Layer 7 CSW client-side retransmission handling

To enable Layer 7 CSW pseudo stack retransmission handling feature, enter the command as follows:

ServerIronADX(config)#server csw enable-retransmission

Syntax: [no] server csw enable-retransmission

Displaying the Layer 7 CSW client-side retransmission handling information

In order to display information about Layer 7 CSW client-side retransmission handled by the ServerIron ADX, use the show server proxy keep-alive command. A truncated display is shown:


This command displays the HTTP keep-alive connection statistics and also includes the retransmission counters.

ServerIronADX 1000#show server proxy keep-alive

Keep-alive connection statistics:...

Client-side statistics: In seq. packets = 412 Unexpected data = 0

Out of seq. packets: Syn_recv = 0 Wait_req state = 0 Not_complete = 0 Req_sent state = 0 Reply_sent = 0 = 0

Retransmit packets: Syn_sent = 0 Req_sent state = 0 Reply_sent = 0 Req_sent state(old) = 0 Reset cast to ack = 0 Fin cast to ack = 0 Ack cast to Reset = 0 Dup rev in Syn_sent = 0 Dup rev in src nat = 0 = 0

Reset packets received: Syn_recv = 6 Wait_req = 0 Syn_sent = 0 Req_sent = 0 Rep_sent = 0 Page_replied = 0 Unknown = 0 Others = 0...Hash Bucket Change: Current serv is down = 0 Serv exceed max-conn = 0 Lower BP wins = 0 = 0...ServerIronADX 1000#



NOTEThe Layer 7 CSW pseudo stack retransmission handling feature does not support High Availability (HA). If HA is configured for active symmetric mode and this feature is enabled, the ServerIron ADX that is receiving the client request will send and free the stored packets and will not do retransmission handling.

NOTEThe Layer 7 CSW pseudo stack retransmission handling feature supports IPv6.

Layer 7 CSW pseudo stack server-side TCP packet out-of-sequence handlingWith the current Layer 7 Content Switching (CSW) pseudo stack, the ServerIron ADX expects all TCP packets from the server-side to arrive in-sequence. If the server-side TCP packets are received out-of-sequence, the ServerIronADX will silently drop the out-of-sequence TCP packets and then wait for either the TCP stack timeout to expire, or for the server to retransmit. If this occurs, the end-user will experience slowness while browsing certain Web pages over the Internet.

This issue becomes especially evident when the ServerIron ADX Layer 7 Transparent Cache Switching (TCS) feature bypasses HTTP traffic to the Internet server over a slow WAN link. Starting with release 12.4.00c, the ServerIron ADX Layer 7 CSW pseudo stack will support handling of packet-drops and out-of-sequence TCP packets arriving from server-side as well.

NOTEThe Layer 7 CSW pseudo stack TCP packet out-of-sequence handling feature supports IPv6.



Displaying server-side link connections

In order to display information about the server-side out-of-sequence TCP packets handled by the ServerIron ADX, use the show server proxy keep-alive command. The statistics relevant to the out-of-sequence TCP packets are shown (in bold) in the following abbreviated output and described in Table 38.


NOTEThis command is available at the ServerIron ADX BP console only.

The fields described in Table 38 provide statistics about out-of-sequence (oos) TCP packets.

TABLE 38 Out-of-sequence TCP packets statistics

Field Description

Total stored oos pkt The total number of out-of-sequence packets buffered by the ServerIron ADX.

Total freed oos pkt The total number of out-of-sequence packets transmitted by the ServerIron ADX.

ServerIronADX 1000#show server proxy keep-aliveKeep-alive connection statistics:

Server-side statistics:... TCB status: Total in mem = 512000 Current in pool = 0 Allocated from mem = 301 Freed to mem = 300 Allocated from pool = 0 Freed to pool = 0 ... Connection unreusable reasons: Small window = 0 No rev sess = 0 Not reusable = 0 Fin/RST received = 0 Image = 0 = 0

Delayed ACK list status: Total TCBs in list = 12 Curr TCBs in list = 0 Generated ack num = 0

Out of sequence packet buffering: total stored oos pkt = 3 total freed oos pkt = 3 total timeout drop = 0 total oversize drop = 0 ... SYN_RECV = 0 WAIT_REQ = 0 NOT_COMPLETE = 0 REQ_STORED = 0 SYN_SENT = 0 REQ_SENT = 0 PAGE_REPLIED = 0 STATE_UNKNOWN = 0...KA DEBUG: URL_MULTI_STATE_FREED [ 31] = 113...

ServerIronADX 1000#


Setting up SSL session ID switching5

Setting up SSL session ID switchingSSL (Secure Sockets Layer) is a protocol for secure World Wide Web connections. The SSL protocol protects your confidential information with server authentication, data encryption, and message integrity. SSL is layered beneath application protocols such as HTTP, Telnet, FTP, Gopher, and NNTP, and layered above the TCP/IP connection protocol. This structure allows SSL to operate independently of the Internet application protocols. With SSL implemented on both the client and server, your Internet communications are transmitted in encrypted form, ensuring privacy.

For SSL to work, all the SSL connections between a client and server must reach the same host. SSL connections come in sequentially on particular ports; only one is open at a time. However, each must go to the same server.

SSL Session ID switching is the ServerIron ADX’s ability to connect a client to the same real server to which it had previously established an SSL (Secure Sockets Layer) connection.

SSL provides security in Web transactions. An SSL connection is initiated when a user clicks a hyperlink that begins with "https" (for example, https://secure.brocadenet.com). The browser (client) initiates an SSL connection with the server on TCP port 443, a secure link is negotiated, and encrypted data is transferred across it.

The SSL Handshake Protocol (SSLHP), one of two component protocols of SSL, negotiates the connection between the client and server. SSLHP establishes security parameters for an SSL session, including the SSL version number and the method of data encryption to use. One of the security parameters set by SSLHP is the SSL Session ID, a variable-length value contained in the session_id field in SSLHP messages. The SSL Session ID indicates whether the client wants to use the security parameters established in a previous session or establish a completely new connection.

To set up SSL session ID switching, perform the following tasks:

1. Configure the real servers for SSL.

2. Configure the virtual server for SSL session ID switching.

3. Adjust the age timer in the ServerIron ADX’s database (optional).

4. Adjust the maximum number of session_id-to-real-server associations that the ServerIron ADX can store in its internal database (optional).


Setting up SSL session ID switching 5


Figure 35 illustrates how the initial SSLHP messages exchanged between a client and server, client_hello and server_hello, establish an SSL Session ID.

FIGURE 35 How the SSL Handshake Protocol Establishes a Session ID

If the value in the session_id field that the client sends to the server is non-zero, the ServerIron ADX can connect the client to the server that originally sent the Session ID value. Figure 36 illustrates how this function, called SSL Session ID switching, works.

NOTESSL Session ID switching is supported for SSL v3.0 and higher only. In SSL versions prior to 3.0, the session ID was established later in the handshaking process, after the client and server had started exchanging encrypted data. If the session ID is encrypted, the ServerIron ADX cannot make forwarding decisions based on this information.

If the client source IP address is changed, session persistence based on SSL Session ID does not work since Session ID information is not copied across Application Processors. If the source IP is changed, the session may be processed by different Application Processor. The only exception is SI-1008-1 model with single Application Processor.


Setting up SSL session ID switching5

FIGURE 36 How the ServerIron ADX uses an SSL Session ID to Select a Real Server

Figure 36 illustrates the following process.

1. The first time a client attempts to establish an SSL connection to the server, there is no history of a previous SSL session, so the session_id field in the client_hello message it sends to the server is empty.

2. The server (in this example, real server rs10) sees that the session_id field in the client_hello message is empty, indicating the client wants to establish a new SSL session. The server responds to the client with a server_hello message that contains a session_id field with a non-zero value.

3. The ServerIron ADX examines the value in the session_id field sent by the server. The ServerIron ADX adds this value to an internal database, associating it with the real server that sent it. This association between the session_id value and the real server resides in the ServerIron ADX’s database for a user-specified amount of time (default 30 minutes), after which it is aged out. In this example, the ServerIron ADX would map the value in the session_id field to real server rs10.

4. When the client resumes the SSL connection to the server, it sends a client_hello message containing the session_id value sent by the server.

5. The ServerIron ADX examines the value in the session_id field sent by the client and looks it up in its internal database.

6. If the value in the session_id field maps to a real server, the ServerIron ADX initiates a TCP connection to the server and passes the client_hello message to it. The ServerIron ADX forwards subsequent packets between the client and server with modifications to the IP and TCP header for sequence number, acknowledgment number, and checksum adjustment.

Configuring the real servers for SSL

To configure the real servers for SSL shown in Figure 36, enter commands such as the following.

ServerIronADX(config)#server real-name rs10 10.157.22.10ServerIronADX(config-rs-rs10)#port sslServerIronADX(config-rs-rs10)#exitServerIronADX(config)#server real-name rs20 10.157.22.20ServerIronADX(config-rs-rs20)#port sslServerIronADX(config-rs-rs20)#exit

Syntax: server real-name real-server-name ip-addr


Setting up SSL session ID switching 5

Syntax: port ssl

The server real-name command defines the names and IP addresses of the real servers.

The port ssl command adds port 443 (SSL) to the real servers.

Configuring the virtual server for SSL session ID switching

The following commands enable SSL Session ID switching on a virtual server called sslVIP.

ServerIronADX(config)#server virtual-name-or-ip sslVIP 10.157.22.241ServerIronADX(config-vs-sslVIP)#port ssl session-id-switchingServerIronADX(config-vs-sslVIP)#bind ssl rs10 sslServerIronADX(config-vs-sslVIP)#bind ssl rs20 ssl

Syntax: port ssl session-id-switching

Syntax: port port-number session-id-switching

Syntax: bind ssl real-server-name ssl

The port ssl session-id-switching command enables SSL Session ID switching on this virtual server.

The bind ssl ssl command binds the virtual server to SSL services on the real servers. In this example, the commands associate real servers rs10 and rs20 with the virtual server.

NOTEFor clarity, the bindings in the example are shown as two separate entries. Alternatively, you can enter all the binding information as one command: for example, bind ssl rs10 ssl rs20 ssl.

Adjusting the age timer

By default, the ServerIron ADX keeps the entry associating a session_id with a real server in its database for 30 minutes. After 30 minutes, the entry ages out of the database. You can change the length of time the ServerIron ADX keeps the entry in the database,

To change the aging period from its default of 30 minutes to 10 minutes, enter a command such as the following.

ServerIronADX(config)#server session-id-age 10

Syntax: [no] server session-id-age minutes

The minutes variable is defined in minutes within the range from 2 through 60.

Adjusting the maximum number of session_id-to-real-server associations

By default, the ServerIron ADX can store in its database 8,192 entries associating a session_id with a real server.

You can change the maximum number of database entries to any larger value up to 256,000 by entering a command such as the following.

ServerIronADX(config)#server max-ssl-session-id 256000

Syntax: server max-ssl-session-id number

The number variable specifies the number of database entries. This variable can range from 8,192 through 256,000.


Command reference5

Command referenceThis section describes the following HTTP URL Rewrite options. These "options" are part of the match command.

• “rewrite request-delete”

• “rewrite request-insert”

• “rewrite request-replace”

rewrite request-deleteUse the rewrite request-delete option in the CSW policy configuration mode to delete content, as shown in the following.

ServerIronADX(config-csw-mypolicy)#match r11 rewrite request-delete offset 4 2

Syntax: match rule-name rewrite request-delete {matched-string | neg-offset offset length | offset offset length | string ASCII string}

The matched-string parameter specifies the matched-string option for the request to delete a string defined by a rule.

The neg-offset parameter specifies the negative-offset option for the delete request as defined by the following variables:

• The offset variable is the value of the deletion offset.

• The length variable is the value of the length of content to be deleted.

The offset parameter specifies the positive-offset option for the delete request as defined by the following variables:

• The offset variable is the value of the deletion offset.

• The length variable is the value of the length of content to be deleted.

The string parameter specifies the string option for the delete request as specified by the following variable:

The ASCII-string variable specifies the value of the string to be deleted.

rewrite request-insert Use the rewrite request-insert option in the CSW policy configuration mode to insert content, as shown in the following.

ServerIronADX(config-csw-mypolicy)#match r11 rewrite request-insert abc offset 4

Syntax: match rule-name rewrite request-insert {[ASCII-string [neg-offset decimal | offset decimal]] | client-ip | header}

The ASCII-string variable specifies the value of the string for the offset options, listed below, in the insert request.

The neg-offset parameter specifies the negative offset option for the insert request as the value specified in the decimal variable.

The offset parameter specifies the positive offset option for the insert request as the value specified in the decimal variable.


Command reference 5

The client-ip parameter specifies the client IP option for the insert request.

NOTEThe value of the client-ip must be defined under the VIP command.

The header parameter specifies the header option for the insert request.

NOTEThe value of the header must be defined under the VIP command.

rewrite request-replace Use this option in the CSW policy configuration mode to replace content, as shown in the following.

ServerIronADX(config-csw-mypolicy)#match r11 rewrite request-replace matched-string

Syntax: match rule-name rewrite request-replace {matched-string ASCII string | string ASCIIstring-old ASCIIstring-new}

The matched-string parameter specifies the matched-string option for the request to replace a string defined by a rule that is specified by the ASCII string variable.

The string parameter specifies that a string defined by the ASCIIstring-old variable must be replaced by a string of the ASCIIstring-new variable.


Command reference5



Chapter

6
High Availability
IntroductionThis chapter describes the high availability feature in ServerIron.

NOTEIn high availability configurations, with Brocade hardware-based SSL acceleration in either SSL Termination or SSL Proxy mode, synchronization of proxied or terminated SSL sessions is not supported.

High availability (HA) for server load balancing (SLB) consists of three ServerIron ADX services: Hot Standby HA, Symmetric Active-Standby HA, and Symmetric Active-Active HA.

Hot Standby HAOne ServerIron ADX is always active while the other ServerIron ADX is always standby. Hot Standby is supported on both stackable and chassis systems. On chassis systems, Hot Standby is supported only in Switch (S) code, not Router (R) code. Refer to “Hot Standby HA” on page 384.

Symmetric Active-Standby HABoth ServerIron ADXs can receive SLB traffic, but only the active VIP handles the L4-7 SLB, while the standby VIP functions as a standby. The VIP with the highest configured sym-priority handles the flow. Symmetric Active-Standby HA is supported in both Switch (S) code and Router (R) code. Refer to “Symmetric Active-Standby HA” on page 399.

Symmetric Active-Active HAActive-active is also called as true active-active. Both ServerIron ADXs can receive SLB traffic, and both are active for the same VIP. Configuring Symmetric Active-Active HA and sym-priority on the VIP enables a device to process traffic. Refer to “Symmetric Active-Active HA” on page 416.

With Direct Server Return (DSR), return traffic is not processed by the ServerIron ADX. Instead, the real server sends return traffic directly to the client. You can apply DSR to each of the HA scenarios (Hot Standby HA, Symmetric Active-Standby HA, and Symmetric Active-Active HA).

NOTEWhen a device is active, it responds to Address resolution Protocols (ARP) and processes all traffic for the VIP. When a device is acting as standby, it performs no processing functions for the specified VIP (other than session syncing with the active device, if enabled).

383

Hot Standby HA6

Hot Standby HABecause Hot Standby HA is an HA feature, there must be two ServerIron ADXs in the network. If only one device is present and the Hot Standby HA feature is enabled, the ServerIron ADX will function in "single-box" mode until the second ServerIron ADX becomes available.

There are two versions of Hot Standby HA:

• Standard Hot Standby HA - The ServerIron ADX’s management IP, VIPs, and real servers are all in the same subnet.

• Source-IP/src-standby-ip Hot Standby HA - The ServerIron ADX’s management IP and VIPs are in one subnet. Real servers are in a different subnet. Additional commands are required for this version.

For Hot standby HA, one ServerIron ADX is always active while the other ServerIron ADX is always standby (idle).

Hot Standby HA allows you to configure two ServerIron ADXs to serve as a redundant pair (primary and secondary). If the active ServerIron ADX fails, the idle standby ServerIron ADX assumes the active duties and becomes the new active device.

Hot Standby HA is the only HA service counting the number of available router-ports and server ports for failover behavior. The ServerIron ADX with the highest number of active ports is declared the active device. In addition to port-count loss, a system reload or crash triggers a failover.

Hot Standby HA protocol operationsFigure 37 illustrates a typical Hot Standby HA configuration.

FIGURE 37 Typical Hot Standby HA


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When ServerIron ADX A comes up in a Hot Standby HA configuration, it comes up in standby state. When it sends Hello messages and sees that no other ServerIron ADX is responding to those Hello messages, ServerIron ADX A assumes the active state. When ServerIron ADX-B comes up, it also goes through Hello-message processing. When ServerIron ADX B sends Hello messages, ServerIron ADX A responds to ServerIron ADX B with ServerIron ADX A's Active Status. ServerIron ADX B assumes Standby status. ServerIron ADX A in the active state performs the following four stages of synchronization:

• Port map synchronization

• MAC table synchronization

• Server information synchronization

• Session synchronization

When the entire synchronization process is complete, ServerIron ADX B calculates to see if ServerIron ADX A has a higher router-port plus server-port count or if ServerIron ADX B has the higher count. If the count is equal for both ServerIron ADX A and ServerIron ADX B, then ServerIron ADX B continues in the standby state. If ServerIron ADX A has a lesser count of router-port plus server-port, ServerIron ADX B forces ServerIron ADX A to go to standby state, and ServerIron ADX B assumes the active state. From this point on, ServerIron ADX A will be in the active state and ServerIron ADX B will be in the standby state until some event forces a change in their status. Events leading to change can include:

• An increase or decrease in the count of router-port plus server-ports

• Failure of one BP forcing all BPs to fail

• A reload

While standby ServerIron ADX B is idle, it continuously listens to Active ServerIron ADX A for fail-over preparation. ServerIron ADX A synchronizes its session table on the BPs to match the BPs on Standby ServerIron ADX B. This action occurs the moment a session is created on Active ServerIron ADX A. Synchronization of a session involves session creation, session deletion, and age updates. No CLI commands are required to invoke session synchronization from Active ServerIron ADX A to Standby ServerIron ADX B. ServerIron ADX A and ServerIron ADX B perform Layer 2, Layer 3, Layer 4, and Layer 7 health checks independently. To avoid a loop, ServerIron ADX B becomes a dumb device in Standby. All it does is receive session-sync messages from Active, perform health checks, and process Hello messages. ServerIron ADX B is completely isolated and does not process any SLB traffic. If ServerIron ADX A fails, ServerIron ADX B becomes Active and immediately takes over the processing of SLB traffic. Because the sessions were already synchronized from ServerIron ADX A when it was Active, failover is transparent to users.

Despite the stability of this solution, having an inactive device (ServerIron ADX B) with all its VIPs in standby state can be viewed as a limitation. For this reason, Brocade created a new HA feature called Symmetric Active-Standby HA (refer to “Symmetric Active-Standby HA” on page 399).


Hot Standby HA6

Configuring Standard Hot Standby HAFigure 38 shows the minimum required configuration for Standard Hot Standby HA.

FIGURE 38 Minimum required configuration for Standard Hot Standby HA

Follow these steps to enable the minimum required configuration shown in Figure 38. Client connections and server connections must be on the same interfaces on both ServerIron ADXs.

1. On ServerIron ADX A, place the untagged Hot Standby HA port (sync-link) in its own port-specific VLAN and disable STP:

ServerIronADX-A(config)#vlan 2 by portServerIronADX-A(config-vlan-2)#untagged ethe 2/1ServerIronADX-A(config-vlan-2)#no spanning-tree

Placing the Hot Standby HA port in its own VLAN prevents unnecessary traffic from going over the backup (sync) link. Note that the backup link does not have to be directly connected. There could be a layer 2 switch between two ServerIron ADX application switches in the HA pair as long as the latency is reasonably low, e.g, under 10ms and packets are delivered reliably between the ServerIron ADX application switches.

2. To avoid system conflicts, globally disable spanning-tree on VLAN 1:

ServerIronADX-A(config)#vlan 1 name DEFAULT-VLAN by portServerIronADX-A(config-vlan-1)#no spanning-tree


Hot Standby HA 6

3. Configure the server backup port, shared chassis-MAC address between the ServerIron ADXs, and any connected router-ports:

The server backup ethernet command must be configured exactly the same on both ServerIron ADXs. It has three parameters.

Syntax: server backup ethernet portnum mac-addr vlan-id

The portnum variable specifies the port where the syn-link is connected. This port connects this ServerIron ADX switch to its counterpart. In the example, 2/1 is the port number.

The mac-addr variable specifies the chassis-MAC address of one of the ServerIron ADXs. Be sure to use a chassis MAC from one of the two devices, not the MAC of one of the backup ports. Use the show chassis command to locate the chassis MAC. If both devices already have the same chassis MAC (because of a manufacturing error), then one of them must change.

The vlan-id variable specifies a VLAN that you want to use for Symmetric Active-Standby HA synchronization traffic. In this example, the sync-link Hot Standby HA port is in VLAN 2.

The server router-ports command enables the ServerIron ADX to count the number of upstream (or downstream) router ports connected to the switch. Both ServerIron ADXs must use the same router-ports numbers, such as 2/3 in this example. The reason is the standby ServerIron ADX is a dummy device that learns nothing, such as MACs, on its own.

4. Save the configuration.

ServerIronADX-SLB-A #wr mem.Write startup-config in progress..Write startup-config done.ServerIronADX-SLB-A#reload

NOTEBe sure to reload the software after configuring or changing the server backup port number or MAC address. If you change the port number of the backup while the ServerIron ADX is load balancing, clients will not be able to ping the VIP.


Hot Standby HA6

5. Configure the second ServerIron ADX (ServerIron ADX-B). On this system, port 2/1 is the Hot Standby HA port. Using the same port numbers and MAC address is a requirement. Notice the chassis-MAC address on each ServerIron ADX matches.

ServerIronADX-B#server backup ethe 2/1 00e0.5201.0c72 vlan-id 2ServerIronADX-B#server router-ports ethernet 2/3ServerIronADX-B#server router-ports ethernet 2/4

ServerIronADX-B(config)#vlan 1 name DEFAULT-VLAN by portServerIronADX-B(config-vlan-1)#no spanning-tree

ServerIronADX-B(config-vlan-1)#vlan 2 by portServerIronADX-B(config-vlan-2)#untagged ethe 2/1ServerIronADX-B(config-vlan-2)#no spanning-tree

ServerIronADX-B#write memory.Write startup-config in progress..Write startup-config done.ServerIron ADX-B#reload

NOTEIf you plan to configure real servers to use a source IP address configured on the ServerIron ADX as a default gateway, use the source-standby-address or source-nat-address command rather than the source-ip or source-nat command.

6. Use the show server backup and show log commands to obtain a clear picture of the ServerIron ADX’s status in the Hot Standby HA configuration.

The following screen shots display the different stages of reload and show how a ServerIron ADX comes up in a Hot Standby HA configuration.


Hot Standby HA 6

ServerIron ADX A is running in single-box mode, because ServerIron ADX B is not yet discovered.

Now ServerIron ADX B comes up. ServerIron ADX A is already up and running.


Hot Standby HA6

.Table 39 describes the information displayed by the show server backup command.

TABLE 39 Field descriptions for show server backup command

Field Description

Switch state Indicates whether this ServerIron ADX is the active ServerIron ADX or the standby. The state can be one of the following:• Active• Standby

SLB state When a ServerIron ADX comes up in the Hot Standby HA configuration (supported using switch images only), it requests the following information from the peer ServerIron ADX:• Port map information• MAC information• Server mapping information• Session information (Fail-over session sync)After this processing is completed, the ServerIron ADX goes to the "SLB synchronization complete" state.The "SLB State" field in the show server backup command denotes which of the above states the ServerIron ADX is in:• SLB_SYNC_COMPLETE state (Value = 0). All synchronization requests from the local

ServerIron ADX have been sent to the peer ServerIron ADX. This process is now complete (value = 0).

• SLB_SYNC_REQ_MAP state (Value = 1). Denotes the local ServerIron ADX is requesting the peer ServerIron ADX for port map information.

• SLB_SYNC_REQ_MAC state (Value = 2). Denotes the local ServerIron ADX is requesting the peer ServerIron ADX for MAC information.

• SLB_SYNC_REQ_SERVERS state (Value = 3). Denotes the local ServerIron ADX is requesting the peer ServerIron ADX for Server mapping.

• SLB_SYNC_REQ_L4 state (Value = 4). Denotes the local ServerIron ADX is requesting the peer ServerIron ADX for session synchronization (fail-over session sync).

SLB Partner MAC valid

Indicates whether the SLB partner MAC address listed in the SLB Partner MAC field is valid. The value can be one of the following:• 0 – invalid• 1 – valid

SLB Partner MAC The chassis MAC address on the other ServerIron ADX, indicating Layer 2 connectivity between the ServerIron ADXs. If this field contains all zeros, double-check the connection between the ServerIron ADXs and verify that both ServerIron ADXs are powered on. Also verify that Spanning Tree is disabled on both ServerIron ADXs. Spanning Tree interferes with Hot Standby HA.

SLB Partner port cnt The number of physical ports on the other ServerIron ADX.

Transitions, activates The number of times this ServerIron ADX has changed from standby to active.

Transitions, standby The number of times this ServerIron ADX has changed from active to standby.

Pdus sent The number of Layer 4 synchronization packets this ServerIron ADX has sent to the other ServerIron ADX.

Mac pdu sent The number of MAC-layer synchronization packets this ServerIron ADX has sent to the other ServerIron ADX.

No pdus The number of missed Layer 4 or MAC-layer PDUs.

no port maps The number of missed port map PDUs. Port map PDUs are used by the ServerIron ADX to discover information about the maps on the other ServerIron ADX.


Hot Standby HA 6

Additional configuration variations

VIP and servers in different subnets

Figure 39 shows a configuration with the VIP and servers in different subnets.

FIGURE 39 VIP and servers in different subnets


Hot Standby HA6

Source-NAT in Hot Standby HA

NOTEThe status of the source NAT IPs is not updated for Hot Standby HA topology (since it is active on the ServerIron ADX which is Active/Standby and vice versa), and the show server source-nat-ip command will always show their status as enabled. The status of the source NAT IPs is relevant for Symmetric Active-Standby HA and Symmetric Active-Active HA topologies and will be displayed appropriately as Symmetric Active-Standby HA in these topology types.

The server source-nat command is added to the following configuration on both ServerIron ADXs. However, seamless failover cannot be achieved here. Refer to “Seamless failover in Hot Standby HA when Source-NAT enabled” on page 393

FIGURE 40 Source-NAT enabled in Hot Standby HA

.


Hot Standby HA 6

Seamless failover in Hot Standby HA when Source-NAT enabled

FIGURE 41 Seamless failover in Hot Standby HA when Source-NAT enabled

Configuring a backup group ID

You can configure up to 127 Hot Standby HA pairs within a single L2 broadcast domain. To enable this support, use the server backup-group command to configure a backup group ID on each of the ServerIron ADXs, so that both ServerIron ADXs in a given pair have the same ID. The backup group ID uniquely identifies the pair.

When you configure a backup group ID, both ServerIron ADXs in a Hot Standby HA pair use the ID when exchanging backup information. If a ServerIron ADX receives a backup information packet, but the packet’s backup group ID does not match the ServerIron ADX’s backup group ID, the ServerIron ADX discards the packet.

If the broadcast domain contains multiple Hot Standby HA pairs, you must configure backup group IDs on all pairs. If the broadcast domain contains only one Hot Standby HA pair, you do not need to configure a backup group ID.

To configure a backup group ID, enter the following command.

ServerIronADX(config)#server backup-group 1

Syntax: [no] server backup-group id

The id variable specifies the backup group ID, which can be a number from 1 to 7. The default value is 0. Enter the same ID on both ServerIron ADXs in a Hot Standby HA pair. Do not enter the same ID on a ServerIron ADX that is not one of the ServerIron ADXs in the Hot Standby HA pair.


Hot Standby HA6

Setting the backup timer

The standby ServerIron ADX assumes the active role if the it does not receive a Hello message or Layer 4 session synchronization data from the active ServerIron ADX within a certain number of seconds since having received the last Hello message or synchronization data.

By default, the standby ServerIron ADX waits one second since having received the last Hello message or data to receive a new message or data. If the standby ServerIron ADX does not receive a new Hello message or data within one second, the standby ServerIron ADX assumes that the active ServerIron ADX is no longer available and takes over the active role.

In some configurations, particularly those in which the active ServerIron ADX is performing a lot of processing, it is possible for frequent failovers to occur. In this situation, although the active ServerIron ADX is still available and actively serving load balancing or other requests, the active ServerIron ADX does not always send the Hello message or synchronization data in time for the standby ServerIron ADX. As as result, the standby ServerIron ADX takes over the active role. If similar conditions cause the newly active ServerIron ADX to sometimes miss sending the Hello messages or synchronization data in time, failover occurs again.

You can prevent unnecessary state flapping between the two ServerIron ADXs by increasing the backup timer. When you increase the backup timer, the standby ServerIron ADX waits longer to receive new Hello messages or synchronization data from the active ServerIron ADX. As a result, flapping is reduced or eliminated.

NOTEThe backup timer must have the same value on both ServerIron ADXs in the Symmetric Active-Standby HA pair.

To set the backup timer on a ServerIron ADX in a Symmetric Active-Standby HA pair, enter the following command.

ServerIronADX(config)#server backup-timer 50

This command sets the backup timer to 5 seconds (50 * 100 milliseconds).

Syntax: [no] server backup-timer time

The time variable specifies how long the ServerIron ADX, when it is the backup ServerIron ADX, will wait for a Hello message or synchronization data from the active ServerIron ADX before assuming the active ServerIron ADX is no longer available. You can specify a value from 5 (one half second) through 100 (10 seconds), in units of 100 milliseconds each. The default is 10 (one second).

Enabling backup preference

You can configure one of the ServerIron ADXs in the Symmetric Active-Standby HA pair to always be the active ServerIron ADX. When you enable server backup-preference on one of the ServerIron ADXs, that ServerIron ADX is always active by default. The only event that can cause the other ServerIron ADX to be active is unavailability of the default active ServerIron ADX or its link to the backup ServerIron ADX. To allow graceful insertion, the ServerIron ADX does not immediately assume the active role, but instead waits for a configurable number of minutes before taking the active role.

To enable server backup preference, enter the following command.

ServerIronADX(config)#server backup-preference 5

Syntax: [no] server backup-preference wait-time


Hot Standby HA 6

The wait-time variable specifies how long the ServerIron ADX waits before assuming the active role. The ServerIron ADX does not immediately become the active ServerIron ADX but instead waits the number of minutes you specify. You can specify from 5 through 30 minutes. This variable does not have a default.

Configuring failover based on active VIP count

By default, the Symmetric Active-Standby HA peer failover is based on router ports and server ports. You can configure the Symmetric Active-Standby HA peer to fail over based on router ports and active VIP counts instead of just the router ports. When this type of failover is configured, the following occurs:

• If neither of the two nodes in the peer has any router ports, the one having more active-VIPs will be the active node; no status change if the active-VIPs also tie.

• If one node has no router ports, but another has at least one router port, the latter will be the active node.

• If both nodes have at least one router port, the one having more active-VIPs will be the active node. If active-VIPs tie, the node with more router ports will be the active node. There is no status change if both active-VIPS and router ports tie.


ServerIronADX(config)#server backup-vip-cnt

Syntax: [no] server backup-vip-count

Configuring failover based on the number of active virtual ports

You can configure the Symmetric Active-Standby HA peer to fail over based on router ports and active virtual ports, instead of just the router ports (default) or the combination of router ports and virtual servers as described in “Configuring failover based on active VIP count”. When a failover is configured to be based on the number of active virtual ports, the following occurs:

• If neither of the two nodes in the peer has any router ports, the one having more active VIP/VPORT counts will be the active node; no status change if the number active VIP/VPORT counts ties.

• If one node has no router ports, but another has at least one router port, the latter will be the active node.

• If both nodes have at least one router port, the one having more active VIP/VPORT counts will be the active node. if the number of active VIP/VPORT counts tie, the node with more router ports will be the active node. There is no status change if the number of both active virtual ports and router ports tie.


ServerIronADX(config)#server backup-vport-cnt

Syntax: [no] server backup-vport-count


Hot Standby HA6

This feature can be configured with or without the server backup-vip-cnt command as described:

• If the server backup-vport-cnt command is not configured, only the number of active virtual ports is compared. The node with more active virtual ports will be considered to have more VIP/VPORT counts, and a tie is called if they have an equal number of active virtual ports.

• If both the server backup-vip-cnt and server backup-vport-cnt commands are configured, the number of active virtual ports will have a higher precedence than the number of active virtual servers. Consequently, the node with a larger number of virtual ports will always be considered as having a higher VIP/VPORT count and in the case of a tie on the active virtual port count, the node with a larger number of active virtual servers will be considered as having a higher VIP/VPORT count. A tie condition occurs where both nodes have an equal number of both virtual servers and virtual ports.

NOTEThe server backup-vport-cnt command must be configured on both ServerIron ADX switches in the pair. To avoid an unnecessary failover during configuration, we suggest that you enable this feature on the active switch first. Also, the feature should be disabled on the standby switch first.

Delayed failover

With this feature configured, when a ServerIron ADX switch detects a failover condition because of a VIP/VPORT count change, the failover will be delayed. At the end of the period of delay, the ServerIron ADX switch examines the conditions that led to the failover condition and performs a failover if the conditions still apply. If they no longer apply, the failover will be cancelled.


ServerIronADX(config)#server backup-delay-seconds 20

Syntax: [no] server backup-delay-seconds backup-wait-seconds

The backup-wait-seconds variable specifies the number of seconds that the ServerIron ADX will wait before performing a failover. Values can be specified from 0 through 1200 seconds. Specifying 0 disables this feature and causes failover to occur immediately without any delay.

This feature applies only when configuring the server backup-vip-cnt or server backup-vport-cnt command.

NOTEThe server backup-delay-seconds backup-wait-seconds command must be configured on both ServerIron ADX switches in the active/standby pair.


Hot Standby HA 6

Configuring a ServerIron ADX to remain in standby state

This feature is specific to Hot Standby HA configurations. The feature lets you ensure that a ServerIron always remains in standby state, regardless of any changes in the system parameters (such as no heart beat, fewer router ports, and other changes). Use this feature when there is undesirable flapping between active and standby states, which can occur when the CPU utilization on the standby’s Management Processor is very high and causes the standby to drop the heart beat messages sent by the active ServerIron.

NOTEUse the remain-standby command with caution because both ServerIrons can become standbys; thereby creating traffic loss.

If the ServerIron is active when this command is configured, the ServerIron transitions to a backup state and remains as backup until the command is removed. The transition is logged as "Forced to turn standby" (remain-standby command.).

Once the remain-standby command is entered, every attempt the ServerIron makes to go into active state is recorded and suppressed. This information is available under the "Active attempts" field in the show server debug command.

To force a ServerIron to remain in the standby state, enter the following command.

ServerIronADX(config)#server backup-remain-standby

Syntax: server backup-remain-standby

Configuring the forwarding of synching messages

In a Hot Standby HA configuration, the active ServerIron ADX and the backup ServerIron ADX continuously communicate synching messages. These synching messages contain Layer 4 –Layer 7 session status information and are only used by the ServerIron ADXs.

Some of the messages can travel over a non-dedicated private link between the two ServerIron ADXs. Another ServerIron ADX can be in the middle of this link, acting as a Layer 2 or Layer 3 Switch passing traffic between the active and backup ServerIron ADXs.

In this situation, messages sent between the active and backup ServerIron ADXs can be intercepted and dropped by the ServerIron ADX in the middle, and not forwarded to the active or backup ServerIron ADXs. This could cause loss of synch between the active and backup ServerIron ADXs. To prevent this from happening, use the server fwd-l4-sync command to configure the ServerIron ADX in the middle to simply forward the synching messages and not intercept them.

To configure the ServerIron ADX in the middle to forward the synching messages, enter the following command on the ServerIron ADX connecting the active and the backup ServerIron ADXs.

ServerIronADX(config)#server fwd-l4-sync

Syntax: server fwd-l4-sync


Hot Standby HA6

Sample configurationSuppose you want to configure a second switch, ServerIron ADX2, to serve as the backup or standby switch for ServerIron ADX1. Each switch will be configured with the same SLB configuration, supporting the following TCP/UDP ports: HTTP, SSL, FTP, and Telnet.

The private link, which provides the connection between the active and standby switches, will be configured as a trunk group with ports 13 and 14 as members.

ServerIronADX#config termServerIronADX(config)#trunk server ethernet 13 to 14

For non-HA trunk links connected to other Layer 2 switches, use the default trunk switch. For non-HA trunk links connected to Dual-NIC servers, use the trunk server command.

On ServerIron ADX devices, if you configure a trunk group, use the trunk switch command if the traffic flowing through the trunk requires Layer 4-7 processing. Only use the trunk server command if the traffic flowing through the trunk does not require Layer 4-7 processing. For traffic that does not require Layer 4-7 processing on ServerIron ADX devices, the trunk type can be switch or server.

ServerIronADX(config)#vlan 2ServerIronADX(config-vlan-2)#untag ethernet 13 to 14ServerIronADX(config-vlan-2)#no spanning-treeServerIronADX(config-vlan-2)#exitServerIronADX(config)#server real web1 10.96.22.100ServerIronADX(config-rs-web1)#port httpServerIronADX(config-rs-web1)#port sslServerIronADX(config-rs-web1)#port ftpServerIronADX(config-rs-web1)#port telnetServerIronADX(config-rs-web1)#server real web2 10.96.22.101ServerIronADX(config-rs-web2)#port httpServerIronADX(config-rs-web2)#port sslServerIronADX(config-rs-web2)#port ftpServerIronADX(config-rs-web2)#port telnetServerIronADX(config-rs-web2)#server virtual-name-or-ip www.example7.com 10.96.6.254ServerIronADX(config-vs-www.example7.com)#port httpServerIronADX(config-vs-www.example7.com)#port ssl stickyServerIronADX(config-vs-www.example7.com)#port ftpServerIronADX(config-vs-www.example7.com)#port telnetServerIronADX(config-vs-www.example7.com)#bind http web1 http web2 httpServerIronADX(config-vs-www.example7.com)#bind ssl web1 ssl web2 sslServerIronADX(config-vs-www.example7.com)#bind ftp web1 ftp web2 ftpServerIronADX(config-vs-www.example7.com)#bind telnet web1 telnet web2 telnetServerIronADX(config-vs-www.example7.com)#exit

To identify the router port, configure the trunk group, assign ports 13 and 14 as the backup ports, assign round robin as the predictor (load balancing metric), and disable Spanning Tree, enter the following commands.

ServerIronADX(config)#server router-ports 11ServerIronADX(config)#server backup ethernet 13 00e0.5201.0c72ServerIronADX(config)#server predictor round-robinServerIronADX(config)#no spanServerIronADX(config)#exitServerIronADX#write memoryServerIronADX#reload


Symmetric Active-Standby HA 6

The MAC address assigned is a MAC address that is resident on either ServerIron ADX1 or ServerIron ADX2. Notice that because port 13 is the lead port for the trunk group, you do not need to configure any other ports within that group.

Symmetric Active-Standby HABoth ServerIron ADXs handle traffic, but the active VIP handles the L4-7 and the standby VIP serves only as a standby. Each ServerIron ADX is the active ServerIron ADX for a specific set of VIPs, while the other ServerIron ADX is the backup for the same set of VIPs.

In Symmetric Active-Standby HA, you determine which ServerIron ADXs are active and backup for a VIP by associating the sym-priority command with the VIP. You assign a different priority to the same VIP on each ServerIron ADX. The ServerIron ADX on which the VIP has the highest priority is the active ServerIron ADX for that VIP, and the others are standbys. When all ServerIron ADXs and associated links are available, the ServerIron ADX with the highest priority for the VIP services the VIP.

Symmetric Active-Standby HA does not require any changes to the Spanning Tree configuration in the network. Regardless of whether the network is using Spanning Tree, Symmetric Active-Standby HA provides redundancy for the VIPs and allows all the ServerIron ADXs configured for Symmetric Active-Standby HA to actively perform server load balancing.

In addition, you do not need to dedicate ServerIron ADX links to Symmetric Active-Standby HA. Symmetric Active-Standby HA works within the network’s topology.

NOTEYou cannot have a router hop between the ServerIron ADXs. They must have Layer 2 connectivity. Additionally, you cannot use Hot Standby HA and Symmetric Active-Standby HA features on the same ServerIron ADX.

NOTEIf a ServerIron ADX is running software with a router image and the ServerIron ADXs are in an active-active configurations, you need to enable VRRP or VRRP-E on these ServerIron ADXs; otherwise, FTP, RTSP, and MMS protocols might not work. Also, configure the IP address of the real server’s default gateway IP address in VRRP-E configuration and the "owner" IP address in VRRP configuration. It is important that the default gateway should be defined. If it is not defined, then SI does not send the Gratuitous ARP immediately after the VRRP and VRRPE switchover.

NOTEThe ServerIron ADX does not support Symmetric Active-Standby HA with shared source NAT IPs. The reason is that the VIP and the source IP might not be active on the same ServerIron ADX, and as a result, the ServerIron ADX does not know how to forward return traffic. Configure Symmetric Active-Active HA as a workaround.

Configuring Symmetric Active-Standby HAIn Figure 42, two upstream routers are connected to two different ISPs. This setup allows clients to access the ServerIron ADXs from different directions. Clients coming from ISP1 want an active VIP1 (on ServerIron ADX-A). The same VIP1 accessed by ISP2 is on standby (on ServerIron ADX-B). On a per-ServerIron ADX basis, some VIPs are active while others are on standby. In contrast, all VIPs per ServerIron ADX are either active or standby in a Hot Standby HA scenario.


Symmetric Active-Standby HA6

To configure Symmetric Active-Standby HA, configure the sym-priority value command on each active and standby VIP. The higher the value, the higher the preference (priority). The range is from 0 through 255. You also can configure the priority to dynamically adjust to changes in the health of applications on the VIP.

In Figure 42, ServerIron ADX-A’s VIP1 has a priority of 10. ServerIron ADX-B’s VIP1 has a priority of 5. Therefore, ServerIron ADX-A is active. When traffic comes to VIP1, ServerIron ADX-A creates the session. When VIP1 on ServerIron ADX-A goes down, VIP1 on ServerIron ADX-B becomes active. Only the active VIP owner responds to ARP, traffic, session synching, and so on. The Symmetric solution provides granular control of the VIPs.

FIGURE 42 Common Symmetric configuration

Enabled by default, any Layer 2 link can be used for automatic session synchronization between the ServerIron ADXs. Unlike Hot Standby HA, the ServerIron ADXs need not be directly connected. To specify a specific port (optional), use the session-sync server subcommand on both devices. Refer to “Configuring VLAN option for active-active links” on page 411.



NOTETo correctly handle the return traffic in this scenario, apply Source-NAT or DSR to a Symmetric Active-Standby HA configuration. Enable one or the other (not both) for a real server.

Figure 43 shows another common Symmetric topology, where the real servers are directly connected to the ServerIron ADXs.

FIGURE 43 Common Symmetric configuration

NOTETo see the session sync, go to the BP and issue the show session all 0 command.

Failover conditions

Both ServerIron ADXs are active with Symmetric Active-Standby HA. Therefore, failover depends on which device has ownership of the VIP. If a link is broken, both ServerIron ADXs are still active. In general, the only time a VIP can fail over is during a reload or system crash. VIPs can fail over if they meet the conditions described on “VIP failover following a link failure” on page 409. Use the show log command to gather failover information.

Enabling session synchronization on a port

For each port you use for load balancing, you must define the session-sync command and port number to enable session synchronization.



NOTEThe session-sync command must to be enabled for all defined virtual and real ports.

As an example, to enable session synchronization for port 80 (HTTP), enter the following commands.

ServerIronADX(config)#server port 80ServerIronADX(config-port-80)#session-sync


Syntax: [no] session-sync

NOTEIssuing the no server port 80 command with the session-sync enabled command does not stop the session synchronization for port 80 (HTTP).

NOTEIn case of port translation, enable session synchronization for both the VIP virtual port and the real server port.

Additional configuration variations

Configuring the interval and wait time for Symmetric Active-Standby HA discovery packets

A ServerIron ADX in an Symmetric Active-Standby HA configuration uses discovery packets to request Symmetric Active-Standby HA information from the other ServerIron ADXs. Symmetric Active-Standby HA discovery packets are proprietary Layer 2 broadcast packets and are sent on all ports in all port-based VLANs. Use the server sym-pdu-rate command to change the interval and wait time for Symmetric Active-Standby HA discovery packets.

By default, a ServerIron ADX in a Symmetric Active-Standby HA configuration sends discovery packets at 200-millisecond intervals while the default wait time interval is twice the send interval at 400-milliseconds. In other words, Symmetric Active-Standby HA discovery packets are sent at every 200 milliseconds, but a recipient checks once in every 400 milliseconds to see whether the packets are received. The ServerIron ADX waits up to 20 equivalent intervals to receive a discovery packet from another ServerIron ADX. If the ServerIron ADX does not receive a discovery packet from the other ServerIron ADX within 20 intervals, the ServerIron ADX concludes that its partner ServerIron ADX is unavailable and assumes control of the VIPs being managed by that ServerIron ADX. For example, if the interval for sending Symmetric Active-Standby HA discovery packets is 200 milliseconds (the default), the ServerIron ADX waits 20 X 400 milliseconds (eight seconds) to receive a discovery packet from another ServerIron ADX.

You can change the send interval multiplier and the wait time multiplier.

• The send interval is equal to 200 milliseconds multiplied by the send interval multiplier. The default send-interval multiplier is 1, so the default send interval is 200 milliseconds. You can specify a multiplier from 1–60.

• The total wait time interval is equal to 400 milliseconds multiplied by the wait time multiplier. The default wait time multiplier is 20; therefore, the default wait time is eight seconds (20 x 400 milliseconds).



The Symmetric Active-Standby HA timer affects the rate at which the ServerIron ADX sends Symmetric Active-Standby HA protocol packets to its Symmetric Active-Standby HA partners. The timer does not affect client or server traffic to or from a VIP.

All the ServerIron ADXs in your configuration must use the same Symmetric Active-Standby HA send interval and wait time. If you change the interval and wait time on one ServerIron ADX, make the same change on all the other ServerIron ADXs in the Symmetric Active-Standby HA configuration.

To configure the interval and wait time for Symmetric Active-Standby HA discovery packets, enter a command such as the following.

ServerIronADX(config)#server sym-pdu-rate 2 30

This command does the following:

• Changes the default send interval (200 ms) and wait interval (400 ms) by a factor of 2

• Increases the wait time multiplier from the default 20 to 30

In effect, this command:

• Changes the interval at which the ServerIron ADX sends Symmetric Active-Standby HA discovery packets to once every 400 milliseconds

• Changes the wait interval for discovery packet to once every 800 milliseconds

• Changes the maximum amount of time the ServerIron ADX will wait for a Symmetric Active-Standby HA discovery packet from another ServerIron ADX to 24 seconds (30 x 2 x 400 milliseconds).

Syntax: [no] server sym-pdu-rate send-wait-multiplier wait-time-multiplier

The send-wait-multiplier variable specifies the multiplier for the Symmetric Active-Standby HA send and wait interval. You can specify a multiplier from 1–60. The default is 1.

The wait-time-multiplier variable specifies how many multiples of the wait interval the ServerIron ADX will wait for a Symmetric Active-Standby HA discovery packet. You can specify a multiplier from 1–60. The default is 20.

Enabling synchronization link for Symmetric Active-Standby HA

You can specify a dedicated link (port and VLAN ID) for symmetric packets such as, session synchronization packets and VIP sym-priority packets. When you enable this feature and the dedicated link goes down, the ServerIron ADX will automatically detect this and revert back to the dynamic detection of communication links.

To enable this feature, enter a command such as the following.

ServerIronADX(config)#server symmetric-port ethernet 1/2 vlan-id 101

Syntax: [no] server symmetric-port slot num/port num vlan ID

Enabling backup trunk port

For Hot Standby HA, the number of available ports in a trunk is counted in number of router or server ports. If both ServerIron ADXs have 4-port trunks as router ports, for example, the router port count is now 4 (it was 1). If one port of the trunk in ServerIron ADX-1 is down and ServerIron ADX-1 is active, ServerIron ADX-2 will become active, and ServerIron ADX-1 will become standby.



Use the server backup-trunk-port-cnt command to enable this functionality, as shown in the following.

ServerIronADX(config)#server backup-trunk-port-cnt

Syntax: [no] server backup-trunk-port-cnt

Setting Symmetric Active-Standby HA priority

If you are configuring a pair of ServerIron ADXs to provide redundancy for individual VIPs, you must specify an SLB priority on each ServerIron ADX for each of the VIPs. The ServerIron ADX with the higher priority for a given VIP is the default active ServerIron ADX for that VIP. The other ServerIron ADX is the default standby for the VIP.

To specify the priority, enter a command such as the following.

ServerIronADX(config)#server virtual-name-or-ip noi-is-cool 10.2.3.4ServerIronADX(config-vs-noi-is-cool)#sym-priority 254

Syntax: sym-priority num

You can specify from 0 through 255. If you specify 0, the priority setting is removed.

NOTEBrocade recommends that you specify 2 (instead of 1) as a low priority or 254 (instead of 255) as a high priority. This way, you can easily force failover of the high priority ServerIron ADX to the low priority ServerIron ADX by changing the priority on just one of the ServerIron ADXs. For example, you can force a failover by changing the priority on the high priority ServerIron ADX from 254 to 1. Because the priority on the low priority ServerIron ADX is 2, the low priority ServerIron ADX takes over for the VIP. Likewise, you can force the low priority ServerIron ADX to take over by changing its priority to 255, because the priority on the high priority ServerIron ADX is only 254.

Configuring dynamic priority

The software automatically adjusts a VIP application’s symmetric priority to a lower value if a given application fails a health check. With this enhancement, the symmetric priority provides failover for the individual application even if the ServerIron ADX and the application’s VIP are both still active.

The priority determines which ServerIron ADX becomes the active one for the VIP and application by default. The priority is static and does not change if the status of the VIP’s application changes. As a result, it is possible for Symmetric Active-Standby HA to continue trying to use a real server farm that is no longer responding, instead of failing over to the other ServerIron ADX to load balance requests for the VIP and application.

You can configure a decrement value for the Symmetric Active-Standby HA priority. If an application on a VIP that is enabled for Symmetric Active-Standby HA fails a health check, the ServerIron ADX decrements the VIP’s symmetric priority by the amount you specify for the decrement. If the priority value becomes lower than the VIP’s priority on the other ServerIron ADX, the software fails the VIP over to the other ServerIron ADX.

NOTEWhen you configure a decrement value, the value takes effect only if all the application’s ports on the real servers fail their health checks. Thus, if the application is still available on at least one of the real servers bound to the VIP, the software does not decrement the priority.



NOTEWhen you configure the decrement value, do not specify a value that will make the VIP’s priority 0. For example, if the VIP’s symmetric priority is 10, do not specify 10 as the decrement value. Specify a lower number. Priority value 0 disables Symmetric Active-Standby HA, in which case the VIP becomes active on both ServerIron ADXs.

Figure 44 shows an example of a Symmetric Active-Standby HA configuration that uses the default

priority handling (not the dynamic priority handling).

FIGURE 44 Symmetric Active-Standby HA without dynamic priority

Using the default priority handling, the software fails over a VIP to the other ServerIron ADX only of the entire VIP or the ServerIron ADX itself becomes unavailable. If an application on the VIP becomes unavailable on all the real servers bound to the VIP, but the VIP itself is still available, the software continues using the same ServerIron ADX for the VIP. As a result, clients are unable to access the unavailable application even if the application is available through the other ServerIron ADX.



Figure 45 shows an example of a configuration that uses dynamic Symmetric Active-Standby HA priority.

FIGURE 45 Symmetric Active-Standby HA with dynamic priority

In this configuration, a ServerIron ADX fails over a VIP to the other ServerIron ADX if more than one application on the VIP becomes unavailable. If one application becomes unavailable, the software reduces the VIP’s priority by 9 (the decrement value), in this case to 21. At this point, the ServerIron ADX that is active by default for the VIP still has the higher priority, so failover does not occur. However, if a second application becomes unavailable, then the priority becomes 12, which is less than the priority for the VIP on the other ServerIron ADX (20).

When an application becomes available again (and passes a health check), the ServerIron ADX increments the VIP’s priority by the decrement amount, thus replacing the priority amount that the software removed when the application failed. If the increment makes the VIP’s priority higher than the priority on the other ServerIron ADX, the software fails back over to the ServerIron ADX that originally had the higher priority for the VIP.

If more than one ServerIron ADX has the highest priority for a VIP, the ServerIron ADX that has the highest value for the lowest four bytes of its base MAC address becomes the active ServerIron ADX for the VIP.

NOTEIf all the applications that are configured for Symmetric Active-Standby HA on the VIP become unavailable, the software sets the symmetric priority for that VIP to 1 (the lowest value).

The following commands configure the symmetric priority parameters for the configuration in Figure 45.



Setting the symmetric MAC address

On a ServerIron ADX, the MAC address for the VIPs, source-nat ips and IP NAT ips is derived from the first three bytes of the chassis MAC address. For instance, if the chassis MAC address is 000c.db12.1234, the MAC address for VIPs and NAT ips would be based on 000c.db00.0000.

In Symmetric/Symmetric Active-Active HA, this is known as the symmetric mac and both the boxes need to derive the MAC address for VIPs and NAT ips from the same base MAC address.

In the event that an HA pair share the same first 3 bytes of the chassis MAC address, the symmetric mac will be the same on both the boxes. In the event that the HA pair do not share the same first 3 bytes of the chassis MAC address, the higher of the two chassis MAC addresses is automatically chosen as the symmetric mac. For example, if Box A has a chassis MAC address of 000c.db12.1234 and Box B has a chassis MAC address of 001b.db12.2345, symmetric mac would be automatically set to 001b.db00.0000, when both the boxes are brought up.

Alternatively, symmetric mac can be manually configured based on one of the box's chassis MAC addresses. Use the sym-mac command to configure a symmetric mac as shown in the following.

ServerIronADX#configure terminalServerIronADX(config)#sym-mac 001b.db00.0000

Syntax: sym-mac sym-mac-address

The sym-mac-address variable specifies the first 3 bytes of the chassis MAC address of one of the boxes in the HA setup.

Considerations when using this commandConsider the following when using the sym-mac command.

• Addition or deletion of this command requires a reload. Once configured, it is required to write memory and reload the box in order for the command to take effect.

• When manually configuring symmetric mac, it is required to configure the same sym-mac command on both the devices in the HA setup.

• Manual configuration of symmetric mac overrides the auto detection. When manually configured, the symmetric mac used will be the configured value only.



Displaying the symmetric macThe show server virtual command can be used to view the symmetric mac that the boxes use to derive the VIP and NAT IP MACs. The display from this command includes a field named symmetric mac, as shown in the following.

Configuring delay reactivation

Use the server delay-symmetric command to delay the reactivation of a failed ServerIron ADX in a Symmetric Active-Standby HA configuration following the ServerIron ADX’s recovery. By delaying reactivation of a recovered ServerIron ADX, you provide time for sessions created by the standby ServerIron ADX to terminate normally.

When you enable session synchronization in a ServerIron ADX Symmetric Active-Standby HA configuration, the active ServerIron ADX for a VIP sends session synchronization information to the standby ServerIron ADX. If the VIP’s active ServerIron ADX becomes unavailable, the open sessions for the VIP fail over to the other ServerIron ADX, which provides uninterrupted service for the sessions.

The active ServerIron ADX sends session synchronization information to a VIP’s standby ServerIron ADX when the session is created. Following a failover, when the standby ServerIron ADX for a VIP has taken over, the standby ServerIron ADX can create new sessions for the VIP. However, because the ServerIron ADX with the higher priority for the VIP is unavailable, the standby ServerIron ADX cannot send synchronization information for the newly created sessions. As a result, when the other ServerIron ADX becomes available again, it resumes service for the VIP but cannot continue the sessions that were created by the standby ServerIron ADX.

You can minimize interruption to sessions created on the standby ServerIron ADX by configuring each ServerIron ADX to delay reactivation following its recovery after a failover. By delaying reactivation of a recovered ServerIron ADX, you provide time for sessions created by the standby ServerIron ADX to terminate normally.

ServerIronADX#show server virtualVirtual Servers Info

Name: vip441 State: Enabled IF UP IP:10.1.1.200: 1Pred: least-conn ACL-Id: 0 TotalConn: 240Sym: group = 1 state = 5 priority = 200 keep = 0 dyn priority/factor = 200/ 0 Activates = 1, Inactive= 1 sym-active = 1 Sym Priority = Enabled Symmetric VIP state: Owner Symmetric MAC: 748e.f800.0000Best-standby-mac: 748e.f800.245aVIP state: healthy

Port State Sticky Concur Proxy DSR CurConn TotConn PeakConn ---- ----- ------ ------ ----- --- ------- ------- --------

default enabled NO NO NO NO 0 0 0 http enabled NO NO NO NO 13 22 14 dns enabled NO NO NO NO 0 22 0 ftp enabled NO NO NO NO 64 196 156



To configure delay reactivation, enter the following command.

ServerIronADX(config)#server delay-symmetric

Syntax: [no] server delay-symmetric [mins]

The mins variable specifies the number of minutes you want the recovered ServerIron ADX to wait before becoming active again. You can specify from 1 through 120 minutes. The default is 60 minutes. You must enter the same command using the same number of minutes on both ServerIron ADXs in the configuration.

NOTEThe server delay-symmetric command will only take effect when the ServerIron ADX is reloaded after it has been configured for the first time.

NOTEThe server delay-symmetric command will not take effect when sym-priority is changed manually.

NOTEThe ServerIron ADX delay reactivation feature using the server delay-symmetric command was introduced because "fast session sync" was not yet supported. Currently, the ServerIron now support fast session sync to synchronize all the sessions when any of the ServerIron ADX reloads.

VIP failover following a link failure

In an active-active SLB configuration, each VIP is managed by one of the ServerIron ADXs by default. The other ServerIron ADX is a backup for the VIP.

If the interface that has the VIP’s subnet becomes unavailable on the default active ServerIron ADX for the VIP, the ServerIron ADX changes the symmetric priority for that VIP to 1 to cause a failover to the other ServerIron ADX. Once the unavailable link is restored, the ServerIron ADX changes the symmetric priority back to the value you configured.

NOTEFailover occurs only if the entire link becomes unavailable. If the link is a trunk group or a virtual routing interface residing on multiple ports, failover occurs only if all the ports become unavailable. Under Layer 2 switching code, interfaces do not belong to individual subnets. As a result, under Layer 2 switching code Symmetric Active-Standby HA VIP failover can only happen in the case of a reload or system crash.

NOTEOn the current VRRP-e backup, the current sym-priority of all VIPs listed in a VIP group will become 1, and their sym-priority values will display as “Disabled”. This is normal behavior and ownership of these VIPs will follow the VRRP-e master.



Configuring VIP failover in VRRP extended with Symmetric Active-Standby HAIn Symmetric Active-Standby HA and Symmetric Active-Active HA configurations with VRRP-E, when the device switches from the Master router to a Backup router, there is a CLI command that guarantees simultaneous VIP failover in the event VRRP-E fails over to a Backup router. To enable this feature, first define a VIP group that includes VIP addresses, then bind the VIP group to a Virtual Router ID (VRID).

NOTEBefore defining and binding VIP groups, ensure that the standby VIP priority (sym-priority command) is not set to 1. This value is reserved for internal use.

NOTEIn Symmetric Active-Standby HA, the VIP is active on both ServerIron ADXs if there is no default gateway configured, even though all clients, servers, and ServerIron ADXs are on the same subnet.

To enable the VIP failover in VRRP extended with Symmetric Active-Standby HA, enter commands such as the following.

1. Define a VIP group.

ServerIronADX(config)#server vip-group 1ServerIronADX(config-vip-group-[1])#vip 10.10.1.100ServerIronADX(config-vip-group-[1])#exit

2. Bind the VIP group to a VRID.

ServerIronADX(config)#router vrrp (-extended)ServerIronADX(config)#interface e 1/2ServerIronADX(config-if-e100-1/2)#ip vrrp vrid 1ServerIronADX(config-if-e100-12-vrid-1)#vip-group 1

NOTEEach virtual IP address can belong to only one VIP group. Also, each VIP group can have only one VRID associated with it.

Enhanced VIP group supportThe ServerIron VIP Group feature helps grouping of several virtual server addresses and associating them with the VRRP-E tracking mechanism.

Syntax: [no] server vip-group number

The number variable is the VIP group number from 1 through 100.

Syntax: [no] vip ip address

The ip address variable is the Virtual IP address to be included in the VIP group. There is not limit to the number of Virtual IP addresses in a VIP group; however, each virtual IP address can belong to only one VIP group.

Syntax: [no] vip-group number

The number variable is the VIP group number (from 1 through 100) that you are binding to the VRID. Note that each VIP group can have only one VRID associated with it.



Configuring VLAN option for active-active links

Active-active SYN-Guard and NAT configurations use the server active-active-port ethernet portnum command to identify the port that connects the ServerIron ADX to its active-active partner. The port you specify must be in its own port-based VLAN.

To use a tagged port, specify the VLAN ID for the active-active link when you specify the port. When you specify the VLAN ID, the ServerIron ADX forwards active-active traffic on the specified VLAN only. The traffic is not sent to the other VLANs of which the port is a member.

To configures the active-active link, enter the command such as the following.

ServerIronADX(config)#server active-active-port ethernet 3/5 200

This command configures the active-active link on port 3/5 on VLAN 200 only. The active-active traffic is not forwarded to the other VLANs that port 3/5 is in.

Syntax: [no] server active-active-port ethernet portnum [vlan-id]

NOTEIn ServerIron ADX device, you don't need to configure static-mac-address for active-active-port.

Allowing pass-through traffic to a VIP

In a symmetric-active SLB configuration, the ServerIron ADX intercepts SYN packets to a VIP if the destination MAC address is not the VIP's MAC address.

The server allow-pass-through-vip-traffic command causes the ServerIron ADX to ignore SYN packets addressed to a symmetric VIP IP address if the destination MAC address is not the symmetric VIP MAC address.

To allow pass-through traffic to a VIP, enter the following command.

ServerIronADX(config)#server allow-pass-through-vip-traffic

Syntax: [no] server allow-pass-through-vip-traffic

Fast session synchronization with VRRP

ServerIron ADXs in symmetric high-availability configuration will support the fast session synchronization. Fast session synchronization applies to symmetric and symmetric-active topologies. With the fast session synchronization, if a software reload occurs in one ServerIron ADX, the other ServerIron ADX in the symmetric high-availability pair synchronizes all existing sessions with the newly reloaded ServerIron ADX. This process ensures that multiple failovers for symmetric high-availability ServerIron ADXs occur seamlessly and without loss of traffic.

Fast session synchronization is enabled by default. There are no CLI commands to enable or disable this feature. However, if VRRP is configured on your ServerIron ADXs you need to configure a primary and secondary IP address on the VRRP interface of the VRID owner. The secondary IP address must be associated with the VRID.



FIGURE 46 Fast session synchronization with VRRP

NOTEAssociating the secondary IP with the VRID and other configuration mentioned above is a requirement only for VRRP. There is no such requirement for VRRP-E in order to support fast session synchronization feature.

The following configuration examples below show how to configure the VRRP owner and backup with the primary and secondary IP addresses.



VRRP-E track port increase

You can configure sixteen track ports with priority for a VRRP-E instance. Prior to this release, you could only configure eight track ports.

The following example shows how to configure VRRP-E with priority.

ServerIronADX(config)#interface ve 2ServerIronADX(config)#ip address 172.20.1.222 255.255.255.0ServerIronADX(config)#ip vrrp-extended vrid 2ServerIronADX(config)#backupServerIronADX(config)#ip-address 172.20.1.221ServerIronADX(config)#track-port e 4/9 priority 09ServerIronADX(config)#track-port e 4/10 priority 10ServerIronADX(config)#track-port e 4/11 priority 11ServerIronADX(config)#track-port e 4/12 priority 12ServerIronADX(config)#track-port e 4/13 priority 13ServerIronADX(config)#track-port e 4/14 priority 14ServerIronADX(config)#track-port e 4/15 priority 15ServerIronADX(config)#track-port e 4/16 priority 16ServerIronADX(config)#track-port e 4/17 priority 17ServerIronADX(config)#track-port e 4/18 priority 18ServerIronADX(config)#track-port e 4/19 priority 19ServerIronADX(config)#track-port e 4/20 priority 20ServerIronADX(config)#track-port e 4/21 priority 21ServerIronADX(config)#track-port e 4/22 priority 22ServerIronADX(config)#track-port e 4/23 priority 23ServerIronADX(config)#track-port e 4/24 priority 24

Syntax: [no] track-port interface priority value

Tracking trunk ports with VRRP-E

The ServerIron ADX allows you to configure trunk ports to provide the higher bandwidth required by many application switching network designs. If, however, an individual port within a trunk fails the expected throughput will fall but failover in a VRRP-E track port configuration will not occur unless all of the ports in the trunk fail.

The Track Trunk Port with VRRP-E feature allows the ServerIron ADX to track the failure of individual ports within a trunk. When a tracked port within a trunk fails, the VRID priority value is changed as described in the following:

• If all ports in the trunk are up, the VRID priority value is unchanged.

• If none of the ports in the trunk are up, the Track Priority is subtracted from the backup priority to determine the current VRID priority value.

• If any of the ports in the trunk fail, the following formula is used.

• A new Track Priority value is determined by the following formula: track priority x (number of configured ports in trunk - the number of active ports in trunk) ÷ number of configured ports in trunk

• The new Track Priority value is subtracted from the backup priority value to determine the current VRID priority.

Syntax: [no] track-trunk-port ethernet slot/port



Configuration considerationsThe following must be considered when configuring the Track Trunk port feature:

• This feature only applies to VRRP-E.

• Only ports that are members of a static trunk or are LACP enabled can be configured as track trunk ports.

• If a port that is not a member of a trunk group or LACP is configured as a track trunk port, it will behave like a track port.

• If different ports with the same trunk group are configured as track port and track trunk port, they will all behave as if configured as track trunk ports.

• Before removing a static trunk or LACP configuration, a port should be removed from the track trunk port list.

• Co-existence of track-port and track-trunk-port within the same trunk should be avoided.

• Co-existence of track-trunk-port and track-port ve with in the same trunk should be avoided.

• If you are using track-trunk-port, it is preferable to configure all the ports with in the trunk as track-trunk-ports.

• Where Track-trunk-port and Track-port VE pertaining to same trunk exists, the ServerIron ADX takes both into consideration when calculating VRRP-E Master and Backup selection. Add "track-port" before you add "track-trunk-port" for the same trunk.

Configuring tracking trunk ports with VRRP-ETo configure the tracking ports with the VRRP-E, enter the following commands.

ServerIronADX(config)#trunk switch e 4/9 to 4/10Trunk will be created in next trunk deploy.ServerIronADX(config-)#trunk deployServerIronADX(config)#int ve 1ServerIronADX(config-vif-1)#ip vrrp-extended vrid 1ServerIronADX(config-vif-1-vrid-1)#backup priority 200 track-priority 100

NOTEThe backup priority must be a decimal of 6 through 255 for vrrp-extended. The track-priority must be a decimal from 1 through 254.

ServerIronADX(config-vif-1-vrid-1)#track-trunk-port e 4/9

NOTEOptionally, you can specify track priority for the track-port. This overrides the track-priority specified in "backup priority x track-priority y".

ServerIronADX(config-vif-1-vrid-1)#track-trunk-port e 4/9 priority 80

NOTEThe track-port and track-trunk-port must be trunk primary, otherwise an error will be prompted.

ServerIronADX(config-vif-1-vrid-1)#track-port e 4/10Error - track port must be the first port of a trunk.

ServerIronADX(config-vif-1-vrid-1)#track-trunk-p e 4/10Error - track trunk port must be the trunk primary.



Sample configurationServerIronADX#sh run | i trunktrunk server ethe 4/1 to 4/4trunk server ethe 4/5 to 4/6trunk switch ethe 4/9 to 4/10ServerIronADX#sh run int ve 1!Building configuration...!Current configuration : 346 bytesinterface ve 1 ip address 10.2.2.21 255.255.255.0 ip vrrp-extended vrid 1 backup priority 200 track-priority 100 advertise backup ip-address 10.2.2.30 vip-group 1 track-trunk-port e 4/1 track-port e 4/5 track-trunk-port e 4/5 track-port e 4/9 track-trunk-port e 4/9 enable

To remove the track-port, track-trunk-port needs to be removed first.

ServerIronADX(config-vif-1-vrid-1)#no track-port e 4/9

You must disable track-trunk-port before the track-port.

ServerIronADX(config-vif-1-vrid-1)#

NOTETo remove trunk, track-trunk-port must be removed first.

ServerIronADX(config-vif-1-vrid-1)#no trunk swi e 4/9 to 4/10

You must remove the track-port in the VRRP-E configuration first. To configure this feature, follow these steps.

1. The following command can ONLY be configured for trunk primary.

ServerIronADX(config-vif-13-vrid-1)#track-trunk-port ethernet 4/34Error - track trunk port must be the trunk primary.ServerIronADX(config-vif-13-vrid-1)#

2. Add "track-port" before adding "track-trunk-port" for the same trunk.

ServerIronADX(config-vif-13-vrid-1)#track-trunk-port ethernet 4/33Must track-port this trunk before track-trunk-port the same trunkServerIronADX(config-vif-13-vrid-1)#

3. Add "no track-trunk-port" before adding "no track-port" for the same trunk.

ServerIronADX(config-vif-13-vrid-1)#no track-port e 4/33Must disable track-trunk-port before track-portServerIronADX(config-vif-13-vrid-1)#

Sample configurationIn the following configuration, both SI-A and SI-B share a trunk with a FastIron switch. The trunk has two ports (e4/33-34) and the primary trunk is e4/33. VRRP-E vrid 1 is configured in interface e4/17.


Symmetric Active-Active HA6

Symmetric Active-Active HASymmetric Active-Active HA is a true active-active. Both ServerIron ADXs handle traffic (active-active), and both ServerIron ADXs are active for the same VIP on both ServerIron ADXs.

Difference between Symmetric Active-Active HA versus Symmetric Active-Standby HAThe difference is minimal. For Symmetric Active-Active HA, the difference is that Symmetric Active-Active HA is configured on the VIP to enable the standby box to process traffic. The load and CPU processing per VIP is equally shared between both ServerIron ADXs, as shown in the Figure 47.

FIGURE 47 Comparing Symmetric Active-Active HA with Symmetric

When Symmetric Active-Active HA is enabled on both ServerIron ADXs, both boxes handle traffic equally for each VIP. A box with Symmetric Active-Active HA configured is enabled to process and forward traffic to and from the client, regardless of an assigned lower VIP priority.


Manual triggering of symmetric HA failover with VRRP-E 6

Configuring Symmetric Active-Active HATo enable the Symmetric Active-Active HA on each VIP, enter commands such as the following.

ServerIronADXA(config)#server virtual-name-or-ip VIP1 10.1.1.1ServerIronADXA(config-vs-VIP1)#port 80ServerIronADXA(config-vs-VIP1)#sym-priority 69ServerIronADXA(config-vs-VIP1)#sym-active

This example configures VIP1 by adding port 80, enabling Symmetric Active-Standby HA, then enabling Symmetric Active-Active HA. With Symmetric Active-Active HA, you still need to configure the sym-priority command. Whichever ServerIron ADX has the higher priority will own the VIP address, MAC, and ARP responses. If someone pings the VIP for example, only the active VIP will reply.

Syntax: [no] sym-active

NOTESource-NAT and DSR are usually not applied a Symmetric Active-Active HA configuration. The return traffic is correctly handled in this scenario. The active and standby ServerIron ADXs are constantly sharing information.

NOTEWhen using a pair of ServerIrons in an HA setup, configure Symmetric Active-Active HA in addition to Symmetric Active-Standby HA, VRRPE, and VIP groups. This is because VRRPE failover and Symmetric Active-Standby HA failover are two separate events. First, VRRPE failover occurs, followed by Symmetric Active-Standby HA failover. Configuring Symmetric Active-Active HA allows the ServerIron to cope with the miniscule window between those two events.

Manual triggering of symmetric HA failover with VRRP-EThe ServerIron ADX allows you to manually trigger a failover in a symmetric HA configuration with VRRP-E. This feature is useful when upgrading the active ServerIron ADX software or troubleshooting the ServerIron ADX. The ServerIron ADX transitions from active to standby seamlessly and no longer handles any traffic before the upgrade or troubleshooting process.

This feature uses VRRP-E to trigger the failover by lowering the VRRP-E priority to 1. When VRRP-E failover occurs, the ownership of all VIPs that are bound to a VIP group associated with a VRRP-E interface is transferred to the standby ServerIron ADX for the handling of all traffic.

NOTEThis feature works with VRRP-E only. You must configure all VIPs under a VIP group, and associate the VIP group to a VRRP-E interface.


Manual triggering of symmetric HA failover with VRRP-E6

Configuring manual HA failoverTo configure manual failover to the standby ServerIron ADX by dynamically setting the VRRP-E priority to 1 for all VRRP-E configurations on the active ServerIron ADX, use the vrrp-e standby command in EXEC or global configuration mode.

NOTEFor the VIPs to failover with the VRRP-E interface, you must configure all VIPs under a VIP group or groups and you must associate the group with the VRRP-E interface.

Example in global configuration mode

ServerIronADX(config)# vrrp-e standby

Syntax: [no] vrrp-e standby

In the case of an upgrade, when ServerIron ADX reboots, the original priority is restored and the ServerIron ADX becomes the active ServerIron ADX again. To reboot the ServerIron ADX with a VRRP-E priority set to 1 and to remain as the standby ServerIron ADX, use the write memory command before rebooting it to preserve the vrrp-e standby command. For more detailed information, refer to the “Upgrade process for the symmetric HA setup using VRRP-E” section.

Use the no form of the command to manually restore the priority to the original value and the ServerIron ADX becomes the VRRP-E owner.

Example in EXEC mode

ServerIronADX # vrrp-e standby

Syntax: vrrp-e standby [disable]

The disable option restores the original priority and transfers ownership to the ServerIron ADX with the highest priority.

NOTEIn EXEC mode, the vrrp-e standby command cannot be saved across reboots.

Upgrade process for the symmetric HA setup using VRRP-EThe upgrade process that uses VRRP-E to trigger a failover works only if VRRP-E is configured on the symmetric HA setup. You must configure all VIPs under a VIP group and bind the VIP group to a VRRP-E instance.

The configuration can have multiple VIP groups, but all VIPs must be under the VIP groups and the VIP groups must be bound to a VRRP-E instance. The following is a sample configuration.

server vip-group 1 vip 20.20.20.100 vip 20.20.20.101

server vip-group 99 vip 20.20.20.102 vip 20.20.20.103 vip 20.20.20.104 vip 20.20.20.105

interface ve 10 ip address 10.10.10.2 255.255.255.0


Manual triggering of symmetric HA failover with VRRP-E 6

ipv6 address 2001:10::2/64 ip vrrp-extended vrid 10 backup priority 99 advertise backup ip-address 10.10.10.254 vip-group 1 track-trunk-port e 1/1 enable!interface ve 11 ip address 11.11.11.2 255.255.255.0 ip vrrp-extended vrid 11 backup priority 99 advertise backup ip-address 11.11.11.254 vip-group 99 track-trunk-port e 1/1 track-port e 1/5 track-port ve 20 track-port ve 21 enable

After you enable VRRP-E and all VIPs are bound to a VRRP-E instance using the VIP-group configuration, you can use the vrrp-e standby command on the active ServerIron ADX to trigger the manual failover of the VRRP-E and the failover of all traffic to the standby ServerIron ADX, which becomes the active device. Then you can upgrade the current standby ServerIron ADX without affecting the traffic flow. The following table provides the upgrade process.

TABLE 40 Upgrade process for symmetric HA failover with VRRP-E

ServerIron ADX A ServerIron ADX B

ServerIron ADX A is the active device and the VRRP-E master. ServerIron ADX B is the standby device and the VRRP-E backup.1 Since this ServerIron ADX is the standby and

is not taking any traffic, upgrade the image on it without affecting any traffic.

2 After the upgrade is complete, verify that you have the correct image and configuration.

3 Configure the vrrp-e standby command at global configuration mode and execute the write memory command.Dynamically all VRRP-e instances reduce to backup priority to 1, causing ServerIron ADX B to take ownership. ServerIron ADX A becomes the standby device.VIP ownership is also transferred, as all VIPs are bound to the VRRP-e instance using the VIP group.

4 Upgrade the code and reload with new image.On reload, ServerIron ADX A comes up as VRRP-E backup with the backup priority of all VRRP-E instances still at 1 and remains the standby device.

5 Verify that the image and configuration are correct.

ServerIron ADX B becomes the active device and the owner for all VIPs, and starts handling traffic.

6 Configure the no vrrp-e standby command at global configuration mode and execute the write memory command again.

The VRRP-E backup priority is restored, and ServerIron ADX A becomes the VRRP-E master and the active device. It now receives all traffic.

ServerIron ADX B becomes the VRRP-E backup and the standby device.


Manual triggering of symmetric HA failover with VRRP-E6

NOTEThe write memory command is used to save the vrrp-e standby command in the startup-configuration. Upon reload when the device comes up, all VRRP-E instances remain in the Backup state.

Displaying the current VRRP-E priority statusTo display the current VRRP-E priority status, use the show ip vrrp-extended command.

ServerIronADX# show ip vrrp-e Total number of VRRP-Extended routers defined: 1Interface ethernet v10auth-type no authenticationVRID 10 state initialize administrative-status enabled standby enabled priority 100 current priority 1 hello-interval 1 sec dead-interval 0 sec current dead-interval 3.600 sec preempt-mode true virtual ip address 10.10.10.254 advertise backup: enabled

master router 10.10.10.2 expires in 00:00:02VRRP-e MAC address: 02e0.52a0.c00a

ServerIronADX# show ip vrrp-e briTotal number of VRRP-Extended routers defined: 1Standby enabled

Interface VRID CurPri P State Master addr Backup addr VIPv10 10 1 P Backup 10.10.10.2 Local 10.10.10.254

Syntax: show ip vrrp-extended [brief]

The brief option displays the VRRP-E status summary.

Table 41 describes the VRRP-E priority status fields for the show ip vrrp-extended command.

TABLE 41 Priority status displayed by the show ip vrrp-extended command

Field Description

Standby enabled Whether the ServerIron ADX is enabled as the standby by the vrrp-e standby command.

Priority The configured backup priority. This field is not available with the brief option.

Current Priority or CurrPri The current priority of the ServerIron ADX. If you configure the vrrp-e standby command, this field displays a setting of 1.


Orchestrating seamless HA failover using VRRP-E pool 6

Orchestrating seamless HA failover using VRRP-E poolIn symmetric HA modes, a VIP group combined with VRRP-E tracking is used to achieve symmetric traffic flow. However, in certain failover situations where VRRP-E non-preemption is enabled, traffic symmetry may get disturbed, resulting in traffic loss.

FIGURE 48 HA pair configuration

In the network topology shown in Figure 48, the ADX-1 and ADX-2 devices are configured as a High Availability (HA) pair. VRID-1 is running upstream of ADX, while VRID-2 and VRID-3 are running downstream of ADX. These VRID instances are also configured to track any failure of interface ports. In addition, non-preemption is enabled on ADX-1.


Orchestrating seamless HA failover using VRRP-E pool6

In the beginning, the two systems are configured so that ADX-1 owns all the VIPs and is the master of all three VRRP-E VRID instances. A failure of the link between ADX-1 and an upstream Layer 3 router results in HA failover, and ownership of all VIPs and VRID instances is transferred to ADX-2 accordingly. Because non-preemption is configured on ADX-1, ADX-2 continues to retain ownership even after recovery of the failed link.

At this stage, both forward and reverse SLB traffic is processed by ADX-2.

If the link between ADX-2 and the upstream Layer 3 router fails, ADX-1 assumes ownership of VRID 1, while ADX-2 retains the ownership for VRID 2 and VRID 3. The forward traffic is now directed to ADX-1, while reverse traffic is directed to ADX-2. Although the traffic continues to flow uninterrupted at this stage, it is asymmetric, which may be undesirable in some installations.

The VRRP-E pool mitigates the asymmetry by grouping VRID instances and tracking their ownership states together. In Figure 48, if the VRRP-E pool is configured to include VRID 1, VRID 2, and VRID 3, then, upon link failure between ADX-2 and the upstream Layer 3 router, the ownership for all three VRID instances is switched over to ADX-1 regardless of the non-preemption setting on ADX-1. This maintains traffic symmetry.

NOTEIf a VRRP-E pool has at least one VRID enabled for non-preemption mode, then all the other VRIDs within the same pool will also assume the non-preemption mode of operation.

The VRRP-E VRID pool ensures that all instances within the pool that are in the backup state override the non-preemption setting if one of the following situations occurs:

• The unit that has high VRRP-E priority receives an advertisement with lower priority and the VRRP-E pool to which it belongs to has at least one master (similar to the interface failure scenario described previously).

• The unit receives consecutive advertisements with reducing priorities, and all the tracked ports are up.

NOTEAggregation is applicable to both track-ports and track-trunk ports and are propagated topeer VRIDs within the same pool.


Orchestrating seamless HA failover using VRRP-E pool 6

Configuring VRRP-E pools To configure a VRRP-E pool and add member VRID instances, use the following commands.

Brocade (config)# ip vrrp-extended pool 7Brocade (conf-vrrpe-pool)# vrid 3

Syntax: ip vrrp-extended pool pool-id

The pool-id variable identifies the pool with the specified ID. The ID ranges from 1 through 8.

Syntax: vrid vrid # | all

The vrid # variable identifies the specified instance. The all option adds all the configured VRIDs to the pool at once rather than one by one.

NOTEWhen the vrid all command is used, you must ensure that there is only one VRRP-E pool in the in the ServerIron ADX device.

Use the show ip vrrp-extended pool command to display VRRP-E pool details.

Brocade # show ip vrrp-extended poolTotal number of pools: 1Pool 1Mode : PreemptTracked Ports :ethernet 1

ethernet 2 ethernet 3

ethernet 4Member VRIDs : 20 [MASTER]

10 [MASTER]

Guidelines for configuring VRRP-E pools• Configure all VRID instances to track the same set of interface ports.

• If track port priority is defined, then it must be same across all VRID instances.

• If a virtual interface (VI) consists of more than one physical interface port, the VRID must track each of these physical ports individually.

• If a VRRP-E is configured on a virtual interface, you must add the virtual interface as well as the member ports as track-ports for VRRP-E pool configuration.


Maintaining traffic symmetry by adjusting OSPF cost during HA and VRRP-E switchover6

Maintaining traffic symmetry by adjusting OSPF cost during HA and VRRP-E switchover

In many HA deployments, the administrator maintains symmetry of the traffic flow by adjusting SYM priorities, VRRP-E track priorities, and routing protocol costs to favor one device over the other. During HA failover, the non-owner ServerIron ADX device takes over control of service VIPs by adjusting the SYM priority values. The VRRP-E ownerships are also shifted by adjusting the VRRP-E track priority. In addition, the ServerIron ADX device provides a mechanism to adjust OSPF cost to maintain traffic symmetry.

FIGURE 49 Adjusting OSPF cost - Sample network topology


Configuring OSPF cost adjustment during HA and VRRP-E failover 6

In the network topology shown in Figure 49, the downstream is configured with VRRP-E while the upstream is configured with OSPF. The definition of VIP groups with VRRP-E tracking is leveraged to associate VIP ownership with VRRP-E ownership. The routes for VIP subnets will be propagated by OSPF from ADX to Layer 3 router.

If the VIP Route Health Injection (VIP RHI) feature is not enabled, both the ServerIron ADX devices advertise the route for the VIP subnet through OSPF. The router upstream of the ServerIron ADX devices observe two paths to reach the VIP route and distribute the traffic between the two, breaking the overall symmetry of traffic flow.

The ServerIron ADX devices in the HA pair can be programmed to advertise a lower OSPF cost from the device that holds ownership for VIP and VRRP-E. With the OSPF cost adjustment feature enabled, the OSPF cost from the non-owner device is incremented by a preconfigured value. The upstream router thus prefers the ServerIron ADX device that owns all VIPs and VRRP-E for forwarding client traffic. During HA failover, the advertised OSPF costs are adjusted again to maintain traffic symmetry.

NOTEIf VIP Route Health Injection (VIP RHI) feature is enabled on ADX, then only the owner ServerIron ADX device advertises the VIP route. The OSPF cost adjustment in such deployments becomes unnecessary.

Configuring OSPF cost adjustment during HA and VRRP-E failover

The route map configuration has been enhanced by including the set track-vrrp-e command for tracking a VRRP-E instance. Additional VRRP-E instances may be tracked by repeating the command with a different sequence ID.

To track a VRRP-E instance, use the following command.

Brocade (conf)# set track-vrrp-e vrid 7 incremental-cost 110

Syntax: set track-vrrp-e vrid vrid incremental-cost cost

The vrid variable identifies the VRID instance. The cost variable specifies the incremental cost value and ranges from 1 through 255. The default is 200.

The OSPF cost for the advertised VIP route from the non-owner ServerIron ADX unit is increased by the value specified for cost. The OSPF cost from the owner ServerIron ADX device is not changed. The show route-map command has been enhanced to display details of the tracked VRRP-E instances.

Example:

ADX(config)#router ospfADX(config)#redistribution static route-map rm1ADX(config)#route-map rm1 permit 10ADX(config-routemap rm1)# match ip address 1ADX(config-routemap rm1)# set metric-type type-1ADX(config-routemap rm1)# set track-vrrp-e vrid 1 incremental-cost 250ADX(config)# route-map rm1 permit 20ADX(config-routemap rm1)# match ip address 2ADX(config-routemap rm1)# set metric-type type-1ADX(config-routemap rm1)# set track-vrrp-e vrid 1


Additional variations6

OSPF and route-map configurationServerIronADX 1000# configure terminalServerIronADX 1000(config)# router ospfServerIronADX 1000(config)# redistribution static route-map rm1

Configuring track VRRP-e with an incremental cost ServerIronADX 1000(config)# route-map rm1 permit 1ServerIronADX 1000(config-routemap rm1)# match ip address 2ServerIronADX 1000(config-routemap rm1)# set metric-type type-1ServerIronADX 1000(config-routemap rm1)# set track-vrrp-e vrid 1 incremental-cost 250

Configuring track VRRP-E with default incremental cost ServerIronADX 1000(config)#route-map rm1 permit 2ServerIronADX 1000(config-routemap rm1)# match ip address 4ServerIronADX 1000(config-routemap rm1)# set metric-type type-1ServerIronADX 1000(config-routemap rm1)# set track-vrrp-e vrid 1

Additional variations

Multiple high availability SLB pairs in the same VLAN

Hot Standby HA topology

Hot Standby HA redundancy enables a ServerIron ADX to serve as an automatic backup for another ServerIron ADX. Each Hot Standby HA pair consists of two ServerIron ADXs.

You can configure up to 127 Hot Standby HA pairs within a single broadcast domain in a Hot Standby HA topology. To do this, configure a backup group ID on each of the ServerIron ADXs. Both ServerIron ADXs in a given pair have the same ID. The ID uniquely identifies the pair.

When you configure a backup group ID, both ServerIron ADXs in a Hot Standby HA pair use the ID when exchanging backup information. If a ServerIron ADX receives a backup information packet but the packet's backup group ID does not match the ServerIron ADX's backup group ID, the ServerIron ADX will not process this packet for Hot Standby HA.

If the broadcast domain contains multiple Hot Standby HA pairs, you must configure backup group IDs on all pairs. If the broadcast domain contains only one Hot Standby HA pair, you do not need to configure a backup group ID.


Additional variations 6

Configuring a backup-group ID

Use the server backup-group id command to configure a backup-group ID. Enter the same ID on both ServerIron ADXs in a Hot Standby HA pair. Do not enter the same ID on a ServerIron ADX that is not one of the ServerIron ADXs in the Hot Standby HA pair. The default value is 0. This feature is turned on by default.

To configure a backup-group ID, enter the following command.

ServerIronADX(config)#server backup-group 1

Syntax: [no] server backup-group id

The id variable specifies the backup-group ID and can be a number from 0 through 7.

Use the show server backup command in a Hot Standby HA topology to display the backup ID information. If there is a group-ID mismatch, both ServerIron ADXs will become active (instead of one standby and one active).

Symmetric topology

Symmetric Active-Standby HA increases performance and simplifies a redundant topology. It provides these benefits by allowing you to implement redundancy on an individual VIP basis. Unlike a conventional Hot Standby HA configuration, you can actively use all the ServerIron ADXs in a Symmetric Active-Standby HA configuration simultaneously.

You can configure up to 255 Symmetric Active-Standby HA pairs within a single broadcast domain in a symmetric topology. To do this, configure a symmetric group ID on each of the ServerIron ADXs. Both ServerIron ADXs in a given pair must have the same ID. The ID uniquely identifies the pair.

When you configure a symmetric group ID, both ServerIron ADXs in a Symmetric Active-Standby HA pair use the ID when exchanging symmetric protocol information. If a ServerIron ADX receives a symmetric protocol information packet but the packet's symmetric group ID does not match the ServerIron ADX's symmetric group ID, the ServerIron ADX discards the packet.

If the broadcast domain contains multiple symmetric pairs, you must configure symmetric group IDs on all pairs. If the broadcast domain contains only one symmetric pair, you do not need to configure a symmetric group ID.

Configuring a symmetric group ID

To configure a symmetric group ID, enter the following command.

ServerIronADX(config)#server symmetric-group 2

Syntax: [no] server symmetric-group id

The id variable specifies the symmetric group ID and can be a number from 1 through 255. The default value is 1 and this feature is enabled by default. Enter the same ID on both ServerIron ADXs in a symmetric pair. Do not enter the same ID on a ServerIron ADX that is not one of the ServerIron ADXs in the symmetric pair.

NAT in HA environmentsThe ServerIron ADX supports NAT in high availability (HA) environments using VRRP or VRRP-E. Inside source NAT translates the private source IP address of a host into a public IP address before forwarding the host’s packet onto a public network.



VRRP and VRRP-E

NOTEServerIronADX supports VRRP-E for IPv4 and IPv6.

Virtual Router Redundancy Protocol (VRRP) and a Brocade-enhanced implementation of VRRP called VRRP Extended (VRRP-E) enable a pair of ServerIron ADXs in a high-availability configuration to provide redundant support for an IP address. If one of the ServerIron ADXs becomes unavailable, the redundant IP address continues to be available on the other ServerIron ADX. For example, you can use VRRP-E in an active-active SLB configuration to provide redundancy for a ServerIron ADX IP address used as clients or servers connected to the ServerIron ADXs as their default gateway.

You can use either VRRP or VRRP-E in your redundant configurations. The primary difference between the two protocols is that VRRP requires the backed up address to be owned by one of the devices. This means the address is physically configured on one of the interfaces used for the backed up address. VRRP-E does not have this requirement.

NOTEThe following examples assume the ServerIron ADX is in the same subnet as the source and destination address of the translated traffic.

VIP-group for NAT pools

The following commands enable the two ServerIron ADXs in a redundant configuration to negotiate the ownership of NAT pools.

Use the ip-nat-pool command to specify the NAT pool under a server VIP group.

ServerIronADX(config)#server vip-group 1ServerIronADX(config-vip-group-[1])#ip-nat-pool pool1

Once NAT pools are defined as members of a VIP group, the VIP group must be added to a VRRP-E configuration, under the VRID. It must be added to the outside interface (the interface configured with the ip nat outside command).

interface eth x/xip vrrp-extended vrid nvip-group n



Configuration example: active-active inside source NAT with VRRP-E

Figure 50 shows an example of a topology of inside source NAT configuration that also uses VRRP-E. Each ServerIron ADX is configured with the same source NAT information. In addition, each ServerIron ADX is configured as a VRRPE backup for the IP addresses of the interfaces to the routers.

FIGURE 50 Inside source NAT with VRRP-E

The ServerIron ADXs are each configured to translate the source IP addresses of clients in the private network (10.10.10.x) into IP addresses in the external network (10.10.20.x). For simplicity, this example uses another private subnet as the external subnet. However, the external IP addresses would normally be Internet addresses.

To provide additional redundancy, each ServerIron ADX is connected to the Layer 2 switches by four ports. The ports are all members of the same VLAN and share a virtual routing interface. As a result, if an individual port becomes unavailable, the link remains intact. If the entire link becomes unavailable, VRRP-E fails over to the ServerIron ADX, to maintain availability of the backed up IP address.



The IP addresses that are backup by VRRP-E are the addresses used by the hosts in the 10.10.10.x and 10.10.20.x sub-nets as their default gateways. For example, VRRP-E is configured on both ServerIron ADXs to back up IP address 10.10.20.1, which is used by the hosts in 10.10.20.x as the default gateway.

Notice that each backed-up address is configured on a virtual routing interface, which is associated with all the ports connecting the ServerIron ADX to the address’ subnet. Normally, an IP address can be associated with only one physical port. To associate the address with all the ports in the trunk group, this configuration places all the ports into a separate port-based VLAN, adds a virtual routing interface to the VLAN, then configures the backed up IP address on the virtual routing interface.

By default, the ServerIron ADX on which you configure the higher VRRP-E priority for the backed up IP address is the master for the address and handles the routing for the address. The other ServerIron ADX is a backup. If the master ServerIron ADX is unable to continue routing for the address, the backup ServerIron ADX performs the routing for the address.

ServerIron ADX-A configurationServerIronADX> enableServerIronADX#configure terminalServerIronADX(config)#hostname ServerIron ADXA

The following commands configure two virtual interfaces, for the ServerIron ADX’s interfaces with the internal and external networks. Each interface is configured on a port-based VLAN consisting of four ports. Notice that an IP address is configured on each virtual routing interface. VRRP and VRRPE require the interface on which you configure a virtual router ID (VRID) to have an IP interface that is in the same subnet as the VRID address. In this example, virtual routing interface 1 has IP address 10.10.20.1 and its VRID address (configured later in this example) is 10.10.20.10. Virtual routing interface 2 has IP address 10.10.10.1 and VRID address 10.10.10.10.

ServerIronADXA(config)#vlan 100ServerIronADXA(config-vlan-100)#untagged ethernet 1/1 to 1/4ServerIronADXA(config-vlan-100)#router-interface ve 1ServerIronADXA(config-vlan-100)#exitServerIronADXA(config)#interface ve 1ServerIronADXA(config-ve-1)#10.10.20.1 255.255.255.0ServerIronADXA(config-ve-1)# exitServerIronADXA(config)#vlan 200ServerIronADXA(config-vlan-200)#untagged ethernet 1/5 to 1/8ServerIronADXA(config-vlan-200)#router-interface ve 2ServerIronADXA(config-vlan-200)#exitServerIronADXA(config)#interface ve 2ServerIronADXA(config-ve-2)#10.10.10.1 255.255.255.0ServerIronADXA(config-ve-2)#exit

The following commands configure the source NAT parameters. The access-list command configures a standard IP ACL to identify the source IP addresses that are eligible for translation. These are the addresses of the hosts on the internal network. The ip nat pool command configures an IP address pool for use during translation. The source IP address of an internal host’s packet will be translated to one of the addresses in the pool before being forwarded to the external network. The ip nat inside source command enables inside source NAT and identifies the ACL containing the source addresses to be translated and the pool containing the translation addresses. The ip nat outside command on virtual routing interface 1 indicates that this is the NAT interface connected to the external network. Likewise, the ip nat inside command on virtual routing interface 2 indicates it is the NAT interface connected to the inside network.



ServerIronADXA(config)#access-list 1 permit 10.10.10.0 0.0.0.255ServerIronADXA(config)#ip nat pool actnat 10.10.20.10 10.10.20.20 prefix-len 24ServerIronADXA(config)#ip nat inside source list 1 pool actnatServerIronADXA(config)#interface ve 1ServerIronADXA(config-ve-1)#ip nat outsideServerIronADXA(config-ve-1)#exitServerIronADXA(config)#interface ve 2ServerIronADXA(config-ve-2)#ip nat insideServerIronADXA(config-ve-2)#exit

The following commands configure the active-active link between the ServerIron ADX devices. The port used for the link must be in its own port-based VLAN, separate from the other ports.

The server active-active-port command specifies the active-active port and the VLAN used to perform the session SYNC for the SYN-Guard and the NAT traffic.

ServerIronADXA(config)#vlan 13ServerIronADXA(config-vlan-13)#untagged ethernet 1/13ServerIronADXA(config-vlan-13)#exitServerIronADXA(config)#server active-active-port ethernet 1/13 vlan-id 13

The following commands configure the VRRP-E parameters. For each virtual routing interface, the address indicated by the ip-address command is the address that will be backed up by VRRP-E. The track-port commands identify the interfaces on the other side of the ServerIron ADX that complete the link for the VRID. For example, traffic that is addressed to VRID 1 enters the ServerIron ADX through virtual routing interface 1 and leaves the ServerIron ADX through virtual routing interface 2. Normally, if virtual routing interface 2 goes down, VRID 1 remains active. When you track interfaces for a VRID, if the state of one of the tracked interfaces changes, the software associates the change with the VRID interface. For example, if virtual routing interface 2 goes down, the software associates this state change with VRID 1 and causes VRRP-E to fail over the VRID to the other ServerIron ADX. For each virtual routing interface, the track-port commands in this example configure the other virtual routing interface and all the physical ports in the VLAN on which the other virtual routing interface is configured as track ports.

ServerIronADXA(config)#router vrrp-extendedServerIronADXA(config)#interface ve 1ServerIronADXA(config-ve-1)#ip vrrp-extended vrid 1ServerIronADXA(config-ve-1-vrid-1)#backupServerIronADXA(config-ve-1-vrid-1)#ip-address 10.10.20.10ServerIronADXA(config-ve-1-vrid-1)#enableServerIronADXA(config-ve-1-vrid-1)#track-port ethernet 1/5ServerIronADXA(config-ve-1-vrid-1)#track-port ethernet 1/6ServerIronADXA(config-ve-1-vrid-1)#track-port ethernet 1/7ServerIronADXA(config-ve-1-vrid-1)#track-port ethernet 1/8ServerIronADXA(config-ve-1-vrid-1)#track-port ethernet ve 2ServerIronADXA(config-ve-1-vrid-1)#exitServerIronADXA(config-ve-1)#exitServerIronADXA(config)#interface ve 2ServerIronADXA(config-ve-2)#ip vrrp-extended vrid 2ServerIronADXA(config-ve-2-vrid-2)#backupServerIronADXA(config-ve-2-vrid-2)#ip-address 10.10.10.10ServerIronADXA(config-ve-2-vrid-2)#enableServerIronADXA(config-ve-2-vrid-2)#track-port ethernet 1/1ServerIronADXA(config-ve-2-vrid-2)#track-port ethernet 1/2ServerIronADXA(config-ve-2-vrid-2)#track-port ethernet 1/3ServerIronADXA(config-ve-2-vrid-2)#track-port ethernet 1/4ServerIronADXA(config-ve-2-vrid-2)#track-port ethernet ve 1ServerIronADXA(config-ve-2-vrid-2)#exitServerIronADXA(config-ve-2)#exit



ServerIron ADX-B configurationThe following commands configure ServerIron ADX-B. Notice the NAT and VRRP-E configurations are the same as the ones on ServerIron ADX-A.

ServerIronADX#configure terminalServerIronADX(config)#hostname ServerIronADXBServerIronADXB(config)#vlan 100ServerIronADXB(config-vlan-100)#untagged ethernet 1/1 to 1/4ServerIronADXB(config-vlan-100)#router-interface ve 1ServerIronADXB(config-vlan-100)#exitServerIronADXB(config)#interface ve 1ServerIronADXB(config-ve-1)#10.10.20.3 255.255.255.0ServerIronADXB(config-ve-1)#exitServerIronADXB(config)#vlan 200ServerIronADXB(config-vlan-200)#untagged ethernet 1/5 to 1/8ServerIronADXB(config-vlan-200)#router-interface ve 2ServerIronADXB(config-vlan-200)#exitServerIronADXB(config)#interface ve 2ServerIronADXB(config-ve-2)#10.10.10.3 255.255.255.0ServerIronADXB(config-ve-2)#exitServerIronADXB(config)#access-list 1 permit 10.10.10.0 0.0.0.255ServerIronADXB(config)#ip nat pool actnat 10.10.20.10 10.10.20.20 prefix-len 24ServerIronADXB(config)#ip nat inside source list 1 pool actnatServerIronADXB(config)#interface ve 1ServerIronADXB(config-ve-1)#ip nat outsideServerIronADXB(config-ve-1)#exitServerIronADXB(config)#interface ve 2ServerIronADXB(config-ve-2)#ip nat insideServerIronADXB(config-ve-2)#exitServerIronADXB(config)#vlan 13ServerIronADXB(config-vlan-13)#untagged ethernet 1/13ServerIronADXB(config-vlan-13)#exitServerIronADXB(config)#server active-active-port ethernet 1/13 vlan-id 13ServerIronADXB(config)#router vrrp-extendedServerIronADXB(config)#interface ve 1ServerIronADXB(config-ve-1)#ip vrrp-extended vrid 1ServerIronADXB(config-ve-1-vrid-1)#backupServerIronADXB(config-ve-1-vrid-1)#ip-address 10.10.20.10ServerIronADXB(config-ve-1-vrid-1)#enableServerIronADXB(config-ve-1-vrid-1)#track-port ethernet 1/5ServerIronADXB(config-ve-1-vrid-1)#track-port ethernet 1/6ServerIronADXB(config-ve-1-vrid-1)#track-port ethernet 1/7ServerIronADXB(config-ve-1-vrid-1)#track-port ethernet 1/8ServerIronADXB(config-ve-1-vrid-1)#track-port ethernet ve 2ServerIronADXB(config-ve-1-vrid-1)#exitServerIronADXB(config-ve-1)#exitServerIronADXB(config)#interface ve 2ServerIronADXB(config-ve-2)#ip vrrp-extended vrid 2ServerIronADXB(config-ve-2-vrid-2)#backupServerIronADXB(config-ve-2-vrid-2)#ip-address 10.10.10.10ServerIronADXB(config-ve-2-vrid-2)#enableServerIronADXB(config-ve-2-vrid-2)#track-port ethernet 1/1ServerIronADXB(config-ve-2-vrid-2)#track-port ethernet 1/2ServerIronADXB(config-ve-2-vrid-2)#track-port ethernet 1/3ServerIronADXB(config-ve-2-vrid-2)#track-port ethernet 1/4ServerIronADXB(config-ve-2-vrid-2)#track-port ethernet ve 1ServerIronADXB(config-ve-2-vrid-2)#exit



IP NAT session synchronization in HA configurationsIP NAT sessions created by the active ServerIron ADX in an Symmetric Active-Standby HA configuration are synchronized to the standby ServerIron ADX. When failover occurs, the standby ServerIron ADX will be able to use the IP NAT session information created by the active ServerIron ADX.

IP NAT session synchronization is performed automatically. No configuration is necessary.

Shareable source NAT for high availabilityYou can configure both peer ServerIron ADXs in a high-availability configuration to share the same source NAT IP address. In addition, the source NAT sessions are synchronized between the peers. Shareable source NAT IP addresses were supported only for Hot Standby HA configurations, and source NAT sessions were not synchronized.

In a high-availability configuration, an address configured as a source IP address serves the following purposes:

• It provides the real servers with a default gateway address.

• The ServerIron ADX uses the address for source NAT. To keep track of the flows for which source NAT has been performed, the ServerIron ADX allocates a “port” to each flow. For each source IP address, up to 54,000 ports can be allocated to flows.

In a Hot Standby HA configuration, the active ServerIron ADX “owned” the source NAT IP address, responding to ARP requests and performing source NAT with the configured source IP address. When failover occurred, the standby ServerIron ADX, also configured with the same source NAT IP address, took over these duties. However, the source NAT sessions were not synchronized between the peers.

In a Symmetric Active-Standby HA configuration, where both peer ServerIron ADXs are active for the same application port and VIP at the same time, it was not possible for both peer ServerIron ADXs to perform source NAT using the same source IP address, because a conflict could occur if both ServerIron ADXs allocated the same port to different flows.

You can divide the ports used for source NAT for a given source IP address into two equal groups, or port ranges. One peer controls the “lower” port range, and the other peer controls the “upper” port range. When performing source NAT, each peer allocates ports belonging only to its port range, thus avoiding port conflicts.

In Symmetric Active-Standby HA configurations, ownership of the source IP address is based on the port range. The peer controlling the upper port range for the source IP address is the owner of the address and responds to ARP requests. If the owner of the source IP address fails, the peer takes over ownership of the source IP address. When this feature is enabled, the two ServerIron ADXs report and receive the ownership of the source IP address using a variation of the Symmetric Active-Standby HA protocol. When the ports used for source NAT for a given source IP address are divided in this way, it allows the same source IP address to be configured on both peers in all supported high-availability configurations, including Symmetric Active-Standby HA and Symmetric Active-Active HA.

In Hot Standby HA configurations, the active ServerIron ADX is the owner of the source IP address. However, you must still define each ServerIron ADX’s port range in order to prevent port conflicts between different flows.



NOTEThe ServerIron ADX does not support Symmetric Active-Standby HA with shared source NAT IPs. The reason is because the VIP and the source IP may not be active on the same ServerIron ADX, and as a result, the ServerIron ADX will not know how to forward return traffic. Configure Symmetric Active-Active HA as a workaround.

Router configuration example

Figure 51 illustrates a sample Symmetric Active-Active HA configuration that uses shared source IP addresses.

FIGURE 51 Sample Symmetric Active-Active HA configuration using shared source IP addresses

ServerIron ADX-A configuration

The following commands configure ServerIron ADX-A in Figure 51.

ServerIronADX-A(config)#ip address 10.10.1.1 255.255.0.0ServerIronADX-A(config)#ip default-gateway 10.10.1.254

ServerIronADX-A(config)#server port 80ServerIronADX-A(config-port-http)#session-syncServerIronADX-A(config-port-http)#tcpServerIronADX-A(config-port-http)#exit

ServerIronADX-A(config)#server port 21ServerIronADX-A(config-port-ftp)#session-syncServerIronADX-A(config-port-ftp)#exit

ServerIronADX-A(config)#server port 23ServerIronADX-A(config-port-telnet)#session-syncServerIronADX-A(config-port-telnet)#exit



ServerIronADX-A(config)#server source-nat-ip 10.10.1.10 255.255.0.0 0.0.0.0 port-ra 1ServerIronADX-A(config)#server source-nat-ip 10.10.1.11 255.255.0.0 0.0.0.0 port-ra 1ServerIronADX-A(config)#server source-nat-ip 10.10.1.12 255.255.0.0 0.0.0.0 port-ra 1

ServerIronADX-A(config)#server router-ports ethernet 3/1

ServerIronADX-A(config)#server real rs1 10.10.1.30ServerIronADX-A(config-rs-rs1)#port httpServerIronADX-A(config-rs-rs1)#port http url "HEAD /"ServerIronADX-A(config-rs-rs1)#port ftpServerIronADX-A(config-rs-rs1)#port rtspServerIronADX-A(config-rs-rs1)#port telnetServerIronADX-A(config-rs-rs1)#exit

ServerIronADX-A(config)#server real rs2 10.10.1.31ServerIronADX-A(config-rs-rs2)#port httpServerIronADX-A(config-rs-rs2)#port http url "HEAD /"ServerIronADX-A(config-rs-rs2)#port ftpServerIronADX-A(config-rs-rs2)#port rtspServerIronADX-A(config-rs-rs2)#port telnetServerIronADX-A(config-rs-rs2)#exit

ServerIronADX-A(config)#server real rs3 10.10.2.30ServerIronADX-A(config-rs-rs3)#port httpServerIronADX-A(config-rs-rs3)#port http url "HEAD /"ServerIronADX-A(config-rs-rs3)#port ftpServerIronADX-A(config-rs-rs3)#port telnetServerIronADX-A(config-rs-rs3)#exit

ServerIronADX-A(config)#server real rs4 10.10.2.31ServerIronADX-A(config-rs-rs4)#port httpServerIronADX-A(config-rs-rs4)#port http url "HEAD /"ServerIronADX-A(config-rs-rs4)#port ftpServerIronADX-A(config-rs-rs4)#port telnetServerIronADX-A(config-rs-rs4)#exit

ServerIronADX-A(config)#server virtual-name-or-ip test 10.10.1.100ServerIronADX-A(config-vs-test)#sym-priority 200ServerIronADX-A(config-vs-test)#sym-activeServerIronADX-A(config-vs-test)#port httpServerIronADX-A(config-vs-test)#port ftpServerIronADX-A(config-vs-test)#port telnetServerIronADX-A(config-vs-test)#bind http rs1 http rs2 http rs3 http rs4 httpServerIronADX-A(config-vs-test)#bind ftp rs1 ftp rs2 ftp rs3 ftp rs4 ftpServerIronADX-A(config-vs-test)#bind telnet rs1 telnet rs2 telnet rs3 telnet rs4 telnetServerIronADX-A(config-vs-test)#exit



ServerIron ADX-B configuration

The following commands configure ServerIron ADX-B in Figure 51. The commands are identical to those for ServerIron ADX-A except for the ServerIron ADX’s IP address.

ServerIronADX-B(config)#ip address 10.10.1.2 255.255.0.0ServerIronADX-B(config)#ip default-gateway 10.10.1.254

ServerIronADX-B(config)#server port 80ServerIronADX-B(config-port-http)#session-syncServerIronADX-B(config-port-http)#tcpServerIronADX-B(config-port-http)#exit

ServerIronADX-B(config)#server port 21ServerIronADX-B(config-port-ftp)#session-syncServerIronADX-B(config-port-ftp)#exit

ServerIronADX-B(config)#server port 23ServerIronADX-B(config-port-telnet)#session-syncServerIronADX-B(config-port-telnet)#exit

ServerIronADX-B(config)#server source-nat-ip 10.10.1.10 255.255.0.0 0.0.0.0 port-ra 2ServerIronADX-B(config)#server source-nat-ip 10.10.1.11 255.255.0.0 0.0.0.0 port-ra 2ServerIronADX-B(config)#server source-nat-ip 10.10.1.12 255.255.0.0 0.0.0.0 port-ra 2 ServerIronADX-B(config)#server router-ports ethernet 3/1

ServerIronADX-B(config)#server real rs1 10.10.1.30ServerIronADX-B(config-rs-rs1)#port httpServerIronADX-B(config-rs-rs1)#port http url "HEAD /"ServerIronADX-B(config-rs-rs1)#port ftpServerIronADX-B(config-rs-rs1)#port rtspServerIronADX-B(config-rs-rs1)#port telnetServerIronADX-B(config-rs-rs1)#exit

ServerIronADX-B(config)#server real rs2 10.10.1.31ServerIronADX-B(config-rs-rs2)#port httpServerIronADX-B(config-rs-rs2)#port http url "HEAD /"ServerIronADX-B(config-rs-rs2)#port ftpServerIronADX-B(config-rs-rs2)#port rtspServerIronADX-B(config-rs-rs2)#port telnetServerIronADX-B(config-rs-rs2)#exit

ServerIronADX-B(config)#server real rs3 10.10.2.30ServerIronADX-B(config-rs-rs3)#port httpServerIronADX-B(config-rs-rs3)#port http url "HEAD /"ServerIronADX-B(config-rs-rs3)#port ftpServerIronADX-B(config-rs-rs3)#port telnetServerIronADX-B(config-rs-rs3)#exit

ServerIronADX-B(config)#server real rs4 10.10.2.31ServerIronADX-B(config-rs-rs4)#port httpServerIronADX-B(config-rs-rs4)#port http url "HEAD /"ServerIronADX-B(config-rs-rs4)#port ftpServerIronADX-B(config-rs-rs4)#port telnetServerIronADX-B(config-rs-rs4)#exit

ServerIronADX-B(config)#server virtual-name-or-ip test 10.10.1.100



ServerIronADX-B(config-vs-test)#sym-priority 100ServerIronADX-B(config-vs-test)#sym-activeServerIronADX-B(config-vs-test)#port httpServerIronADX-B(config-vs-test)#port ftpServerIronADX-B(config-vs-test)#port telnetServerIronADX-B(config-vs-test)#bind http rs1 http rs2 http rs3 http rs4 httpServerIronADX-B(config-vs-test)#bind ftp rs1 ftp rs2 ftp rs3 ftp rs4 ftpServerIronADX-B(config-vs-test)#bind telnet rs1 telnet rs2 telnet rs3 telnet rs4 telnetServerIronADX-B(config-vs-test)#exit

Enabling VRRP and binding a VIP group to a virtual router ID

To enable VRRP and bind a VIP group to a Virtual Router ID (VRID), enter commands such as the following.

ServerIronADX(config)#router vrrpServerIronADX(config)#interface e 1/2ServerIronADX(config-if-e100-1/2)#ip vrrp vrid 1ServerIronADX(config-if-e100-12-vrid-1)#vip-group 1

Syntax: [no] router vrrp | vrrp-extended

Syntax: [no] ip vrrp vrid vrid number

Syntax: [no] vip-group number

The number variable is the VIP group number (from 1 through 10) that you are binding to the VRID. Note that each VIP group can have only one VRID associated with it.

Each virtual IP address can belong to only one VIP group. Also, each VIP group can have only one VRID associated with it.

Use these commands with the server vip-group command to guarantee simultaneous VIP failover in the event VRRP-E fails over to a Backup router.

IP NAT session synchronization in high-availability configurations

IP NAT sessions created by the active ServerIron ADX in an Symmetric Active-Standby HA configuration are synchronized to the standby ServerIron ADX. When failover occurs, the standby ServerIron ADX will be able to use the IP NAT session information created by the active ServerIron ADX.

IP NAT session synchronization is performed automatically. No configuration is necessary.

Shareable source NAT for high availability

You can configure both peer ServerIron ADXs in a high-availability configuration to share the same source NAT IP address. In addition, the source NAT sessions are synchronized between the peers. Shareable source NAT IP addresses were supported only for Hot Standby HA configurations, and source NAT sessions were not synchronized.



In a high-availability configuration, an address configured as a source IP address serves the following purposes:

• It provides the real servers with a default gateway address.

• The ServerIron ADX uses the address for source NAT. To keep track of the flows for which source NAT has been performed, the ServerIron ADX allocates a “port” to each flow. For each source IP address, up to 54,000 ports can be allocated to flows.

In a Hot Standby HA configuration, the active ServerIron ADX “owned” the source NAT IP address, responding to ARP requests and performing source NAT with the configured source IP address. When failover occurred, the standby ServerIron ADX, also configured with the same source NAT IP address, took over these duties. However, the source NAT sessions were not synchronized between the peers.

In a Symmetric Active-Active HA configuration, where both peer ServerIron ADXs are active for the same application port and VIP at the same time, it was not possible for both peer ServerIron ADXs to perform source NAT using the same source IP address, because a conflict could occur if both ServerIron ADXs allocated the same port to different flows.

You can divide the ports used for source NAT for a given source IP address into two equal groups, or port ranges. One peer controls the “lower” port range, and the other peer controls the “upper” port range. When performing source NAT, each peer allocates ports belonging only to its port range, thus avoiding port conflicts.

In Symmetric Active-Standby HA configurations, ownership of the source IP address is based on the port range. The peer controlling the upper port range for the source IP address is the owner of the address and responds to ARP requests. If the owner of the source IP address fails, the peer takes over ownership of the source IP address. When this feature is enabled, the two ServerIron ADXs report and receive the ownership of the source IP address using a variation of the Symmetric Active-Standby HA protocol. When the ports used for source NAT for a given source IP address are divided in this way, it allows the same source IP address to be configured on both peers in all supported high-availability configurations, including Symmetric Active-Standby HA and Symmetric Active-Active HA.

In Hot Standby HA configurations, the active ServerIron ADX is the owner of the source IP address. However, you must still define each ServerIron ADX’s port range in order to prevent port conflicts between different flows.

NOTEThe ServerIron ADX does not support Symmetric Active-Standby HA with shared source NAT IPs. The reason is because the VIP and the source IP may not be active on the same ServerIron ADX, and as a result, the ServerIron ADX will not know how to forward return traffic. Configure Symmetric Active-Active HA as a workaround.

Configuring server accelerated-fin-sync commandIn an HA setup, the ServerIron ADX that created a new connection will synchronize the connection information to the partner ServerIron ADX. For a TCP connection, the synchronization message to create a session is sent when the client SYN is received (and a server is selected). During the connection, the messages are sent periodically across both the partnered ServerIron ADX. Both ServerIron ADX will age the session independently. When both FINs are received, the session is placed in delete-queue to be purged after 8 seconds (or the configured server msl command). By default, there is no sync message here. Once the session is purged from delete-queue, a sync



message is sent to remove the session from the other ServerIron ADX. This default behavior of the ServerIron ADX might result in displaying different server usage statistics on both ServerIron ADXs, or may result in the rejection of new connections on the new Active ServerIron ADX after a failover for a brief amount of time if clients reuse TCP source ports.

With the server accelerated-fin-sync command, if configured, results in a sync message for the second FIN so that the partner ServerIron ADX can put the session in delete-queue right away to be purged after 8 seconds (or the configured server msl command).

Configuring synchronization with HAThe config-sync command is explained in the "Initiating the Synchronization" section of the "ServerIron System Management" chapter in the ServerIron ADX Administration Guide.

Miscellaneous options

Displaying VIP owner in HA setupThe show server bind command display the "owner" for active VIP in HA configuration.

NOTEThis command shows the Owner for sym_state=5, non-Owner for sym_state=3, or nothing for others.

ServerIronADX#show server bind


Identifying the ports attached to a routerIf the ServerIron ADX is attached to multiple routers or to a single router configured for VRRP, FSRP, or HSRP, you need to identify the ports on the ServerIron ADX that are attached to the router. Explicitly identifying the ports enables the ServerIron ADX or switch to handle Layer 4 traffic correctly.

To identify port 8 as a router port, enter the following command.

ServerIronADX(config)#server router-port 8

Syntax: [no] server router-port portnum

To define multiple router ports on a switch, enter the port numbers, separated by blanks. You can enter up to eight router ports in a single command line. To enter more than 8 ports, enter the server router-port command again with the additional ports.

Setting VIP failback delayWhen a primary ServerIron ADX reloads and it boots up, even when all services are up and the health checks are fine, you may need an additional delay for the VIP to take traffic. Setting a VIP failback delay ensures that the standby ServerIron ADX continues taking traffic until the primary ServerIron ADX is ready to take over.



To set the VIP failback delay, enter the following command in global configuration mode.

ServerIronADX(config)#server vip-failback-delay 10

Syntax: [no] server vip-failback-delay value

The value variable is the delay in seconds. Enter an integer from 1 to 255.

NOTEThe server vip-failback-delay command is only applied in router code.



Chapter

7
IPv6 Support for Server Load Balancing
OverviewThe commands to configure server load balancing, including configuration of virtual servers, real servers, VIP groups, health check parameters, and others are the same for IPv6 as they are for IPv4. The existing commands have been enhanced to accept either IPv6 or IPv4 addresses. Other than IPv6 addressing, no new commands are necessary for configuring SLB for IPv6 on the ServerIron.

The following sections shows the configuration steps for an IPv6 SLB configuration.

1. Defining IPv6 real servers.

2. Defining IPv6 virtual servers.

3. Defining IPv4 real servers.

4. Defining IPv4 virtual servers.

5. Define port characteristics using port profile.

6. Define IP routes.

7. VLAN, tagging and trunk definitions.

8. VRRP-E and VIP group definitions.

9. Miscellaneous.

10. Saving the configuration.

Defining IPv6 real serversServerIronADX(config)#server real rs3 2001:db8::aServerIronADX(config-rs-rs3)#port httpServerIronADX(config-rs-rs3)#port httpServerIronADX(config-rs-rs3)#port http url "HEAD /"ServerIronADX(config-rs-rs3)#port dnsServerIronADX(config-rs-rs3)#exit

ServerIronADX(config)#server real rs4 2001:db8::5ServerIronADX(config-rs-rs4)#port httpServerIronADX(config-rs-rs4)#port httpServerIronADX(config-rs-rs4)#port http url "HEAD /"ServerIronADX(config-rs-rs4)#port dnsServerIronADX(config-rs-rs4)#exit

441

Defining IPv6 virtual servers7

Defining IPv6 virtual serversServerIronADX(config)#server virtual vs2 2001:db8::faceServerIronADX(config-rs-v45)#port httpServerIronADX(config-rs-v45)#port dnsServerIronADX(config-rs-v45)#bind http rs3 http rs4 http ServerIronADX(config-rs-v45)#bind http rs7 httpServerIronADX(config-rs-v45)#bind dns rs5 dns rs6 dns rs7 dns rs3 dnsServerIronADX(config-rs-v45)#bind dns rs4 dnsServerIronADX(config-rs-v45)#exit

Defining IPv4 real serversServerIronADX(config)#server real v41 10.31.31.10ServerIronADX(config-rs-v41)#port httpServerIronADX(config-rs-v41)#port http url "HEAD /"ServerIronADX(config-rs-v41)#exitServerIronADX(config)#server real v42 10.31.31.11ServerIronADX(config-rs-v42)#port httpServerIronADX(config-rs-v42)#port http url "HEAD /"ServerIronADX(config-rs-v42)#exit

Defining IPv4 virtual serversServerIronADX(config)#server virtual-name-or-ip v4-v 10.31.31.250ServerIronADX(config-vs-v4-v)#sym-priority 200ServerIronADX(config-vs-v4-v)#sym-activeServerIronADX(config-vs-v4-v)#port httpServerIronADX(config-vs-v4-v)#bind http v41 http v42 http v43 http v45 httpServerIronADX(config-vs-v4-v)#exit

Defining port characteristics using port profileServerIronADX(config)#server port 80ServerIronADX(config-port-http)#session-syncServerIronADX(config-port-http)#tcpServerIronADX(config)#exit

ServerIronADX(config)server port 53ServerIronADX(config-port-dns)#session-syncServerIronADX(config-port-dns)#tcp keepalive disableServerIronADX(config-port-dns)#udpServerIronADX(config)#exit

Defining IP routesServerIronADX(config)#ip route 0.0.0.0 0.0.0.0 10.40.40.5ServerIronADX(config)#ipv6 route 2001:db8::/64 2001:db8::212:f2ff:fea8:1400ServerIronADX(config)#exit


VLAN, tagging and trunk definitions 7

VLAN, tagging and trunk definitionsServerIronADX(config)#vlan 1 name DEFAULT-VLAN by portServerIronADX(config-vlan-1)#exit

ServerIronADX(config)#vlan 110 by portServerIronADX(config-vlan-10)#tagged ethe 3/3 to 3/4ServerIronADX(config-vlan-10)#untagged ethe 3/7ServerIronADX(config-vlan-10)#router-interface ve 10ServerIronADX(config-vlan-10)#spanning-treeServerIronADX(config-vlan-10)#exit

ServerIronADX(config)#trunk switch ethe 3/3 to 3/4ServerIronADX(config)#exit

VRRP-E and VIP group definitionsServerIronADX(config)#interface ethernet 3/1ServerIronADX(config-if-3/1)#ip address 10.40.40.1 255.255.255.0ServerIronADX(config-if-3/1)#ipv6 address 2001:db8::/64 eui-64

ServerIronADX(config)#interface ve 10ServerIronADX(config-ve-10)#ip address 10.31.31.1 255.255.255.0ServerIronADX(config-ve-10)#ipv6 address 2001:db8::/64 eui-64

ServerIronADX(config)#router vrrp-extendedServerIronADX(config)#router vrrp-extended-ipv6

ServerIronADX(config)#server vip-group 1ServerIronADX(config-vip-group-[1])#vip 2001:db8::faceServerIronADX(config-vip-group-[1])#vip 10.31.31.250ServerIronADX(config-vip-group-[1])#exit

ServerIronADX(config-ve-10)#ipv6 vrrp-extended vrid 1ServerIronADX(config-ve-10-vrid-1)#backupServerIronADX(config-ve-10-vrid-1)#ip address 2001:db8:fe80::35ServerIronADX(config-ve-10-vrid-1)#track-port e 3/1 priority 15ServerIronADX(config-ve-10-vrid-1)#enableServerIronADX(config-ve-10-vrid-1)#exitServerIronADX(config-ve-10)#exit

ServerIronADX(config-if-3/1)#ipv6 vrrp-extended vrid 4ServerIronADX(config-if-3/1-vrid-5)#backupServerIronADX(config-if-3/1-vrid-5)#ip address 2001:db8:fe80::36ServerIronADX(config-if-3/1-vrid-5)#vip-group 1ServerIronADX(config-if-3/1-vrid-5)#enableServerIronADX(config-if-3/1-vrid-5)#exitServerIronADX(config-if-3/1)#exit

ServerIronADX(config-ve-10)#ip vrrp-extended vrid 3ServerIronADX(config-ve-10-vrid-3)#backupServerIronADX(config-ve-10-vrid-3)#ip-address 10.31.31.3ServerIronADX(config-ve-10-vrid-3)#track-port e 3/1 priority 15ServerIronADX(config-ve-10-vrid-3)#enableServerIronADX(config-ve-10-vrid-3)#exit


Miscellaneous7

ServerIronADX(config-if-3/1)#ip vrrp-extended vrid 5ServerIronADX(config-if-3/1-vrid-5)#backupServerIronADX(config-if-3/1-vrid-5)#ip-address 10.40.40.3ServerIronADX(config-if-3/1-vrid-5)#enableServerIronADX(config-if-3/1-vrid-5)#exit

MiscellaneousServerIronADX(config)#aaa authentication web-server default localServerIronADX(config)#no enable aaa consoleServerIronADX(config)#exitServerIronADX(config)#telnet serverServerIronADX(config)#username admin password .....ServerIronADX(config)#snmp-server

Saving the configurationServerIronADX(config)#write memory

The IPv6 and IPv4 service definitions can co-exist on the same system.You can define IPv4 VIPs with IPv4 real servers and IPv6 VIPs with IPv6 real servers on the same system.

IPv6 to IPv4 gatewayThe ServerIron ADX allows an IPv6 client to send and receive packets to and from any of the following real servers:

• An IPv6 real server


• A combination of IPv4 and IPv6 real servers


IPv6 to IPv4 gateway 7

These configurations are shown in Figure 52.

FIGURE 52 IPv6 Client access

Access from the IPv6 client to an IPv6 real server is straight forward and doesn’t require any special processing from the ServerIron ADX. For an IPv6 client to access an IPv4 server however requires intervention from the ServerIron ADX as shown in Figure 53.

FIGURE 53 IPv6 client to IPv4 server access

As shown in this example, the IPv6 client sends its request to the ServerIron ADX with it’s own IPv6 address as the source address. The destination address is an IPv6 address assigned in the VIP configuration of the ServerIron ADX. Layer 4 - 7 processing is then applied to the packets. After processing, IP source NAT is used to exchange the source and destination IPv6 addresses for IPv4 addresses configured for the ServerIron ADX. The packets are then forwarded to the IPv4 server.


IPv6 to IPv4 gateway7

The packet flow of how the IPv4 server replies to the IPv6 is shown in Figure 54. In this example, the IPv4 server sends its IPv4 address as the source address and the destination address is the IPv4 address specified in the IP NAT configuration for the VIP. IP source NAT is used to exchange the source and destination IPv4 addresses for the IPv6 source address configured for the VIP and the destination address of the IPv6 client.

FIGURE 54 IPv4 server to IPv6 packet flow reply

Features not supported with the IPv6 to IPv4 gateway• NAT

• TRL

• VIP Protection

• Client-subnet-sticky

• Client-subnet base source-nat

• Real server hardware DSR

• Rule-based ACLv6 (only flow-based ACLs are supported)

• Source-nat ACLs

• Full-stack applications (SSL termination, etc.)

• FTP and other complex protocols

Packet fragmentation with the IPv6 to IPv4 gateway Reverse packets from the IPv4 server to the IPv6 client can be too large and need to be split into two IPv6 packets. The following describes the criteria for judging that packets are too large:

Regular packets – IP total length greater than 1480 bytes

Fragmented packets – IP total length greater than 1480 + 8 bytes

If the packets exceed these limitations, one of the following actions will be taken:

1. If the frag-664-reverse-full-sized-pkt command is configured, the packet will be split and no further actions will be performed.

2. If the condition in step 1 isn’t met, and the DF bit is set at the server, the “fragment needed” ICMP error message will be sent.

3. If the conditions in steps 1 and 2 aren’t met, the packet will be split.

The frag-664-reverse-full-sized-pkt command is configured as shown in the following.

ServerIronADX(config)#frag-664-reverse-full-sized-pkt



Syntax: [no] frag-664-reverse-full-sized-pkt

ICMP packet processing for the IPv6 to IPv4 gateway Because the client is running IPv6 and the real server is running IPv4, ICMPv6 and ICMP error messages must be processed as described in the following:

• ICMPv6 error messages from the client side are translated to ICMP messages and sent to the server

• ICMP error messages from the server are translated to ICMPv6 messages and sent to the client

• ICMP and ICMPv6 echo request messages are processed by the management module (MP)

Client side ICMP packet translation

ICMPv6 error messages are translated to equivalent ICMP error messages as shown in Table 42.

TABLE 42 ICMPv6 to ICMP error message translation

ICMPv6 error message type ICMP error message type

Destination Unreachable (Type 1) Destination Unreachable (Type 3)

* no route (code 0) * host Unreachable (code 1)

* admin prohibited (code 1) * admin prohibited (code 10)

* not neighbor (code 2) * route fail (code 5)

* address unreachable (code 3) * host unreachable (code 1)

* port unreachable (code 4) * port unreachable (code 3)

Packet Too Big (Type 2) Destination Unreachable (Type 3)* fragment needed (code 4)

Time Exceeded (Type 3) Time exceeded (Type 11)* code remains the same from ICMPv6

Parameter Problem (Type 4)

* next header Type – Dest Unreachablecode – protocol unreachable

* any other param problem Type – param probcode – 0



Server side ICMP packet translation


IPv6 to IPv4 gateway high availability supportHot standby, Symmetric Active-Standby, and Symmetric Active-Active HA configurations are supported for the IPv6 to IPv4 gateway with the following considerations:

• The format for all HA messages that do not contain IP address remain the same for IPv4 and IPv6 (for example, hot-standby heart beat).

• Session synchronization messages (which contain IP addresses) send IPv6 addresses for the forward sessions and IPv4 addresses for the reverse sessions for IPv6 traffic.


ICMP error message type ICMPv6 error message type


* net unreachable (code 0) * no route code (code 0)

* host unreachable (code 1) * no route code (code 0)

* protocol unreachable (code 2) * type – param prob, code – 0

* port unreachable (code 3) * no port (code 4)

* fragment needed (code 4) * type – packet too big, code – no route

* route fail (code 0) * not neighbor code (code 1)

* unknown dest network (code 1) * no route code (code 0)

* unknown dest host (code 2) * no route code (code 0)

* source host isolated (code 3) * no route code (code 0)

* dest network admin prohibited (code 4)

* admin prohibited (code 1)

* dest host admin prohibited (code 0 * admin prohibited (code 1)

* network unreachable for tos (code 1) * no route code (code 0)

* host unreachable for tos (code 2) * no route code (code 0)

* admin prohibit (code 3) * admin prohibited (code 1)

* host precedence violated (code 4) * admin prohibited (code 1)

* precedence cutoff in effect (code 4) * admin prohibited (code 1)

Time Exceeded (Type 3) Time exceeded (Type 11)* code remains the same from ICMPv6

Parameter Problem (Type 4)

* next header

* any other param problem

Type – Dest Unreachablecode – protocol unreachable

Type – param probcode – 0



Configuring the IPv6 to IPv4 gatewayAlthough the IPv6 to IPv4 gateway doesn’t require any special commands, you must perform the following configurations:

• Enable Source NAT (either globally or on the IPv4 real servers)

• Configure IPv4 Source NAT IP address

• Configure an IPv4 real server

• Configure an IPv6 VIP


The following example provides a sample configuration for the ServerIron ADX in Figure 53 and Figure 54.

The following commands enable Source NAT globally and configure an IPv4 Source NAT IP address.

ServerIronADX(config)#server source-natServerIronADX(config)#server source-nat-ip 10.130.130.5 255.255.255.0 0.0.0.0 port-range 2

The following commands configure an IPv4 real server.

ServerIronADX(config)#server real rs1 10.130.130.1ServerIronADX(config-rs-rs1)#port httpServerIronADX(config-rs-rs1)#exit

The following commands configure an IPv6 VIP.

ServerIronADX(config)#server virtual-name-or-ip vip664 2001:db8:30::1ServerIronADX(config-vs-vip664)#port httpServerIronADX(config-vs-vip664)#bind http rs1 httpServerIronADX(config-vs-vip664)#exit



Displaying IPv6 to IPv4 gateway informationYou can use the show session all and show ipv6 map-statistics commands to display information about an IPv6 to IPv4 gateway.

The show session all command displays sessions created for the IPv6 to IPv4 gateway traffic. The forward sessions has IPv6 addresses and the reverse sessions have IPv4 addresses.

In this example the IPv6 to IPv4 gateway configuration has the following IPv4 and IPv6 addresses:

• IPv6 Client IP address: 2001:db8::1

• IPv6 VIP: 2001:db8::4

• IPv4 Server IP: 10:30:30:1

• IPv4 Source NAT IP: 10.30.30.5

ServerIronADX#rconsole 1 1ServerIronADX1/1#show session all 0Session Info:Flags - 0:UDP, 1:TCP, 2:IP, 3:INT, 4:INVD, H: sessInHash, N: sessInNextEntry

Index Src-IP Dst-IP S-port D-port Age Server Flags==========================================================================0 2001:db8::1 2001:db8::4 53421 80 34 rs1-ipv4 SLB1 H 1 10.30.30.1 10.30.30.5 80 17430 34 rs1-ipv4 SLB1 H

The show ipv6 map-statistics command displays the number of client and real server packets. The following example displays memory mapping statistics for an IPv6 to IPv4 gateway (IPv6-6-4) forward (Client packets) and reverse (real server packets).

ServerIronADX#rconsole 1 1ServerIronADX1/1 #show ipv6 map-statistics ************************ V6-V4 Gateway STATISTICS *************************

Memory Allocation Statistics: ----------------------------- Tables memory(bytes) = 16799984 Static map memory (bytes) = 448 IPv6-6-4: 664 fwd = 25 664 rev = 55



IPv4 to IPv6 gatewayThe ServerIron ADX allows an IPv4 client to send and receive packets to and from any of the following real servers:



• a combination of IPv4 and IPv6 real servers

No special processing by the ServerIronADX is required for an IPv4 client to access an IPv4 real server.

Accessing an IPv6 real server from an IPv4 client, however, requires ServerIronADX to convert an IPv4 client address to an IPv6 client address using a user-defined unicast prefix. The ServerIronADX prepends this prefix to IPv4 source IP addresses in translated packets for IPv4 to IPv6 traffic and strips it away for IPv6 to IPv4 traffic.

Figure 55 shows how the ServerIron ADX constructs an IPv6 address using a user-defined IPv4-to-IPv6 prefix and the client IPv4 address.

FIGURE 55 IPv6 address using user-defined IPv4-to-IPv6 prefix and client IPv4 address

The ServerIron ADX uses the upper 64 bits of a package for the IPv4 to IPv6 prefix, the middle 32 bits for CAM (Content Addressable Memory) programming (to ensure that the package is correctly addressed), and the lower 32 bits for the client IPv4 address.

Figure 56 shows how the IPv4 client sends its request to the ServerIron ADX with its own IPv4 address as the source IP address. ServerIron ADX prepends a user-defined IPv6 prefix to the IPv4 client address to convert the IPv4 client address into an IPv6 address. The packets are then forwarded to the IPv6 server.

FIGURE 56 IPv4 client request converted to an IPv6 address



Figure 57 shows how the IPv6 server replies to the IPv4 client. In this example, the ServerIron ADX strips the IPv6 prefix from the IPv4 address.

FIGURE 57 IPv6 server reply converted to an IPv4 address

NOTESource NAT is not supported for the IPv4 or IPv6 gateway. Source NAT configured globally or on a real server do not take effect for a IPv4 VIP. If Source NAT is enabled for an IPv6 real server bound to an IPv4 VIP, a notification message will appear informing the user that source NAT will not take effect for the real server for the IPv4 VIP.

Configuring the IPv6 prefixAn IPv6 unicast prefix must be configured on the ServerIron ADX to convert IPv4 client addresses to IPv6 client addresses. This prefix is prepended to IPv4 source addresses in translated packets for IPv4 to IPv6 traffic and stripped away for IPv6 to IPv4 traffic. Furthermore, the prefix must be routed towards the ServerIron ADX on the IPv6 network.

NOTEThe IPv6 prefix must be in a dangling subnet.

The server ipv6 prefix is used to configure the IPv6 prefix that the ServerIron APX uses to convert IPv4 client addresses into IPv6 client addresses when sending packets from an IPv4 client to an IPv6 real server.

ServerIronADX(config)#server ipv6 prefix 2001:db8::/64 slb-446

Syntax: [no] server ipv6 prefix prefix length feature-list [inject-static-route]

The prefix variable defines the IPv6 gateway prefix; it must be configured in a dangling subnet.

The length variable defines the maximum length of the prefix. ServerIron ADX supports a prefix length of up to 64 bits.

The feature-list variable identifies a prefix that can be used to translate IPv4 addresses to IPv6 addresses by various ServerIron APX features. In the current implementation, only the “slb-446” parameter is supported.



The [inject-static-route] parameter can be used to inject a route using a protocol. This option can be used on the router platform.

The ipv6 prefix command is used to add a prefix to a vip-group. The prefix can be added to one vip-group at a time and is only applicable to the router platform.

ServerIronADX(config)#server vip-group 1ServerIronADX(config-vip-group-[1])#ipv6 prefix 2001:DB8::1/64

Syntax: [no] ipv6 prefix prefix/length

NOTEIn an SLB-446 setup, if another IPv6 VIP is defined such that the last 64 bits are the same as the IPv6 prefix, traffic will fail for that VIP. You need to configure the IPv6 prefix such that this is not the case.

Features not supported with the IPv4 to IPv6 gateway• NAT

• TRL

• VIP Protection

• Client-subnet-sticky

• Client-subnet base source-nat

• Real server hardware DSR

• Rule-based ACLv6 (only flow-based ACLs are supported)

• Source-nat ACLs

• Full-stack applications (SSL termination, etc.)

• FTP and other complex protocols

• One arm HA switch with Symmetric Active-Standby HA /Symmetric -Active-Active HA

• One arm standalone switch code

Packet fragmentation with the IPv4 to IPv6 gateway Packets sent from the IPv4 client to the IPv6 server can be too large and might need to be split into two IPv6 packets.

The ServerIron ADX uses the following criteria to assess whether packets are too large and need to be split:

Regular packets – IP total length greater than (IPv6 MTU -20) bytes

Fragmented packets – IP total length greater than (IPv6 MTU -20 +8) bytes for fragment header

If the packets exceed these limitations, the ServerIron ADX takes one of the following actions:

1. If the ipv6 frag-full-4to6 command is configured, the packet will be split and no further actions will be performed.

2. If the condition in step 1 isn’t met and the DF bit is set by the client, the “fragment needed” ICMP error message will be sent.



3. If the conditions in steps 1 and 2 aren’t met, the packet will be split.

The ipv6 frag-full-4to6 command is configured as shown in the following.

ServerIronADX(config)#ipv6 frag-full-4to6

Syntax: [no] ipv6 frag-full-4to6

ICMP packet processing for the IPv4 to IPv6 gateway Because the client is running IPv4 and the real server is running IPv6, ICMP and ICMPv6 error messages must be processed as described in the following:

• ICMP error messages from the IPv4 client side are translated to ICMPv6 messages and sent to the IPv6 server

• ICMPv6 error messages from the IPv6 server are translated to ICMP messages and sent to the IPv4 client

• ICMP and ICMPv6 echo request messages are processed by the management module (MP)

Client side ICMP packet translation

ICMP error messages are translated to equivalent ICMPv6 error messages as shown in Table 44

TABLE 44 ICMP to ICMPv6 error message translation



* net unreachable (code 0) * no route (code 0)

* host unreachable (code 1) * no route (code 0)

* protocol unreachable (code 2) * type - param prob, code - next header

* port unreachable (code 3) * no port (code 4)

* fragment needed (code 4) * type - packet too big, code - no route

* route fail (code 0) * not neighbor code (code 1)

* unknown dest network (code 1) * no route code (code 0)

* unknown dest host (code 2) * no route code (code 0)

* source host isolated (code 3) * no route code (code 0)

* dest network admin prohibited (code 4) * address prohibited (code 1)

* dest host admin prohibited (code 0) * address prohibited (code 1)

* network unreachable for tos (code 1) * no route code (code 0)

* host unreachable for tos (code 2) * no route code (code 0)

* admin prohibit (code 3) * admin prohibited (code 1)

* host precedence violated (code 4) * admin prohibited (code 1)

* precedence cutoff in effect (code ) * admin prohibited (code 1)

Destination Unreachable (Type 3)* fragment needed (code 4)

Packet Too Big (Type 2)



Server side ICMP packet translation


IPv4 to IPv6 gateway high availability supportHot standby, Symmetric Active-Standy, and Symmetric Active-Active high availability (HA) configurations are supported for the IPv4 to IPv6 gateway with the following considerations:

• The format for all high availability messages that do not contain IP address remain the same for IPv4 and IPv6 (for example, hot-standby heart beat).

• In a one-armed typology, the Symmetric Active-Standby HA and Symmetric Active-Active HA configuration are not supported for the IPv4 to IPv6 gateway. The Hot Standby HA configuration is supported.

Time Exceeded (Type 3) Time Exceeded (Type 11)* code remains the same from ICMPv6

Parameter Problem (Type 4)* next header


* Type - Dest Unreachable, code - protocol unreachable

* Type - param prob, code - 0

Echo Request (Type 8) Echo Request (Type 128)



ICMPv6 error message type ICMP error message type


* no route code (code 0) * host unreachable (code 1)

* admin prohibited (code 1) * admin prohibited (code 10)

* not neighbor (code 2) * route fail (code 5)

* address unreachable (code 3) * host unreachable (code 1)

* port unreachable (code 4) * port unreachable (code 3)

Packet Too Big (Type 2) Destination Unreachable (Type 3)* frament needed (code 4)

Time Exceeded (Type 3) Time Exceeded (Type 11)* code remains the same from ICMPv6

Parameter Problem (Type 4)* next header


* Type - Dest Unreachable, code - protocol unreachable

* Type - param prob, code - 0



TABLE 44 ICMP to ICMPv6 error message translation (Continued)




Session synchronization messages (which contain IP addresses) have added intelligence to handle IPv4 to IPv6 sessions that have IPv4 addresses for the forward sessions and IPv6 addresses (including destination IP constructed using the SLB 446 prefix) for reverse sessions.

Configuring the IPv4 to IPv6 gatewayTo configure the IPv4 to IPv6 gateway, you must define a unicast IPv6 prefix. ADX uses this prefix to convert IPv4 client addresses to IPv6 client addresses when sending packages from an IPv4 client to an IPv6 real server. You must perform the following configurations:

• Configure the IPv6 prefix for converting an IPv4 client IP to an IPv6 client IP

• Configure an IPv6 real server

• Configure an IPv4 VIP

• Bind port http of IPv4 VIP to port http of IPv6 real server


The following example provides a sample configuration for the ServerIron ADX in Figure 56 and Figure 57.

The following command configures the unicast IPv6 prefix:

ServerIronADX (config) #server ipv6 prefix 2001:db8:1::/64 slb-446

The following commands configure an IPv6 real server:

ServerIronADX (config)#server real rs1 2001:db8:2::1ServerIronADX (config-rs-rs1)#port httpServerIronADX (config-rs-rs1) port http url "HEAD /"

ServerIronADX (config)#server real rs2 2001:db8:2::2ServerIronADX (config-rs-rs2)#port httpServerIronADX (config-rs-rs2)#port http url "HEAD /"

The following command configures an IPv4 VIP:

server virtual v4-vip 10.100.100.1 port http

The following command binds the IPv4 VIP application port to the IPv6 real server application port.

bind http rsl http rs2 http

Displaying IPv4 to IPv6 gateway informationYou can use the show session all and show ipv6 map-statistics commands to display information about an IPv4 to IPv6 gateway. These commands work just as described in “Displaying IPv6 to IPv4 gateway information” on page 450.

The show ipv6 client-4to6 command displays the IPv6 client address generated for an IPv4 client address using the IPv4 to IPv6 gateway.

ServerIronADX#rconsole 1 1ServerIronADX1/1#show ipv6 client-4to6 10.100.100.1



Appendix

A
Server-specific Loopback Configurations
OverviewYou can configure loopback addresses on some common types of real servers.

NOTEThe information in this appendix is based on information from the vendors of these servers. For more information, please consult your real server vendor.

SolarisTo configure a loopback address on Solaris, enter the following command.

ifconfig lo0:1 vip-addr netmask net-mask up

You might need to “plumb” the interface first. In this case, enter the following commands.

ifconfig lo0:1 plumbifconfig lo0:1 vip-addr netmask net-mask up

NOTEThe pervious specified commands apply to the current running configuration only. To make the address permanent so that it is reconfigured following a reboot or power cycle, create the file /etc/hostname.lo0:1.

NOTEFor Hewlett-Packard (HP) version 11.x, use the May 2000 or later patch.

LinuxTo configure a loopback interface on Linux, enter a command such as the following.

ifconfig lo:0 vip-addr netmask net-mask up

NOTEThe ifconfig lo:0 vip-addr netmask net-mask up command applies to the current running configuration only. To make the address permanent so that it is reconfigured following a reboot or power cycle, go to /etc/sysconfig/network-scripts and make a file called ifcfg-lo:0 using ifcfg-lo as a template.

457

Windows NTA

Windows NTTo configure a loopback interface on Windows NT, you need to configure a new network adapter. Use the following procedure. This procedure applies to the following products:

• Microsoft Windows 2000 Professional

• Microsoft Windows 2000 Server

• Microsoft Windows 2000 Advanced Server

• Microsoft Windows 2000 Datacenter Server

NOTEWhen you add a loopback interface to Windows NT, it sometimes creates a route that has the same address as the loopback interface. You need to delete this route. In come cases, the procedure for deleting the route can include deleting the correct route to the server’s default gateway. When this is the case, you need to add this route back to Windows NT.

Manual installation1. Click Start, point to Settings, click Control Panel, and then double-click Add/Remove Hardware.

2. Click Add/Troubleshoot a device, and then click Next.

3. Click Add a new device, and then click Next.

4. Click No, I want to select the hardware from a list, and then click Next.

5. Click Network adapters, and then click Next.

6. In the Manufacturers box, click Microsoft.

7. In the Network Adapter box, click Microsoft Loopback Adapter, and then click Next.

8. Click Finish.

After the adapter is installed successfully, you can configure its options manually, as with any other adapter.

NOTEIf the TCP/IP properties are configured to use DHCP (the default), the adapter will eventually use an autonet address (169.254.x.x/16) because it is not actually connected to any physical media.

Unattended installationModify the Unattend.txt file using the following example as a guide to install the Microsoft Loopback adapter.

[NetAdapters]Adapter01=Params.Adapter01[Params.Adapter01]InfID="*msloop" ; Microsoft Loopback AdapterConnectionName = "MS Loopback Adapter"[NetProtocols]MS_TCPIP=Params.MS_TCPIP; TCP/IP parameters; Use parameter values specific to your network


Windows NT A

[Params.MS_TCPIP]AdapterSections=params.TCPIP.Adapter01DNS=yesDNSSuffixSearchOrder=mycorp.comEnableLMHosts=No; Adapter Specific TCP/IP parameters; Use parameter values specific to your network[params.TCPIP.Adapter01]SpecificTo=Adapter01DNSDomain=mycorp.comDNSServerSearchOrder=192.168.5.251WINS=noDHCP=noIPAddress=192.168.5.10SubnetMask=255.255.255.0DefaultGateway=192.168.5.254

Deleting the unwanted routesIn some cases,Windows NT creates a route that has the same address as the loopback interface. You need to delete this route.

Two methods are shown in this section. If you receive an error message while trying to use the simple method, you need to use the long method instead.

NOTERegardless of the method you use, you must repeat the procedure every time the Windows NT server is booted. However, you can create a small batch file to enter these commands and add the batch file to the AT subsystem so that the file runs automatically each time the server is booted.

Simple method

The simple method requires you to delete the route that Windows NT creates when you add the loopback interface. The route you need to delete is the one that has the same IP address as the loopback interface.

1. Enter the route print command to display the server’s route table. In this example, the loopback interface has address 192.168.200.106.

.

C:\>route print

Active Routes:

Network Address Netmask Gateway Address Interface Metric 0.0.0.0 0.0.0.0 192.168.204.254 192.168.200.251 1 10.0.0.0 255.0.0.0 10.0.0.1 10.0.0.1 1 192.168.200.0 255.255.255.0 192.168.200.106 192.168.200.106 1 192.168.200.0 255.255.255.0 192.168.200.251 192.168.200.251 1 192.168.200.106 255.255.255.255 10.0.0.1 10.0.0.1 1 192.168.200.251 255.255.255.255 10.0.0.1 10.0.0.1 1 192.168.200.255 255.255.255.255 192.168.200.251 192.168.200.251 1 224.0.0.0 224.0.0.0 192.168.200.106 192.168.200.106 1 224.0.0.0 224.0.0.0 192.168.200.251 192.168.200.251 1 10.255.255.255 255.255.255.255 192.168.200.251 192.168.200.251 1


Windows NTA

2. Delete the route that has the same address as the loopback interface.

C:\>route delete 192.168.200.0 mask 255.255.255.0 192.168.200.106

3. Display the route table again to verify that the unwanted route is gone.

Long method

The long method, like the short method, requires you to delete the route that Windows NT creates when you add the loopback interface. However, what makes this method is long is that in some cases, when the route table has more than one route in the network that contains the loopback interface, the route delete command deletes the wrong route. In this case, you need to enter the command again to delete the route that has the loopback address, then re-add the other route.

1. Enter the route print command to display the server’s route table. In this example, the loopback interface has address 192.168.200.106. Notice that the route table also contains another route (192.168.200.250) in the same network. The 192.168.200.250 route is the gateway route and needs to stay in the route table.

.

2. Enter the route delete command to delete the unwanted 192.168.200.106 route.

C:\users\default>route delete 192.168.200.0 mask 255.255.255.0 192.168.200.106

C:\>route print

Active Routes:

Network Address Netmask Gateway Address Interface Metric 0.0.0.0 0.0.0.0 192.168.204.254 192.168.200.251 1 10.0.0.0 255.0.0.0 10.0.0.1 10.0.0.1 1 192.168.200.0 255.255.255.0 192.168.200.251 192.168.200.251 1 192.168.200.106 255.255.255.255 10.0.0.1 10.0.0.1 1 192.168.200.251 255.255.255.255 10.0.0.1 10.0.0.1 1 192.168.200.255 255.255.255.255 192.168.200.251 192.168.200.251 1 224.0.0.0 224.0.0.0 192.168.200.106 192.168.200.106 1 224.0.0.0 224.0.0.0 192.168.200.251 192.168.200.251 1 10.255.255.255 255.255.255.255 192.168.200.251 192.168.200.251 1

C:\users\default>route print

Active Routes:

Network Address Netmask Gateway Address Interface Metric 0.0.0.0 0.0.0.0 192.168.200.254 192.168.200.250 1 10.0.0.0 255.0.0.0 10.0.0.1 10.0.0.1 1 192.168.200.0 255.255.255.0 192.168.200.250 192.168.200.250 1 192.168.200.0 255.255.255.0 192.168.200.106 192.168.200.106 1 192.168.200.106 255.255.255.255 10.0.0.1 10.0.0.1 1 192.168.200.250 255.255.255.255 10.0.0.1 10.0.0.1 1 192.168.200.255 255.255.255.255 192.168.200.106 192.168.200.106 1 224.0.0.0 224.0.0.0 192.168.200.250 192.168.200.250 1 224.0.0.0 224.0.0.0 192.168.200.106 192.168.200.106 1 10.255.255.255 255.255.255.255 192.168.200.106 192.168.200.106 1


Windows NT A

3. Display the route table again to verify the results. In this example, Windows NT deletes the first 192.168.200.x route in the table instead of deleting the route you want to delete. If this occurs when you are performing this procedure, go to step 4. Otherwise, you are finished with this procedure.

4. Enter the route delete command again to delete the unwanted route.

C:\users\default>route delete 192.168.200.0 mask 255.255.255.0

192.168.200.106

5. Display the route table again to verify the results. In this example, none of the 192.168.200.x routes remain in the table.


Active Routes:



Active Routes:

Network Address Netmask Gateway Address Interface Metric 0.0.0.0 0.0.0.0 192.168.200.254 192.168.200.250 1 10.0.0.0 255.0.0.0 10.0.0.1 10.0.0.1 1 192.168.200.106 255.255.255.255 10.0.0.1 10.0.0.1 1 192.168.200.250 255.255.255.255 10.0.0.1 10.0.0.1 1 192.168.200.255 255.255.255.255 192.168.200.106 192.168.200.106 1 224.0.0.0 224.0.0.0 192.168.200.250 192.168.200.250 1 224.0.0.0 224.0.0.0 192.168.200.106 192.168.200.106 1 10.255.255.255 255.255.255.255 192.168.200.106 192.168.200.106 1


Windows NTA

6. Enter the route add command to re-add the gateway route.

C:\users\default>route add 192.168.200.0 mask 255.255.255.0 192.168.200.250

7. Display the route table again to verify that the table contains the gateway route but does not contain a route with the loopback address.


Active Routes:




Appendix

B
Basic Configuration Example
OverviewConsider the example where VIP 10.1.1.10 is configured on three ServerIrons ADXs(A, B and C). The following is the step-by-step VIP RHI configuration for ServerIron ADX A.

1. Ensure a routing protocol is running, such as OSPF.

ServerIronADXA(config)#vlan 9ServerIronADXA(config-vlan-9)#untagged ethernet 4/1 to 4/5ServerIronADXA(config-vlan-9)#router-interface ve 9ServerIronADXA(config-vlan-9)#exit ServerIronADXA(config)#router ospfServerIronADXA(config-ospf-router)#area 0ServerIronADXA(config-ospf-router)#redistribution staticServerIronADXA(config-ospf-router)#exit ServerIronADXA(config)#interface ve 9ServerIronADXA(config-ve-9)#ip address 10.211.21.11 255.255.255.0ServerIronADXA(config-ve-9)#ip ospf area 0ServerIronADXA(config-ve-9)#exit

2. Configure the interface associated with the VIP.

ServerIronADXA(config)#interface ethernet 4/15ServerIronADXA(config-if-4/15)#ip address 10.1.1.99 255.255.255.0ServerIronADXA(config-if-4/15)#ip dont-advertise 10.1.1.99 255.255.255.0 ServerIronADXA(config-if-4/15)#exit

3. Enable the real servers and ports.

ServerIronADXA#con tServerIronADXA(config)#server real rs1 10.1.1.20ServerIronADXA(config-rs-rs1)#port httpServerIronADXA(config-rs-rs1)#exitServerIronADXA(config)#server real rs2 10.1.1.30ServerIronADXA(config-rs-rs2)#port httpServerIronADXA(config-rs-rs2)#exit

4. Set the VIP, bind VIP ports to real server ports, and enable VIP RHI.

ServerIronADXA(config)#server virtual-name-or-ip vip-si-A 10.1.1.10ServerIronADXA(config-vs-vip-si-A)#port httpServerIronADXA(config-vs-vip-si-A)#bind http rs1 http rs2 httpServerIronADXA(config-vs-vip-si-A)#advertise-vip-routeServerIronADXA(config-vs-vip-si-A)#exit

The configuration is similar for ServerIron ADX B and C (with relevant interface IP addresses).

463

Both ServerIron ADX sites working in primary modeB

Both ServerIron ADX sites working in primary modeFIGURE 58 Primary mode


Both ServerIron ADX sites working in primary mode B

Site 1 configurationver 09.3.00b265TD4!module 1 bi-0-port-wsm2-management-modulemodule 2 bi-jc-8-port-gig-modulemodule 3 bi-jc-16-port-gig-copper-modulemodule 4 bi-jc-16-port-gig-copper-module!global-protocol-vlan!!server predictor round-robinserver global-advertise-vip-routeserver global-vip-route-mask-length 30server rhi-active-bindings-threshold 80

server port 21 tcpserver port 80 tcpserver port 53 udpserver port 161 udpserver port 25 tcpserver port 443 tcpserver port 8601 tcp!!server real rs1 10.20.1.40 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real rs2 10.20.1.41 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server remote-name test 10.30.1.40 source-nat port http port http url "HEAD /"



port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real Web1 10.60.1.40 port 8601!server real Web2 10.60.1.41 port 8601!server real Web3 10.60.1.42 port 8601!server real Web4 10.60.1.43 port 8601!server real Web5 10.60.1.44 port 8601!server real Web6 10.60.1.45 port 8601!server real Web7 10.60.1.46 port 8601!server real Web8 10.60.1.47 port 8601!server real Web9 10.60.1.48 port 8601!server real Web10 10.60.1.49 port 8601!server real wr1 10.50.1.40 port http port http url "HEAD /"!server real wr2 10.50.1.41 port http port http url "HEAD /"!server real wr3 10.50.1.42 port http port http url "HEAD /"!server real wr4 10.50.1.43 port http port http url "HEAD /"!server real wr5 10.50.1.44 port http port http url "HEAD /"!server real wr6 10.50.1.45 port http



port http url "HEAD /"!server real wr7 10.50.1.46 port http port http url "HEAD /"!server real wr8 10.50.1.47 port http port http url "HEAD /"!server real wr9 10.50.1.48 port http port http url "HEAD /"!server real wr10 10.50.1.49 port http port http url "HEAD /"!server remote-name rem1 10.80.1.40 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!server remote-name rem2 10.80.1.41 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!!server virtual-name-or-ip vip60 10.60.1.10 port http bind http Web1 8601 Web2 8601 Web3 8601 Web4 8601 bind http Web5 8601 Web6 8601 Web7 8601 Web8 8601 bind http Web9 8601 Web10 8601!server virtual-name-or-ip vip50 10.50.1.10 port http bind http wr1 http wr2 http wr3 http wr4 http bind http wr5 http wr6 http wr7 http wr8 http bind http wr9 http wr10 http!server virtual-name-or-ip vip70 10.70.1.10 port http port smtp port ftp port dns port snmp port mms



port rtsp bind http test http bind smtp test smtp bind ftp test ftp bind dns test dns bind snmp test snmp bind mms test mms bind rtsp test rtsp!server virtual-name-or-ip vip90 10.90.1.10 vip-route-subnet-mask-length 28 port dns port snmp port http port ftp bind dns rem1 dns rem2 dns bind snmp rem1 snmp rem2 snmp bind http rem1 8601 rem2 8601 bind ftp rem1 ftp rem2 ftp!server virtual-name-or-ip vip20 10.20.1.10 disable-advertise-vip-route port http port dns port snmp port ftp bind http rs1 http rs2 http bind dns rs1 dns rs2 dns bind snmp rs1 snmp rs2 snmp bind ftp rs1 ftp rs2 ftp!!vlan 1 name DEFAULT-VLAN by port!vlan 10 by port untagged ethe 2/1 to 2/4 router-interface ve 1!vlan 20 by port untagged ethe 4/1 to 4/16 router-interface ve 2!vlan 30 by port tagged ethe 2/5 untagged ethe 2/8 router-interface ve 3!vlan 40 by port tagged ethe 2/5 untagged ethe 2/6 to 2/7 router-interface ve 4!!hostname Site1-SIlogging buffered 1000mirror ethernet 4/12!server session-debug 100000auto-cam-repaintpram-write-retry



!router ospf area 0 metric-type type1 redistribution connected redistribution static !interface loopback 1 ip address 10.100.100.100 255.255.255.255 ip ospf area 0!interface ethernet 2/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/5 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 3/12 ip address 10.70.1.120 255.255.255.0 ip dont-advertise 10.70.1.120 255.255.255.0 ip address 10.90.1.120 255.255.255.0 ip dont-advertise 10.90.1.120 255.255.255.0 !interface ethernet 4/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/16 mon ethe 4/12 input mon ethe 4/12 output!interface ve 1 ip address 10.40.1.120 255.255.255.0 ip address 10.40.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 2 ip address 10.20.1.120 255.255.255.0 ip address 10.20.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 3 ip address 10.60.1.120 255.255.255.0 ip dont-advertise 10.60.1.120 255.255.255.0 ip address 10.60.1.121 255.255.255.0 secondary ip dont-advertise 10.60.1.121 255.255.255.0 !



interface ve 4 ip address 10.50.1.120 255.255.255.0 ip dont-advertise 10.50.1.120 255.255.255.0 ip address 10.50.1.121 255.255.255.0 secondary ip dont-advertise 10.50.1.121 255.255.255.0 !!end

Site 2 configurationver 09.3.00b265TD4

module 1 bi-0-port-wsm2-management-modulemodule 2 bi-jc-8-port-gig-modulemodule 3 bi-jc-16-port-gig-copper-modulemodule 4 bi-jc-16-port-gig-copper-module!global-protocol-vlan!!server predictor round-robinserver global-advertise-vip-route server global-vip-route-mask-length 30 server rhi-active-bindings-threshold 80

server port 21 tcp

server port 80 tcp

server port 53 udp

server port 161 udp

server port 25 tcp

server port 443 tcp

server port 8601 tcp!!!server real rs1 10.120.1.40 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp



!server real rs2 10.120.1.41 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server remote-name test 10.130.1.40 source-nat port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real Web1 10.60.1.40 port 8601!server real Web2 10.60.1.41 port 8601!server real Web3 10.60.1.42 port 8601!server real Web4 10.60.1.43 port 8601!server real Web5 10.60.1.44 port 8601!server real Web6 10.60.1.45 port 8601!server real Web7 10.60.1.46 port 8601!server real Web8 10.60.1.47 port 8601!server real Web9 10.60.1.48 port 8601!server real Web10 10.60.1.49 port 8601!server real wr1 10.50.1.40 port http port http url "HEAD /"!server real wr2 10.50.1.41 port http



port http url "HEAD /"!server real wr3 10.50.1.42 port http port http url "HEAD /"!server real wr4 10.50.1.43 port http port http url "HEAD /"!server real wr5 10.50.1.44 port http port http url "HEAD /"!server real wr6 10.50.1.45 port http port http url "HEAD /"!server real wr7 10.50.1.46 port http port http url "HEAD /"!server real wr8 10.50.1.47 port http port http url "HEAD /"!server real wr9 10.50.1.48 port http port http url "HEAD /"!server real wr10 10.50.1.49 port http port http url "HEAD /"!server remote-name rem1 10.180.1.40 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!server remote-name rem2 10.180.1.41 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!!



server virtual-name-or-ip vip60 10.60.1.10 port http bind http Web1 8601 Web2 8601 Web3 8601 Web4 8601 bind http Web5 8601 Web6 8601 Web7 8601 Web8 8601 bind http Web9 8601 Web10 8601!server virtual-name-or-ip vip50 10.50.1.10 port http bind http wr1 http wr2 http wr3 http wr4 http bind http wr5 http wr6 http wr7 http wr8 http bind http wr9 http wr10 http!server virtual-name-or-ip vip70 10.70.1.10 port http port smtp port ftp port dns port snmp port mms port rtsp bind http test http bind smtp test smtp bind ftp test ftp bind dns test dns bind snmp test snmp bind mms test mms bind rtsp test rtsp!server virtual-name-or-ip vip90 10.90.1.10 vip-route-subnet-mask-length 28 port dns port snmp port http port ftp bind dns rem1 dns rem2 dns bind snmp rem1 snmp rem2 snmp bind http rem1 8601 rem2 8601 bind ftp rem1 ftp rem2 ftp!server virtual-name-or-ip vip120 10.120.1.10 disable-advertise-vip-route port http port dns port snmp port ftp bind http rs1 http rs2 http bind dns rs1 dns rs2 dns bind snmp rs1 snmp rs2 snmp bind ftp rs1 ftp rs2 ftp!!vlan 1 name DEFAULT-VLAN by port!vlan 10 by port untagged ethe 2/1 to 2/4 router-interface ve 1!



vlan 20 by port untagged ethe 4/1 to 4/16 router-interface ve 2!vlan 30 by port tagged ethe 2/5 untagged ethe 2/8 router-interface ve 3!vlan 40 by port tagged ethe 2/5 untagged ethe 2/6 to 2/7 router-interface ve 4!!hostname Site2-SIlogging buffered 1000mirror ethernet 4/12!server session-debug 100000auto-cam-repaintpram-write-retry!router ospf area 0 metric-type type1 redistribution connected redistribution static !interface loopback 1 ip address 10.100.100.101 255.255.255.255 ip ospf area 0!interface ethernet 2/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/5 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 3/12 ip address 10.70.1.120 255.255.255.0 ip dont-advertise 10.70.1.120 255.255.255.0 ip address 10.90.1.120 255.255.255.0 ip dont-advertise 10.90.1.120 255.255.255.0 !interface ethernet 4/1 mon ethe 4/12 input mon ethe 4/12 output!



interface ethernet 4/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/16 mon ethe 4/12 input mon ethe 4/12 output!interface ve 1 ip address 10.140.1.120 255.255.255.0 ip address 10.140.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 2 ip address 10.120.1.120 255.255.255.0 ip address 10.120.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 3 ip address 10.60.1.120 255.255.255.0 ip dont-advertise 10.60.1.120 255.255.255.0 ip address 10.60.1.121 255.255.255.0 secondary ip dont-advertise 10.60.1.121 255.255.255.0 !interface ve 4 ip address 10.50.1.120 255.255.255.0 ip dont-advertise 10.50.1.120 255.255.255.0 ip address 10.50.1.121 255.255.255.0 secondary ip dont-advertise 10.50.1.121 255.255.255.0 !end


Site-1 ServerIron ADX in primary mode and site-2 in backup modeB

Site-1 ServerIron ADX in primary mode and site-2 in backup modeFIGURE 59 Primary mode and backup mode


Site-1 ServerIron ADX in primary mode and site-2 in backup mode B

Site 1 configurationThe following configuration is only for virtual server vip60 (10.60.1.10).

!ver 09.3.00b269TD4!module 1 bi-0-port-wsm2-management-modulemodule 2 bi-jc-8-port-gig-modulemodule 3 bi-jc-16-port-gig-copper-modulemodule 4 bi-jc-16-port-gig-copper-module!global-protocol-vlan!!server predictor round-robinserver global-advertise-vip-routeserver global-vip-route-mask-length 30server rhi-active-bindings-threshold 80

server port 21 tcp

server port 80 tcp

server port 53 udp

server port 161 udp

server port 25 tcp

server port 443 tcp

server port 8601 tcp!!server real rs1 10.20.1.40 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real rs2 10.20.1.41 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com"



port snmp port mms port rtsp!server remote-name test 10.30.1.40 source-nat port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real Web1 10.60.1.40 port 8601!server real Web2 10.60.1.41 port 8601!server real Web3 10.60.1.42 port 8601!server real Web4 10.60.1.43 port 8601!server real Web5 10.60.1.44 port 8601!server real Web6 10.60.1.45 port 8601!server real Web7 10.60.1.46 port 8601!server real Web8 10.60.1.47 port 8601!server real Web9 10.60.1.48 port 8601!server real Web10 10.60.1.49 port 8601!server real wr1 10.50.1.40 port http port http url "HEAD /"!server real wr2 10.50.1.41 port http port http url "HEAD /"!server real wr3 10.50.1.42 port http port http url "HEAD /"!server real wr4 10.50.1.43 port http



port http url "HEAD /"!server real wr5 10.50.1.44 port http port http url "HEAD /"!server real wr6 10.50.1.45 port http port http url "HEAD /"!server real wr7 10.50.1.46 port http port http url "HEAD /"!server real wr8 10.50.1.47 port http port http url "HEAD /"!server real wr9 10.50.1.48 port http port http url "HEAD /"!server real wr10 10.50.1.49 port http port http url "HEAD /"!server remote-name rem1 10.80.1.40 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!server remote-name rem2 10.80.1.41 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!!server virtual-name-or-ip vip60 10.60.1.10 port http bind http Web1 8601 Web2 8601 Web3 8601 Web4 8601 bind http Web5 8601 Web6 8601 Web7 8601 Web8 8601 bind http Web9 8601 Web10 8601!server virtual-name-or-ip vip50 10.50.1.10 port http bind http wr1 http wr2 http wr3 http wr4 http bind http wr5 http wr6 http wr7 http wr8 http bind http wr9 http wr10 http



!server virtual-name-or-ip vip70 10.70.1.10 port http port smtp port ftp port dns port snmp port mms port rtsp bind http test http bind smtp test smtp bind ftp test ftp bind dns test dns bind snmp test snmp bind mms test mms bind rtsp test rtsp!server virtual-name-or-ip vip90 10.90.1.10 vip-route-subnet-mask-length 28 port dns port snmp port http port ftp bind dns rem1 dns rem2 dns bind snmp rem1 snmp rem2 snmp bind http rem1 8601 rem2 8601 bind ftp rem1 ftp rem2 ftp!server virtual-name-or-ip vip20 10.20.1.10 disable-advertise-vip-route port http port dns port snmp port ftp bind http rs1 http rs2 http bind dns rs1 dns rs2 dns bind snmp rs1 snmp rs2 snmp bind ftp rs1 ftp rs2 ftp!vlan 1 name DEFAULT-VLAN by port!vlan 10 by port untagged ethe 2/1 to 2/4 router-interface ve 1!vlan 20 by port untagged ethe 4/1 to 4/16 router-interface ve 2!vlan 30 by port tagged ethe 2/5 untagged ethe 2/8 router-interface ve 3!vlan 40 by port tagged ethe 2/5 untagged ethe 2/6 to 2/7 router-interface ve 4!!



hostname Site1-SIlogging buffered 1000mirror ethernet 4/12!server session-debug 100000auto-cam-repaintpram-write-retry!router ospf area 0 metric-type type1 redistribution connected redistribution static !interface loopback 1 ip address 10.100.100.100 255.255.255.255 ip ospf area 0!interface ethernet 2/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/5 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 3/12 ip address 10.70.1.120 255.255.255.0 ip dont-advertise 10.70.1.120 255.255.255.0 ip address 10.90.1.120 255.255.255.0 ip dont-advertise 10.90.1.120 255.255.255.0!interface ethernet 4/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/16 mon ethe 4/12 input mon ethe 4/12 output!interface ve 1 ip address 10.40.1.120 255.255.255.0 ip address 10.40.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 2 ip address 10.20.1.120 255.255.255.0 ip address 10.20.1.121 255.255.255.0 secondary ip ospf area 0!



interface ve 3 ip address 10.60.1.120 255.255.255.0 ip dont-advertise 10.60.1.120 255.255.255.0 ip address 10.60.1.121 255.255.255.0 secondary ip dont-advertise 10.60.1.121 255.255.255.0!interface ve 4 ip address 10.50.1.120 255.255.255.0 ip dont-advertise 10.50.1.120 255.255.255.0 ip address 10.50.1.121 255.255.255.0 secondary ip dont-advertise 10.50.1.121 255.255.255.0!end

Site 2 configuration!ver 09.3.00b269TD4!module 1 bi-0-port-wsm2-management-modulemodule 2 bi-jc-8-port-gig-modulemodule 3 bi-jc-16-port-gig-copper-modulemodule 4 bi-jc-16-port-gig-copper-module!global-protocol-vlan!!healthck Site1-chk icmp dest-ip 10.40.1.120

healthck Site1-NOT boolean not Site1-chk












healthck Web10-8601-chk tcp dest-ip 10.60.1.49 port 8601 protocol http protocol http url "HEAD /"



interval 20 retries 4 l7-check










healthck Web10-chk boolean and Site1-NOT Web10-8601-chk!server predictor round-robinserver global-advertise-vip-routeserver global-vip-route-mask-length 30server rhi-active-bindings-threshold 80

server port 21 tcpserver port 80 tcpserver port 53 udpserver port 161 udpserver port 25 tcpserver port 443 tcpserver port 8601 tcp!!server real rs1 10.120.1.40 port http port http url "HEAD /" port ftp port smtp



port dns port dns zone "example9.com" port snmp port mms port rtsp!server real rs2 10.120.1.41 port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server remote-name test 10.130.1.40 source-nat port http port http url "HEAD /" port ftp port smtp port dns port dns zone "example9.com" port snmp port mms port rtsp!server real Web1 10.60.1.40 port 8601 port 8601 healthck Web1-chk!server real Web2 10.60.1.41 port 8601 port 8601 healthck Web2-chk!server real Web3 10.60.1.42 port 8601 port 8601 healthck Web3-chk!server real Web4 10.60.1.43 port 8601 port 8601 healthck Web4-chk!server real Web5 10.60.1.44 port 8601 port 8601 healthck Web5-chk!server real Web6 10.60.1.45 port 8601 port 8601 healthck Web6-chk!server real Web7 10.60.1.46 port 8601 port 8601 healthck Web7-chk!server real Web8 10.60.1.47 port 8601 port 8601 healthck Web8-chk



!server real Web9 10.60.1.48 port 8601 port 8601 healthck Web9-chk!server real Web10 10.60.1.49 port 8601 port 8601 healthck Web10-chk!server real wr1 10.50.1.40 port http port http url "HEAD /"!server real wr2 10.50.1.41 port http port http url "HEAD /"!server real wr3 10.50.1.42 port http port http url "HEAD /"!server real wr4 10.50.1.43 port http port http url "HEAD /"!server real wr5 10.50.1.44 port http port http url "HEAD /"!server real wr6 10.50.1.45 port http port http url "HEAD /"!server real wr7 10.50.1.46 port http port http url "HEAD /"!server real wr8 10.50.1.47 port http port http url "HEAD /"!server real wr9 10.50.1.48 port http port http url "HEAD /"!server real wr10 10.50.1.49 port http port http url "HEAD /"!server remote-name rem1 10.180.1.40 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!



server remote-name rem2 10.180.1.41 port 8601 port ftp port smtp port ssl port dns port dns zone "example9.com" port snmp port mms port rtsp!!server virtual-name-or-ip vip60 10.60.1.10 port http bind http Web1 8601 Web2 8601 Web3 8601 Web4 8601 bind http Web5 8601 Web6 8601 Web7 8601 Web8 8601 bind http Web9 8601 Web10 8601!server virtual-name-or-ip vip50 10.50.1.10 port http bind http wr1 http wr2 http wr3 http wr4 http bind http wr5 http wr6 http wr7 http wr8 http bind http wr9 http wr10 http!server virtual-name-or-ip vip70 10.70.1.10 port http port smtp port ftp port dns port snmp port mms port rtsp bind http test http bind smtp test smtp bind ftp test ftp bind dns test dns bind snmp test snmp bind mms test mms bind rtsp test rtsp!server virtual-name-or-ip vip90 10.90.1.10 vip-route-subnet-mask-length 28 port dns port snmp port http port ftp bind dns rem1 dns rem2 dns bind snmp rem1 snmp rem2 snmp bind http rem1 8601 rem2 8601 bind ftp rem1 ftp rem2 ftp!server virtual-name-or-ip vip120 10.120.1.10 disable-advertise-vip-route port http port dns port snmp port ftp bind http rs1 http rs2 http bind dns rs1 dns rs2 dns bind snmp rs1 snmp rs2 snmp



bind ftp rs1 ftp rs2 ftp!!vlan 1 name DEFAULT-VLAN by port!vlan 10 by port untagged ethe 2/1 to 2/4 router-interface ve 1!vlan 20 by port untagged ethe 4/1 to 4/16 router-interface ve 2!vlan 30 by port tagged ethe 2/5 untagged ethe 2/8 router-interface ve 3!vlan 40 by port tagged ethe 2/5 untagged ethe 2/6 to 2/7 router-interface ve 4!!hostname Site2-SIlogging buffered 1000mirror ethernet 4/12!server session-debug 100000auto-cam-repaintpram-write-retry!router ospf area 0 metric-type type1 redistribution connected redistribution static !interface loopback 1 ip address 10.100.100.101 255.255.255.255 ip ospf area 0!interface ethernet 2/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 2/5 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 3/12 ip address 10.70.1.120 255.255.255.0 ip dont-advertise 10.70.1.120 255.255.255.0 ip address 10.90.1.120 255.255.255.0 ip dont-advertise 10.90.1.120 255.255.255.0!



interface ethernet 4/1 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/2 mon ethe 4/12 input mon ethe 4/12 output!interface ethernet 4/16 mon ethe 4/12 input mon ethe 4/12 output!interface ve 1 ip address 10.140.1.120 255.255.255.0 ip address 10.140.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 2 ip address 10.120.1.120 255.255.255.0 ip address 10.120.1.121 255.255.255.0 secondary ip ospf area 0!interface ve 3 ip address 10.60.1.120 255.255.255.0 ip dont-advertise 10.60.1.120 255.255.255.0 ip address 10.60.1.121 255.255.255.0 secondary ip dont-advertise 10.60.1.121 255.255.255.0!interface ve 4 ip address 10.50.1.120 255.255.255.0 ip dont-advertise 10.50.1.120 255.255.255.0 ip address 10.50.1.121 255.255.255.0 secondary ip dont-advertise 10.50.1.121 255.255.255.0!end



Appendix

C
SLB Show and Debug Commands
Using show source-ipsource-ip [ real-server-ip | all] The show source-ip source-ip command displays the IP information, free ports, owner, start, and end for port pools for a specific source IP.

The show source-ip source-ip real-server-ip command displays the free ports, owner, start, and end for port pools for the specified source IP addresses and real server.

The show source-ip source-ip all command all displays the free ports, owner, start, and end for port pools for the specified source IP addresses for all real servers.

ServerIronADX#Show source-ip source-ip [real-server-ip | all]

Example

NOTEIf the show source-ip command displays that the IP is a per-real-srcip, then you should use the show source-ip source-ip real-server-ip command to view the port allocation and usage information, because the port allocation will be from the real server pool.

ServerIronADX#show source-ip 10.4.4.101 allSource IP information*********************Source IP: 10.4.4.101flt: Yes standby: No intf ip: No Real server: real-rs-8.10 (10.8.8.10)MMS: h: 0 t: 0 m: 23b4fb3c T: 642 f: 642RTSP: h: 0 t: 0 m: 23b51b54 T: 384 f: 384NORM: h: 0 t: 0 m: 23b34b24 T: 9216 f: 9216 Real server: real-rs-8.11 (10.8.8.11)MMS: h: 0 t: 0 m: 23b53b6c T: 642 f: 642RTSP: h: 0 t: 0 m: 23b55b84 T: 384 f: 384NORM: h: 0 t: 0 m: 280c1d08 T: 9216 f: 9216 Real server: real-rs-8.12 (10.8.8.12)MMS: h: 0 t: 0 m: 23b58114 T: 642 f: 642 RTSP: h: 0 t: 0 m: 23b5a12c T: 384 f: 384NORM: h: 0 t: 0 m: 280dcd20 T: 9216 f: 9216

491

Using the show session all commandC

Using the show session all commandUse the show session command (available at the BP console only) to determine if the sessions have been created correctly.

.

In the above example, 10.1.1.42 is the client and 10.1.1.99 is the VIP address. The IP address 10.1.15 is the real server and 10.1.1.79 is the source NAT IP.

NOTEIn the reverse session, the port 10242 has been allocated from the pool of real server 10.1.1.15.

You can verify the information by using the show source-ip command.

.

The output shows that of a total of 27648 ports, one port has been allocated and 27467 are still available.

ServerIronADX#rconsole 1 1ServerIronADX 1/1#show session all 0 Session Info:

Flags- 0:UDP, 1:TCP, >:fwdSess, +:userCntFlgSet, D:sessInDelQ, F:fin_setFlg, A:acked * before age indicates that the static bit is set

Index Src-IP Dst-IP S-port D-port Age Serv Flags===== ====== ====== ====== ====== === ==== ==========0 10.0.0.5 10.1.1.36 5 80 *0 n/a SLB1 #1 10.0.0.5 10.1.1.99 5 80 *0 n/a SLB1 #2 10.1.1.15 10.1.1.79 80 10242 32 n/a OPT1 #3 10.1.1.15 10.1.1.79 80 10242 - rest SLB1 A4 10.1.1.42 10.1.1.99 1333 80 33 n/a OPT1> #5 10.1.1.42 10.1.1.99 1333 80 - rest SLB1>+6 10.1.1.15 10.0.0.1 1 1 *60 n/a SLB1 #7 10.1.1.66 10.0.0.1 1 1 *60 n/a SLB1 #

ServerIronADX#show source-ip 10.1.1.79 10.1.1.15

Source IP information *********************Source IP: 10.1.1.79Real server: rest (10.1.1.15)

flt: Yes standby: No intf ip: Noport-range: 1 for ssl: No per-real-srcip: YesMMS: h: 0 t: 0 m: 23b4eb3c T: 1922 f: 1922RTSP: h: 0 t: 0 m: 23b50b54 T: 1024 f: 1024NORM: h: 3 t: 2 m: 23b33b24 T: 27648 f: 27647


Using the source-ip-debug command C

Using the source-ip-debug command

NOTEThis command should only be used for debugging purposes, because enabling it could impact performance.

You can configure the following command to enable debugging for source IP.

ServerIronADX(config)#source-ip-debug

Syntax: [no] source-ip-debug

Using the debug filter commandThe ServerIron ADX debug filter is a packet capture utility that captures packets at the ServerIron ADX itself based on user-defined filters. The captured packets are stored in a capture buffer and it is possible to view the packets on-screen or to transfer them to a TFTP server to have a look at them offline. The ServerIron ADX offers the possibility to store packet captures in PCAP format. This simplifies the work dramatically due to the fact that users are able to use PCAP based tools to work with the packet captures taken at the ServerIron ADX.

Using the packet capture utilityYou have to do the following to use the ServerIron ADX packet capture utility (debug filter):

1. enter utility

2. configure capture buffer

3. specify packet size to capture

4. specify filters

5. apply filters

6. start capturing process

7. stop capturing process

8. view captured packets

Enter Utility

To enter the debug filter, enter the following commands:

ServerIronADX> enaServerIronADX# debug filterServerIronADX(debug-filter)#


Using the debug filter commandC

Configuring Capture Buffer

You have to specify the size of the capture buffer in kilobytes. To set the buffer size, do the following:

ServerIronADX(debug-filter)# buffer-size 1024

Syntax: buffer-size kilobytes

To display the buffer size, do the following:

ServerIron(debug-filter)# buffer-size 1024

Syntax: buffer-size kilobytes

ServerIronADX(debug-filter)# show buffer-sizeCapture buffer size: 1048567 bytes

Specify packet size to capture

You can specify the number of bytes from a captured packet that are getting stored in the capture buffer. It is also possible to store the entire packet.

To set the amount of bytes to store, do the following:

ServerIronADX(debug-filter)# packet-size 128

Syntax: packet-size bytes | whole

The whole variable specifies that the entire packet needs to be stored in the capture buffer.

To show the currently configured packet size, enter the following command:

ServerIronADX(debug-filter)# show packet-sizeMax bytes stored from a filtered pkt: 128

Specify filter(s)

You specify the packets to store in the capture buffer by configuring one or more filter IDs. A filter ID consists of a set of filters that specify the attributes of packets to be stored in the capture buffer. You can configure up to 16 filter IDs.

Within a filter ID, you can specify filters for Layer 2 - 4 information in a packet. In addition, you can set up filters to capture packets that contain a specified pattern within the packet.

By default, a filter ID is configured to match any packet. Within a filter ID, all the filters must match a received packet in order for the packet to be captured. The filters not explicitly configured have "don't care" values, which are ignored during the matching process.

To specify the filter with ID 1:

ServerIronADX(debug-filter)#specify 1ServerIronADX(debug-filter-spec-1)#

Syntax: specify filter-id

You are able to specify filter settings at the filter ID configuration level. It is possible as well to display the current settings.


Using the debug filter command C

Table 46 displays the Ethernet Filter settings.

Table 47 displays the IP Filter settings.

Table 48 displays the TCP Filter settings.

Table 49 displays the UDP Filter settings.

TABLE 46 Ethernet Filter Settings

CLI Command Filter Type

mac bcast Ethernet broadcast packets

mac dest mac-address Packets with the specified destination MAC address

mac mcast Ethernet multicast packets

mac src mac-address Packets with the specified source MAC address

mac type type-in-hex Packets of the specified Layer 3 type

TABLE 47 IP Filter Settings


ip bcast IP broadcast packets

ip dest ip-address Packets with the specified destination IP address

ip mcast IP multicast packets

ip protocol protocol-in-hex Packets with the specified Layer 4 protocol

ip src ip-address Packets with the specified source IP address

TABLE 48 TCP Filter Settings


tcp src port-number Packets with the specified source TCP port

tcp dest port-number Packets with the specified destination TCP port

tcp syn TCP packets with the SYN flag on

tcp reset TCP packets with the RST flag on

tcp fin TCP packets with the FIN flag on

tcp ack TCP packets with the ACK flag on

tcp push TCP packets with the PSN flag on

tcp urgent TCP packets with the URG flag on

TABLE 49 UDP Filter Settings


udp src port-number Packets with the specified source UDP port

udp dest port-number Packets with the specified destination UDP port

tcp syn TCP packets with the SYN flag on

tcp reset TCP packets with the RST flag on

tcp fin TCP packets with the FIN flag on



Pattern matching filter settingsYou can set up a filter to capture packets that contain a pattern of a specified length, starting from a given offset from the beginning of the packet.

Example:

ServerIronADX(debug-filter-spec-1)#pattern 24 2 1023

Syntax: pattern offset length pattern-in-hex

The offset variable is the number of bytes from the start of the packet.The length variable is the length of the pattern in bytes. You can specify between 1 - 32 bytes.The pattern-in-hex variable is the pattern to match. The length of the pattern must be equal to the number of bytes specified with the length variable.

Example:

Create a filter to look for every packet from source IP 192.168.8.1 going to destination IP 192.168.8.222 - destination port 80:

ServerIronADX(debug-filter-spec-1)#ip src 192.168.8.1ServerIronADX(debug-filter-spec-1)#ip dest 192.168.8.222ServerIronADX(debug-filter-spec-1)#tcp dest 80

Use the show command to display the currently applied settings for the filter.

ServerIronADX(debug-filter-spec-1)#show

Filter-ID: 1MAC filters:

Src MAC : ANYDest MAC : ANYMAC Type : ANY

IP filters:Src IP : 192.168.8.1Dest IP : 192.168.8.222Protocol : ANY

TCP filters:Src port: ANYDest port: 80Flags : NoneUDP filters:Src port: ANYDest port: ANY

HTTP filters:Url : ANYCookie : ANY

Pattern filters:Pattern : ANY

Syntax: show

tcp ack TCP packets with the ACK flag on

tcp push TCP packets with the PSN flag on

tcp urgent TCP packets with the URG flag on

TABLE 49 UDP Filter Settings (Continued)




Use the reset command at the filter ID configuration level to restore the filter IDs default settings (match ALL).

ServerIronADX(debug-filter-spec-1)#reset

Syntax: reset

Use the exit command to leave the filter ID configuration level.

ServerIronADX(debug-filter-spec-1)#exitServerIronADX(debug-filter)#

Syntax: exit

It is also possible to display the setting for a filter ID at the debug filter level, as shown in the following example:

Syntax: show filter-id

Apply filter(s)

It is possible to define multiple filters like the one shown above - a filter is a set of matching criteria to select packets. A filter takes effect when you apply it. A filter ID should be applied globally or on an individual port. You can apply a filter ID so that it filters inbound traffic only, outbound traffic only, or both.

The following command applies filter 1 globally for inbound and outbound traffic:

ServerIronADX(debug-filter)# apply 1

Syntax: apply filter-id

You can apply multiple filter IDs and specify an and/or relationship between them. For example, to apply filter IDs 1 and 2, enter the following command. Packets that match the filters in both filter IDs are stored in the capture buffer.

ServerIronADX(debug-filter)# apply "1 and 2"

ServerIronADX(debug-filter)#show 1

Filter-ID: 1MAC filters:

Src MAC : ANYDest MAC : ANYMAC Type : ANY

IP filters:Src IP : 192.168.8.1Dest IP : 192.168.8.222Protocol : ANY

TCP filters:Src port: ANYDest port: 80Flags : None

UDP filters:Src port: ANYDest port: ANY

HTTP filters:Url : ANYCookie : ANY

Pattern filters:Pattern : ANY



This is useful to create more complex filtering rules. A single filter ID is not able to cover a communication from host A to host B because it is necessary to cover the "flow" from host A to host B and the "flow" from host B to host A.

Example:

Create a filter logic to look for every packet of the communication in between the client with IP 192.168.8.1 and the virtual server with IP 192.168.8.222 at port 80:

ServerIronADX(debug-filter)# sp 1ServerIronADX(debug-filter-spec-1)#ip src 192.168.8.1ServerIronADX(debug-filter-spec-1)#ip dest 192.168.8.222ServerIronADX(debug-filter-spec-1)#tcp dest 80ServerIronADX(debug-filter-spec-1)#exitServerIronADX(debug-filter)#sp 2ServerIronADX(debug-filter-spec-2)#ip dest 192.168.8.1ServerIronADX(debug-filter-spec-2)#ip src 192.168.8.222ServerIronADX(debug-filter-spec-2)#tcp src 80ServerIronADX(debug-filter-spec-2)#exitServerIronADX(debug-filter)# apply "1 or 2"

The filter ID 1 is going to hit for all packets from the client to the virtual server and filter ID 2 is going to hit for the return traffic. One of these filter IDs need to be true to be sure it is part of the communication we are looking for.

It is also possible to create more complex filter expressions as shown below:

To apply filter IDs 1, 2, and 3 so that packets must match the filters in 1 and match the filters in either 3 or 4, enter the following command:

ServerIronADX(debug-filter)#apply "(1 and (3 or 4))"

To view the currently applied expressions:

ServerIronADX(debug-filter-all-all)#show applyFilter ID apply expression: ( 1 and ( 3 or 4 ) )

Syntax: show apply

Start Capturing Process

You are able to start the capturing process as soon as you have done all the steps mentioned above. Once you start the packet capture utility, filtered packets are stored in the capture buffer and are available for viewing until you restart the utility.

To start the packet capture utility, enter the following command:

ServerIronADX (debug-filter)# start

Syntax: start

The packet capturing process will run until the configured buffer is full or until it is stopped manually.



Stop Capturing Process

You can stop the packet capture utility with the following command:

ServerIronADX(debug-filter)# stopNumber of packets captured: 126

Syntax: stop

View Captured Packets

First of all you have to select one of the places where packets are getting captured at. JetCore based devices do offer two locations:

• MP = Management Processor

• BP = Barrel Processor

Use the view command to select the processor you would like to choose:

To select BP 2 of the WSM module in slot 1:

ServerIronADX(debug-filter)# view bp 1 2ServerIronADX(debug-filter-1-2)#

To select the MP:

ServerIronADX(debug-filter)# view mpServerIronADX(debug-filter-mp)#

Syntax: view [mp | bp slot-number cpu-number]

You now have multiple options and you might want to use the summary command to see a summary of all packets captured at the chosen location.

Syntax: summary

It is also possible to have a close look at a single packet using the hex-dump or ascii-dump command:

Syntax: ascii-dump packet-number

Syntax: hex-dump packet-number

The example below includes some example outputs which might help to understand how to use the commands.



"debug filter" example

Test network:client (192.168.8.100) ---- port 15 (192.168.8.1) ServerIron ADX (192.168.9.1) port 3 --- (192.168.9.101) real server

Virtual server @ ADX: 192.168.8.222 offering HTTP service

ADX real and virtual server configuration:

server real rs101 192.168.9.101port httpport http url "HEAD /"!!server virtual vs222 192.168.8.222port httpbind http rs101 http

Task: Get a packet capture of an HTTP request coming from the client IP 192.168.8.100 to the virtual server 192.168.8.222 including the packets going to the real server 192.168.9.101.

The source IP of the client request is 192.168.8.100 and the destination TCP port is 80. The backend traffic is as well using the client IP 192.168.8.100 because we do not have source-nat configured. The real servers service port is 80 as well. The return/reply traffic is going to use 192.168.8.100 as destination IP and it is using the source TCP port 80.

Filters to configure:

1. from source IP 192.168.8.100 to destination port 80 TCP

2. to destination IP 192.168.8.100 from source port 80 TCP

Interesting traffic will hit the the first or second filter.

CLI commands/outputs and comments:

Enter debug filter utility:telnet@ServerIronADX 1000>enaNo password has been assigned yet...telnet@ServerIronADX 1000#debug filter

Configure buffer-size and packet-size to store in buffer:telnet@ServerIronADX 1000(debug-filter)#buffer-size 4096telnet@ServerIronADX 1000(debug-filter)#packet-size whole

Create filter 1 and filter 2:

telnet@ServerIronADX 1000(debug-filter)#sp 1telnet@ServerIronADX 1000(debug-filter-spec-1)#resettelnet@ServerIronADX 1000(debug-filter-spec-1)#ip src 192.168.8.100telnet@ServerIronADX 1000(debug-filter-spec-1)#tcp dest 80telnet@ServerIronADX 1000(debug-filter-spec-1)#exittelnet@ServerIronADX 1000(debug-filter)#sp 2telnet@ServerIronADX 1000(debug-filter-spec-2)#resettelnet@ServerIronADX 1000(debug-filter-spec-2)#ip dest 192.168.8.100telnet@ServerIronADX 1000(debug-filter-spec-2)#tcp src 80telnet@ServerIronADX 1000(debug-filter-spec-2)#exit



Apply filters using OR as operator:telnet@ServerIronADX 1000(debug-filter)#apply 1or2

Start capturing process:telnet@ServerIronADX 1000(debug-filter)#start

SENT REQUEST FROM TEST CLIENT 192.168.8.100 NOW

Stop capturing process:telnet@ServerIronADX 1000(debug-filter)#stop

Check ALL BPs to find the BP responsible for the test client:telnet@ServerIronADX 1000(debug-filter)#view bp 1 1telnet@ServerIronADX 1000(debug-filter-1-1)#sumtelnet@ServerIronADX 1000(debug-filter-1-1)#view bp 1 2telnet@ServerIronADX 1000(debug-filter-1-2)#sumtelnet@ServerIronADX 1000(debug-filter-1-2)#view bp 1 3telnet@ServerIronADX 1000(debug-filter-1-3)#sum

NOTHING SO FAR - CHECK THE NEXT AND LAST PROCESSOR TALKING ABOUT THE ADX1016-4:

telnet@ServerIronADX 1000(debug-filter-1-3)#view bp 1 4telnet@ServerIronADX 1000(debug-filter-1-4)#sum

Number of packets captured: 20

pkt:1 IN len:112 TCP :3881 ->80 Seq:4047880146 Ack SYNpkt:2 OUTlen:138 TCP :3881 ->80 Seq:4047880146 Ack SYNpkt:3 IN len:112 TCP :80 ->3881 Seq:2434401979 Ack:4047880147 SYN ACKpkt:4 OUTlen:138 TCP :80 ->3881 Seq:2434401979 Ack:4047880147 SYN ACKpkt:5 IN len:106 TCP :3881 ->80 Seq:4047880147 Ack:2434401980 ACKpkt:6 OUTlen:132 TCP :3881 ->80 Seq:4047880147 Ack:2434401980 ACKpkt:7 IN len:152 TCP :3881 ->80 Seq:4047880147 Ack:2434401980 ACK PSHpkt:8 OUTlen:178 TCP :3881 ->80 Seq:4047880147 Ack:2434401980 ACK PSHpkt:9 IN len:106 TCP :80 ->3881 Seq:2434401980 Ack:4047880199 ACKpkt:10 OUTlen:132 TCP :80 ->3881 Seq:2434401980 Ack:4047880199 ACKpkt:11 IN len:423 TCP :80 ->3881 Seq:2434401980 Ack:4047880199 ACK PSHpkt:12 OUTlen:449 TCP :80 ->3881 Seq:2434401980 Ack:4047880199 ACK PSHpkt:13 IN len:106 TCP :3881 ->80 Seq:4047880199 Ack:2434402303 ACKpkt:14 OUTlen:132 TCP :3881 ->80 Seq:4047880199 Ack:2434402303 ACKpkt:15 IN len:106 TCP :3881 ->80 Seq:4047880199 Ack:2434402303 ACK FINpkt:16 OUTlen:132 TCP :3881 ->80 Seq:4047880199 Ack:2434402303 ACK FINpkt:17 IN len:106 TCP :80 ->3881 Seq:2434402303 Ack:4047880200 ACK FINpkt:18 OUTlen:132 TCP :80 ->3881 Seq:2434402303 Ack:4047880200 ACK FINpkt:19 IN len:106 TCP :3881 ->80 Seq:4047880200 Ack:2434402304 ACKpkt:20 OUTlen:132 TCP :3881 ->80 Seq:4047880200 Ack:2434402304 ACK

The test client hits BP 1 4 and the summary is showing 20 packets related to the test request. Packet #1 is the incoming TCP SYN packet, packet #2 is the same SYN packet but it is behind the ServerIron (going to the real server). Each packet is visibile twice because it exists before and after the ServerIron (before SLB and after SLB).

The client HTTP request is part of packet #7 (after the 3-way handshake):

telnet@ServerIronADX 1000(debug-filter-1-4)#ascii 7

Packet 7 captured at Oct 26 17:00:24 ; Packet size is 152(0x0098) bytesIn port: 15fpga optimized: No



Ethernet Version IIAddress: 0024.81f7.2f8f ---> 021b.ed3c.cb60Ethernet II Protocol Type: IP

Internet ProtocolVersion(MSB 4 bits): 4Header length(LSB 4 bits): 5 (32-bit word)Service Type: 0x00Total length: 92 (Octets)Fragment ID: 7207Flags summary: 0x40

0... .... = Reserved.1.. .... = Do not fragment..0. .... = Last fragmentFragment offset(LSB 13 bits): 0 (0x00)

Time to live: 128 seconds/hopsIP protocol type: TCP (0x06)Checksum: 0x4be2IP address: 192.168.8.100 ---> 192.168.8.222No option

Transmission Control ProtocolPort 3881 ---> 80Sequence Number: 4047880147Acknowledgement Number: 2434401980Header Length(MSB 4 bits): 5 (32-bit word)Reserved(LSB 4 bits): 0Code: 0x18

RES: 0... ....CON: .0.. ....URG: ..0. ....ACK: ...1 ....PSH: .... 1...RST: .... .0..SYN: .... ..0.FIN: .... ...0

Window: 64000Checksum: 0xe90fUrgent Pointer: 0x0000

Data:0000: 47 45 54 20 2f 20 48 54 54 50 2f 31 2e 31 0d 0a | GET / HTTP/1.1..0010: 48 6f 73 74 3a 20 31 39 32 2e 31 36 38 2e 38 2e | Host: 192.168.8.0020: 32 32 32 0d 0a 41 63 63 65 70 74 3a 20 2a 2f 2a | 222..Accept: */*0030: 0d 0a 0d 0a 00 00 00 00 00 00 00 00 00 00 | ..............

The packet arrived via port 15 (client facing) and the IP header is showing the following:

• source IP: 192.168.8.100

• destination IP: 192.168.8.222



This is a packet coming from the client to the virtual server. Packet #8 is the same packet BUT on the way to the real server (after SLB):

telnet@ServerIronADX 1000(debug-filter-1-4)#ascii 8

Packet 8 captured at Oct 26 17:00:24 ; Packet size is 178(0x00b2) bytesOut port: 3fpga optimized: No

Ethernet Version IIAddress: 001b.ed3c.cb62 ---> 021b.ed3c.cb60Ethernet II Protocol Type: IP

Internet ProtocolVersion(MSB 4 bits): 4Header length(LSB 4 bits): 5 (32-bit word)Service Type: 0x00Total length: 92 (Octets)Fragment ID: 7207Flags summary: 0x40

0... .... = Reserved.1.. .... = Do not fragment..0. .... = Last fragmentFragment offset(LSB 13 bits): 0 (0x00)

Time to live: 128 seconds/hopsIP protocol type: TCP (0x06)Checksum: 0x4be2IP address: 192.168.8.100 ---> 192.168.9.101No option

Transmission Control ProtocolPort 3881 ---> 80Sequence Number: 4047880147Acknowledgement Number: 2434401980Header Length(MSB 4 bits): 5 (32-bit word)Reserved(LSB 4 bits): 0Code: 0x18

RES: 0... ....CON: .0.. ....URG: ..0. ....ACK: ...1 ....PSH: .... 1...RST: .... .0..SYN: .... ..0.FIN: .... ...0

Window: 64000Checksum: 0xe90fUrgent Pointer: 0x0000

Data:0000: 47 45 54 20 2f 20 48 54 54 50 2f 31 2e 31 0d 0a | GET / HTTP/1.1..0010: 48 6f 73 74 3a 20 31 39 32 2e 31 36 38 2e 38 2e | Host: 192.168.8.0020: 32 32 32 0d 0a 41 63 63 65 70 74 3a 20 2a 2f 2a | 222..Accept: */*0030: 0d 0a 0d 0a 00 00 00 00 00 00 00 00 00 00 00 00 | ................0040: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | ................0050: 00 00 00 00 00 00 00 00 | ........

The packet is leaving via port 3 (real server facing) and the IP header is showing the following:

• source IP: 192.168.8.100

• destination IP: 192.168.9.101

This is a packet coming from the client going to the real server.


Emulating tcpdump using the debug filterC

Helpful tips It is a good practice to RESET a filter ID as soon as you want to define the filter. Filter ID settings do survive until the unit is getting rebooted. A reset ensures the filter is back at the default which implies "match ALL":

telnet@ServerIronADX 1000(debug-filter)#sp 2telnet@ServerIronADX 1000(debug-filter-spec-2)#reset

The ADX is also able to store traces in PCAP format.

The ADX offers up to 256 MB of capturing space.

Emulating tcpdump using the debug filterTo support the emulation of tcpdump using the debug filter, use the packetdump command available in exec and all configuration modes. This command prints captured packets in real time.

For example, to capture packets on all interfaces with specified buffer size, use the following command.

ServerIronADX# packetdump -B 1pkt:1 OUTlen:60 IP:13.24.138.16 ->13.24.138.170 ICMP:Echo Requestpkt:2 OUTlen:60 IP:13.24.138.16 ->13.24.138.170 ICMP:Echo Requestpkt:3 OUTlen:60 IP:13.24.138.16 ->13.24.138.170 ICMP:Echo Requestpkt:4 OUTlen:60 IP:13.24.138.16 ->13.24.138.170 ICMP:Echo Requestpkt:5 OUTlen:60 IP:13.24.138.16 ->13.24.138.170 ICMP:Echo Requestpkt:6 OUTlen:60 MAC:000c.2947.cc02->ffff.ffff.ffff ARP:Requestpkt:7 OUTlen:60 MAC:000c.2947.cc02->ffff.ffff.ffff ARP:Requestpkt:8 OUTlen:60 IP:13.24.138.16 ->13.24.138.170 ICMP:Echo Requestpkt:9 OUTlen:60 IP:13.24.138.16 ->13.24.138.170 ICMP:Echo Requestpkt:10 OUTlen:60 IP:13.24.138.16 ->13.24.138.170 ICMP:Echo Request

Syntax: packetdump parameters

The parameter variable is for the keywords and variables with combination of AND and OR for operands.

Table 50 lists and describes the parameters used with the packetdump command.

TABLE 50 Parameters for the packetdump command

Parameter Description

-B buffer_size Set the buffer size

-s packet_size Set the packet size

src IP_address Set the source IP address

dest dest_IP_address Set the destination IP address

port port_number Set the port number.

tcp src src_port Set the TCP source port

tcp dest dest_port Set the TCP destination port

udp src src_port Set the UDP source port


Displaying global Layer 4 ServerIron ADX configuration C

In the following example of AND and OR operand combinations, all the parameters with AND are stored in one specification and then are applied with OR. In debug terms, the ServerIron ADX creates two specification for the command and applies it as “apply 1or2.”

ServerIronADX# packetdump src 1.1.1.1 and dest 2.2.2.2 and prot 1 and tcp src 80 and udp src 80 or src 4.4.4.4 and dest 3.3.3.3 and prot 2 and tcp src 70 and udp src 70

Displaying global Layer 4 ServerIron ADX configurationTo display global Layer 4 ServerIron ADX configuration information, enter the following command.

Syntax: show server global

Table 51 lists the displayed information.

udp dest dest_port Set the UDP destination port

-w file_name Store captured packets in the specified file name

TABLE 50 Parameters for the packetdump command

Parameter Description

TABLE 51 Global layer 4 configuration information

Field Description

Symmetric Active-Standby HA Parameters You also can display this information separately.

Server Symmetric port The ServerIron ADX port number on which the ServerIron ADX perceives other ServerIron ADXs running Symmetric Active-Standby HA.

Group_id The Symmetric Active-Standby HA group ID. The group ID is always 1 in the current release.

Candidate cnt The number of ports on which the ServerIron ADX perceives a partner ServerIron ADX running Symmetric Active-Standby HA.

Port The TCP/UDP port for which Symmetric Active-Standby HA is enabled.

ServerIronADX(config)#show server global

Server Load Balancing - global parameters Predictor = least-conn Force-deletion = 0 Reassign-threshold = 20 Reassign-limit = 3 Ping-interval = 2 Ping-retries = 4 TCP-age = 30 UDP-age = 5 Sticky-age = 30 TCP-syn-limit = 65535 TCP-total conn = 4233 Unsuccessful conn = 0 ICMP-message = Disabled


Displaying global Layer 4 ServerIron ADX configurationC

Priority The priority for the VIP.

No-rx Information used by Brocade technical support to help resolve Symmetric Active-Standby HA configuration issues.

SLB Parameters

Predictor The load balancing metric in effect on the ServerIron ADX. The predictor can be one of the following:• least-conn (least connections)• round-robin• weighted-round-robin • weighted• enhanced-weighted • least-local-conn (least local connections)• least-local-sess (least local sessions)The default is least-conn.You can assign these metrics on a global basis and an individual virtual server basis. For more information, refer to “Load-balancing predictor” on page 28.To change the predictor (globally or locally), refer to “Changing the Load-Balancing Predictor Method” on page 42.

Force-deletion The state of the force shutdown option. This option immediately shuts down a server or service instead of waiting for existing connections to end before shutting the server or service down. The state can be one of the following:• 0 – Disabled• 1 – Enabled

Reassign-threshold The number of contiguous inbound TCP-SYN packets sent to the server that the server has not responded to.The TCP SYN-ACK counter increments only when acknowledgments are not received. Each time an expected TCP SYN-ACK is received, the counter is cleared. The default reassign threshold is 20 unacknowledged TCP SYN-ACKs. The value can be from 6 through 4000. To change the reassign threshold, refer to “Reassign threshold” on page 279

NOTE: You can modify this parameter to help minimize vulnerability to TCP SYN attacks.

Reassign-limit The number of missed TCP SYN packets the ServerIron ADX will accept before moving an inbound connection attempt to another server.

Layer 3 Health Check Parameters

Ping-interval How often the ServerIron ADX sends a Layer 3 IP ping to test the basic health and reachability of the real servers. When enabled, this parameter specifies the interval for the pings. To change the interval, refer to “Modifying the ping interval and ping retries” on page 213.

Ping-retries The number of times that the ServerIron ADX resends a ping to a real server that is not responding. Allowed values are from 2 through 10, and the default is 4. To change this parameter, refer to “Modifying the ping interval and ping retries” on page 213.If the server still does not respond after the last retry, the ServerIron ADX marks the server FAILED and removes it from the load balancing rotation.

TABLE 51 Global layer 4 configuration information (Continued)

Field Description


Displaying global Layer 4 ServerIron ADX configuration C

Global TCP/UDP Parameters

TCP-age The number of minutes the ServerIron ADX allows a TCP connection to remain unused before closing the connection. The default is 30. To change this parameter, refer to “Configuring TCP age” on page 301.The value shown here is the global value. You can override this value for an individual TCP/UDP port by modifying its port profile. Refer to “Overriding the global TCP or UDP age” on page 248.

UDP-age The number of minutes the ServerIron ADX allows a UDP connection to remain unused before closing the connection. The default is 5. To change this parameter, refer to “Configuring UDP age” on page 301.The value shown here is the global value. You can override this value for an individual TCP/UDP port by modifying its port profile. Refer to “Overriding the global TCP or UDP age” on page 248.

Sticky-age The number of minutes a sticky server connection can remain inactive before aging out. The default is 5.

TCP-syn-limit The maximum number of TCP SYN connections per second the ServerIron ADX is allowed to send to the real server. The default is 65535.You can guard against TCP SYN attacks by changing this parameter to a lower value. Refer to “Limiting the maximum number of TCP SYN requests” on page 146.

TCP Connections Counters

TCP-total conn The total number of TCP connections the ServerIron ADX is currently managing.

Unsuccessful conn The number of client requests for a TCP port that the ServerIron ADX could not fulfill because the server was busy or down, or because the port was not configured on the server.

ICMP Message Feature State

ICMP-message The state of the ICMP message feature. The state can be one of the following:• Disabled – The ServerIron ADX does not send ICMP “Destination

Unreachable” messages to a client that requests an HTTP port that is on a busy or down server or that is not configured on the server. This is the default.

• Enabled – The ServerIron ADX sends ICMP “Destination Unreachable” messages to clients when the requested HTTP port is not available or not configured.

To change the state of this feature, refer to “Sending ICMP Port Unreachable or Destination Unreachable messages” on page 150.

TABLE 51 Global layer 4 configuration information (Continued)

Field Description


Displaying real server information and statisticsC

Displaying real server information and statistics

Using the show server real commandUse the show server real command to view real IP addresses as well as configuration information and basic statistics for all the real servers configured on the ServerIron ADX.

To display configuration information for a specific real server, enter the show server real command using its server name or IP address such as in the following example:

Syntax: show server real server-name | ip-address

The server-name variable specifies the real server by name. Alternatively, the ip-address variable may be used to specify the real server by its IP address.

ServerIronADX 1000(config)#show server real r6Real Servers Info========================State(St) - ACT:active, ENB:enabled, FAL:failed, TST:test, DIS:disabled, UNK:unknown, UNB:unbind, AWU:await-unbind, AWD:await-delete HLD:held-down

Name: r6 State: Active Cost: 0 IP:400::457: 1Mac: 0000.855d.e2cd Weight: 1/1 MaxConn: 2000000SrcNAT: not-cfg, not-op DstNAT: not-cfg, not-op Serv-Rsts: 0Rx throughput: 190 Kbps Tx throughput: 340 Kbpstcp conn rate:udp conn rate = 9:0, max tcp conn rate:max udp conn rate = 9:0BP max local conn configured No: 0 0 0 0 0 0BP max conn percentage configured No: 0 0 0 0 0 0Use local conn : NoSIP current TCP connections = 0

Port St Ms CurConn TotConn Rx-pkts Tx-pkts Rx-octet Tx-octet Reas---- -- -- ------- ------- ------- ------- -------- -------- ----default UNB 0 0 0 0 0 0 0 0http ACT 0 20 970 4398 4847 563498 607932 0

Server Total 0 970 4398 4847 563498 607932 0


Displaying real server information and statistics C

Table 52 describes the information returned by the show server real command.

TABLE 52 Real server information

Field Description

Server State Codes

State (St) The possible values for the server state. The state of each real server is shown by the State field, described in this table.

General Server Parameters

Name The name of the real server. This is the name you assigned to the server when you configured it on the ServerIron ADX.

State The state of the real server, based on Layer 3 health checks. The state can be one of the following states, also listed next to "Server State" displayed at the top of the show server real command outout:• ACT: Active• ENB: Enabled• FAL: Failed• TST: Test• DIS: Disabled• UNK: Unknown• UNB: Unbind• AWU: Await-unbind• AWD: Await-delete• HLD: Held-down

NOTE: The value in this field is based on the results of Layer 3 health checks, if enabled. The real server state can also be seen in the State column in the show server session command output. To display the server state based on Layer 3 health checks, refer to the State field in the show server session command output.

Cost The hop cost to reach the remote or cache server.

Mac The real server MAC address or next hop MAC address for remote servers.

Wt The weight assigned to this server. The weight applies only if the predictor (load balancing method) is “weighted”. Refer to “Unbinding all application ports from virtual servers” on page 158.

Max-conn The maximum number of client connections that the ServerIron ADX will manage for the server. A connection consists of two sessions, the client-to-server session and the server-to-client session.By default, the ServerIron ADX allows up to 500,000 connections (one million sessions) on a server. If you need to lower the maximum number of connections the ServerIron ADX will manage, refer to “Configuring the maximum number of active sessions” on page 298.

SrcNAT The configured and operational states of the source NAT feature. The two states are separated by a colon (:). The configured state is shown first, followed by the operational state. Each state can have one of the following values:• 0 – Disabled• 1 – Enabled



DestNAT The configured and operational states of the destination NAT feature. The two states are separated by a colon (:). The configured state is shown first, followed by the operational state. Each state can have one of the following values:• 0 – Disabled• 1 – Enabled

Serv-Rsts Number of resets sent by the real server for a TCP SYN packet forwarded by ServerIron ADX.

Rx throughput Rate at which packets are received expressed in Kbps.

Tx throughput Rate at which packets are transmitted expressed in Kbps.

tcp conn rate Rate at which the server receives TCP connections.

max tcp conn rate The maximum rate of TCP connections received by the server.

udp conn rate Rate at which a real or remote server receives UDP connections.

BP max local conn configured No Not currently supported/valid for ServerIron ADX.

BP max conn percentage configured No

Not currently supported/valid for ServerIron ADX.

Use local conn Not currently supported/valid for ServerIron ADX.

SIP current TCP connections The number of current TCP connections to the SIP real server.

TABLE 52 Real server information (Continued)

Field Description



Using the show server real detail commandUse the show server real detail command to view information about a specified real server and the various ports configured on this server.

ServerIronADX 1000(config)#sh serv real rs1 detailReal Servers Info========================State(St) - ACT:active, ENB:enabled, FAL:failed, TST:test, DIS:disabled, UNK:unknown, UNB:unbind, AWU:await-unbind, AWD:await-delete HLD:held-downName: rs1 State: Enabled Cost: 0 IP:192.168.5.3: 1Mac: Unknown Weight: 1/1 MaxConn: n/aSrcNAT: not-cfg, not-op DstNAT: not-cfg, not-op Serv-Rsts: 0Mem: Server: 2e09f26a Dynamic: NoFail port exist: YRx throughput: 804 Kbps Tx throughput: 1810 Kbpstcp conn rate:udp conn rate = 10:20, max tcp conn rate:max udp conn rate = 20:30BP max local conn configured No: 0 0 0 0 0 0BP max conn percentage configured No: 0 0 0 0 0 0Use local conn : NoSIP current TCP connections = 0Port St Ms CurConn TotConn Rx-pkts Tx-pkts Rx-octet Tx-octet Reas

---- -- -- ------- ------- ------- ------- -------- -------- ----

default UNB 0 0 0 0 0 0 0 0

max_conn = 2000000 fail time = 0, Vir IP 0.0.0.0

tcp conn rate:udp conn rate = 0:0, max tcp conn rate:max udp conn rate =

:0

SIP TCP Current Connections = 0

Rx throughput: 0 Kbps Tx throughput: 0 Kbps

BP max local conn configured No: 0 0 0 0 0 0

BP max conn percentage configured No: 0 0 0 0 0 0

Use local conn : No



Table 53 describes the information returned by the show server real detail command. The fields apply to all the TCP/UDP ports on the real servers.

For DNS, HTTP, and RADIUS ports, the server-specific health check information for the port is listed under the port’s statistics. For information about the health check parameters, refer to “Changing HTTP keepalive method, value, and status codes” on page 232.

TABLE 53 Real server detail information

Field Description

Port The TCP/UDP port name or number. This field can have one of the following values:• default• dns – The well-known name for port 53• ftp – The well-known name for port 21. (Ports 20 and 21 both are

FTP ports but on the ServerIron ADX, the name “ftp” corresponds to port 21.)

• http – The well-known name for port 80• imap4 – The well-known name for port 143• ldap – The well-known name for port 389• nntp – The well-known name for port 119• ntp – The well-known name for port 123• pop2 – The well-known name for port 109• pop3 – The well-known name for port 110• radius – The well-known name for udp port 1812• smtp – The well-known name for port 25• snmp – The well-known name for port 161• ssl – The well-known name for port 443• telnet – The well-known name for port 23• tftp – The well-known name for port 69• number – The port number, if the port is not one of those listed

above

St The state of the port. The state can be one of the following:• enabled• failed• test• suspect• graceful shutdown• active• unbnd

NOTE: If the state is unbnd, you have not bound the port to a virtual server port.



Ms The master port state. This field applies only to track ports and to ports to which you have bound other TCP/UDP ports in many-to-one configurations.• For track ports, the state of the master port. When a port is

configured to track a master port, the ServerIron ADX sends a client’s request for the tracking port to the same real server as the master port. Refer to “Track port group function” on page 74 and “TCP/UDP application groups” on page 531. The example show real server command output shown above assumes that port 500 is tracked by port 600. If port 500’s state changes, port 600’s state also changes to match.

• For many-to-one TCP/UDP port binding, the state of the port that is translated in the port binding between the real server and the virtual server. The ports that are not translated follow the state of the port that is translated. Refer to “Multiple port binding” on page 98. In the example show real server command output shown above, assume that port 70 is untranslated and follows the state of port http. If the http port’s state changes, port 70’s state also changes to match.

This field can have one of the following values for the types of ports listed above:• 1 – Enabled• 2 – Failed• 3 – Test• 4 – Suspect• 5 – Graceful shutdown• 6 – ActiveFor all other types of ports, the value is always 0.

CurConn The number of client connections currently on the server. A connection consists of two sessions, the client-to-server session and the server-to-client session.

TotConns The number of client connections on the server since the ServerIron ADX was last booted. A connection consists of two sessions, the client-to-server session and the server-to-client session.

Rx-pkts The number of packets the ServerIron ADX has received from the server.

Tx-pkts The number of packets the ServerIron ADX has sent to the server.

Rx-octet The number of octets (bytes) the ServerIron ADX has received from the server.

Tx-octet The number of octets (bytes) the ServerIron ADX has sent to the server.

Reas The number of times the ServerIron ADX has reassigned the connection to another server in the rotation because the server that is in use has not responded to two contiguous TCP SYNs from the client. When this occurs, the ServerIron ADX directs the client to another server upon receiving the third SYN from the client.

NOTE: Windows 98 sends two TCP SYNs for each connection attempt.

NOTE: This statistic does not apply to SwitchBack (Direct Server Return).

Rx throughput Rate at which packets are received expressed in Kbps.

Tx throughput Rate at which packets are transmitted expressed in Kbps.

TABLE 53 Real server detail information (Continued)

Field Description



Displaying real server keepalive statisticsUse the show server real keepalive command to view real server keepalive statistics:

Syntax: show server real keepalive port | server-name

Displaying real server connections per second statisticsUse the show server connection command to view real server connections per second (CPS):

Syntax: show server connection

ServerIronADX 1000#show server real keepalive 8080 rs1

Port index 255Real Server Name: rs1 Real Port Status = ACTIVESlot valid = TRUE IP: 135.200.41.63real port proto = TCP Real port no = 8080Keepalive Enabled Keepalive port proto = TCP/8080TCP request = 3518128 TCP response = 318805TCP response timeout = 19HTTP URL = “GET/health.html”HTTP sent = 318805 Received ok = 292385HTTP received error = 26394 Received timeout = 0HTTP wait for response = FALSE Status Code = 200Server close = 10 Current sent = 0Bring port down = 9 Total retries = 14TCP RTT = 14000 us Appl RTT = 3300 usNext slot index = 193

ServerIronADX 1000#show server connection

Avail. Sessions on MP = 999888 Total Sessions on MP = 1000000

bp-1 Avail. Session = 1999868 Total Sessions = 2000000bp-2 Avail. Session = 1999872 Total Sessions = 2000000bp-3 Avail. Session = 1999872 Total Sessions = 2000000bp-4 Avail. Session = 1999868 Total Sessions = 2000000

Total C->S Conn = 97920 Total S->C Conn = 0Total Reassign = 0 Unsuccessful Conn = 0last conn rate = 29 max conn rate = 37last TCP attack rate = 0 max TCP attack rate = 0SYN def RST = 0 SYN flood = 0Server State - 1:enabled, 2:failed, 3:test, 4:suspect, 5:grace_dn, 6:active

Real Server State CurrConn TotConn CurrRate MaxRate

rs1 1 0 0 0 0r6 6 240 97920 30 40


Displaying virtual server information and statistics C

Displaying virtual server information and statisticsUse the show server virtual command to view information about the virtual servers configured on the ServerIron ADX.

To display configuration information for a specific virtual server, enter the show server virtual command using its server name such as in the following example:

Syntax: show server virtual Virtual-server-name|Virtual server IP address virtual-port

The Virtual-server-name variable specifies the virtual server by name. Alternatively, the Virtual server IP address variable can be used to specify the IP address of the virtual server. The virtual-port variable can be used to specify a particular port on the virtual server. For more information, see “Displaying a list of failed servers” on page 518.

ServerIronADX 1000(config)#show server virtual v6Virtual Servers Info

Name: v6 State: Enabled IP:400::456: 1Pred: round-robin ACL-Id: 0 TotalConn: 970VIP state: healthyRx throughput: 1900 Kbps Tx throughput: 3400 KbpsConnections per Second 0

Port State Sticky Concur Proxy DSR CurConn TotConn PeakConn---- ----- ------ ------ ----- --- ------- ------- --------

default enabled NO NO NO NO 0 0 0http enabled NO NO NO NO 0 970 68ftp enabled NO NO NO NO 0 0 0telnet enabled NO NO NO NO 0 0 0


Displaying virtual server information and statisticsC

Table 54 describes the different types of information that can be viewed using the show virtual server command:

TABLE 54 Virtual server information

Field Description

General Server Parameters

Name The name of the virtual server. This is the name you assigned to the server when you configured it on the ServerIron ADX.

State The status of the virtual server. The status can be one of the following:• Enabled• Disabled

IP The IP address of the virtual server. If you configured a host range of VIPs on the server, the number following the IP address (after the colon) is the number of hosts on the server. In the example above, the VIP has a host range of 4 addresses.

Predictor The load balancing predictor the ServerIron ADX uses to balance traffic among the real servers bound to this virtual server. The predictor can be one of the following:• least-conn • round-robin • weighted-round-robin• weighted • enhanced-weightedYou can assign these metrics on a global basis and an individual virtual server basis. For more information, refer to “Load-balancing predictor” on page 28.To change the predictor (globally or locally), refer to “Changing the Load-Balancing Predictor Method” on page 42.

ACL-Id The access control list Id is the ACL number that identifies the ACL that the ServerIron ADX allows to restrict clients access to the VIP, either allowing or denying access.

Tot-Conn The number of client connections on the server since the ServerIron ADX was last booted or restarted. A connection consists of two sessions, the client-to-server session and the server-to-client session.

VIP state

Rx throughput The rate of throughput received in Kbps.

Tx throughput The rate of throughput transmitted in Kbps.

Connections per second

The connection rate measured in seconds.

Dynamic A statistic used by Brocade technical support.


Displaying virtual server information and statistics C

Sym Information for Symmetric Active-Standby HA. The following information is displayed:• group – The Symmetric Active-Standby HA group number.• state – State 3 means the VIP is inactive. State 5 means the VIP is active.• priority – The Symmetric Active-Standby HA priority configured on the ServerIron

ADX.• keep – The number of times an Symmetric Active-Standby HA backup has failed to

communicate with the active ServerIron ADX. By default, the counter is incremented by 1 every 400 milliseconds the backup ServerIron ADX is late responding to the active ServerIron ADX’s keepalive message. The counter is reset to 0 each time the backup ServerIron ADX replies to a keepalive message. If the counter goes higher than the maximum number allowed (20 by default, thus 8 seconds), the standby ServerIron ADX takes over as the new active ServerIron ADX. Normally, this field almost always contains 0.

NOTE: This field is applicable only on the active ServerIron ADX.• dyn priority/factor – The current dynamically set priority and the decrement value.

In this example, an application has failed a health check, so the dynamic priority is 20 instead of 30. The decrement value is 10. If the priority and dyn priority values match, then all the VIP’s applications that are configured for Symmetric Active-Standby HA are responding to their health checks.

• Activates – The number of times this ServerIron ADX has become the active ServerIron ADX.

• Inactive – The number of times this ServerIron ADX has changed from being the active ServerIron ADX.

• Best-standby-mac – The MAC address of the backup ServerIron ADX with the second-highest priority. This ServerIron ADX will become the active ServerIron ADX if a failover occurs.

For more information about Symmetric Active-Standby HA, refer to “Symmetric Active-Standby HA” on page 399.

TCP/UDP Port Information and Statistics

Port The TCP/UDP port name or number. This field can have one of the following values:• default• dns –The well-known name for port 53• ftp – The well-known name for port 21. (Ports 20 and 21 both are FTP ports but on

the ServerIron ADX, the name “ftp” corresponds to port 21.)• http – The well-known name for port 80• imap4 – The well-known name for port 143• ldap – The well-known name for port 389• nntp – The well-known name for port 119• ntp – The well-known name for port 123• pop2 – The well-known name for port 109• pop3 –The well-known name for port 110• radius – The well-known name for udp port 1812• radiuso – UDP port 1645, which is used in some older RADIUS implementations

instead of port 1812• smtp – The well-known name for port 25• snmp – The well-known name for port 161• ssl – The well-known name for port 443• telnet – The well-known name for port 23• tftp – The well-known name for port 69• number – The port number, if the port is not one of those listed above

TABLE 54 Virtual server information (Continued)

Field Description


Displaying a list of failed serversC

Displaying a list of failed serversUse the show server failed command to display all servers that are not in Active or Disabled state. Only servers in the failed state are included in the display.

Example

SLB-ServerIronADX#show server failedReal servers in Failed state:Total failed servers: 3Name: MyServer01 IP:192.168.160.91 State: EnabledName: MyServer02 IP:192.168.160.92 State: EnabledName: MyServer03 IP:192.168.160.93 State: Enabled

Syntax: show server failed

State The state of the port. The state can be one of the following:• enabled• failed• test• suspect• graceful shutdown• active• unbnd

NOTE: If the status is unbnd, you have not bound the port to a real server port.

Sticky Whether the port is “sticky”. When a port is sticky, the ServerIron ADX uses the same real server for multiple requests from the same client for the port. For non-sticky ports, the ServerIron ADX load balances the requests and thus does not necessarily send them all to the same real server.This parameter can have one of the following values:• NO • YESFor more information, refer to “TCP/UDP application groups” on page 531.

Concur Whether the port is configured for concurrent connections. A port configured to allow concurrent connections can have more than one connection open to the same client at the same time.For more information, refer to “TCP/UDP application groups” on page 531.


TotConn The number of client connections on the server since the ServerIron ADX was booted. A connection consists of two sessions, the client-to-server session and the server-to-client session.

PeakConn The highest number of connections the VIP has had at the same time.

TABLE 54 Virtual server information (Continued)

Field Description


Displaying a list of failed ports C

Displaying a list of failed portsUse the show server port failed command to display all server ports that are not in Active or Disabled state. It also shows the servers to which the ports belong.

Example

SLB-ServerIronADX#show server port failedReal ports in Failed state:Total failed servers:3 Total failed ports:7Name: MyServer01 IP:192.168.160.91 State: EnabledPort http: FailedPort 8081: FailedPort ftp: FailedName: MyServer02 IP:192.168.160.92 State: EnabledPort 8082: FailedPort http: FailedName: MyServer03 IP:192.168.160.93 State: EnabledPort 8083: FailedPort http: Failed

Syntax: show server port failed

Displaying port-binding information

Using the show server bind commandTo display port-binding information, enter the following command.


The display lists the port bindings for each virtual server configured on the ServerIron ADX. The first row of information for each virtual server lists the virtual server name and VIP. The following rows list the TCP/UDP ports configured on the virtual server and the real servers and port names or numbers to which each port is bound.

In the example, two virtual servers are configured on the ServerIron ADX, v100 and v105. The first set of rows in the example output is for virtual server v100, with VIP 10.157.23.100.

SLB-ServerIronADX#show server bind

http -------> s43: 10.157.23.43, http s60: 10.157.23.60, 8080 ftp -------> s43: 10.157.23.43, ftp s60: 10.157.23.60, ftp 70 -------> s43: 10.157.23.43, 70 s60: 10.157.23.60, 70Virtual Server Name: v105, IP: 10.157.23.105 telnet -------> s60: 10.157.23.60, 300 ftp -------> s60: 10.157.23.60, 200 http -------> s60: 10.157.23.60, 100 dns -------> s60: 10.157.23.60, 400 tftp -------> s60: 10.157.23.60, 500


Displaying port-binding informationC

The rows below the first row list the real servers and ports to which the virtual server’s ports are bound. The rows are grouped by port type. The first two rows after the first row in the example above list the port bindings for the virtual server’s HTTP port. In this case, the virtual server is bound to an HTTP port on two real servers, s43 and s60. The port name or number on the real server is listed after the real server’s IP address. In this example, the HTTP port to which v100 is bound on s43 is "http", which is the well-known name for the port. The virtual server’s HTTP port is bound to port 8080 on real server s60.

Using the show server session commandYou can also display port-binding information by entering the show server session command.

Syntax: show server session

Table 55 lists the displayed information for bound ports.

TABLE 55 Field descriptions for the show server session command

Field Description

Global Statistics

Avail. Sessions The number of sessions that are still available for use. By default, the ServerIron ADX is configured to allow the maximum number of sessions it can support. If you need to decrease the number of sessions supported, refer to “Configuring the maximum number of active sessions” on page 298.

Total Sessions The number of sessions that are currently in use.

Total C->S Conn The number of connections initiated by clients.

Total S->C Conn The number of connections initiated by servers. Generally this value is 0 unless the client is using FTP or another application that causes the server to initiate connections.

SLB-chassis#rconsole 1 1SLB-chassis1/1#show server session

Avail. Sessions = 1999998 Total Sessions = 2000000Hash size = 200001

Total C->S Conn = 0 Total S->C Conn = 0Total Reassign = 0 Unsuccessful Conn = 0Server State - 0: diasbled, 1:enabled, 2:failed, 3:test, 4:suspect, 5:grace_dn, 6:active

Real Server St CurrConn TotConn TotRevConn CurrSess PeakConn

rs1 1 0/0/0 0 0 0 0


Displaying port-binding information C

Total Reassign The number of unacknowledged TCP SYN-ACKs on all the real servers combined. When a server reaches the maximum number of unacknowledged TCP SYN-ACKs allowed by the ServerIron ADX (the reassign threshold), the ServerIron ADX marks that server FAILED and removes it from the load balancing rotation.The TCP SYN-ACK counter increments only when acknowledgments are not received. Each time an expected TCP SYN-ACK is received from a real server, the counter is cleared for that server, thus reducing the total count. For more information, refer to “Reassign threshold” on page 279.

NOTE: This statistic does not apply to SwitchBack (Direct Server Return).

Unsuccessful Conn The number of connection attempts by clients or servers that were unsuccessful.

Fast-aged: total If the fast-age threshold is configured, the total number of sessions that were aged out because the number of free sessions dropped below the fast-age threshold, in addition to the number of these sessions that were aged out in the last 60 seconds.

Random-aged: total If the random threshold is configured, the total number of sessions that were aged out at random because the number of free sessions dropped below the random threshold, in addition to the number of sessions that were aged out randomly in the last 60 seconds.Refer to “Configuring fast session aging” on page 298 for more information on the fast-age and random thresholds.

Statistics for Individual Real Servers

Server State The possible values for the server state. The state of each real server is shown by the State field.

Real Server The name of the real server. This is the name you gave the server when you configured it.

St The state of the real server. The state can be one of the states listed by "Server State" at the top of the display.

NOTE: The value in this field is based on the results of Layer 3 health checks. To display the server state based on Layer 4 or Layer 7 health checks, refer to the State field displayed by the show server real command. (Refer to “Displaying real server information and statistics” on page 508.)


TotConn The number of client connections on the server since the ServerIron ADX was last booted or restarted. A connection consists of two sessions, the client-to-server session and the server-to-client session.

Tot RevConn The total number of connections initiated by the server to a client.

CurrSess The number of sessions currently open on the ServerIron ADX.

PeakConn The highest number of simultaneous connections the ServerIron ADX has managed since it was last booted or restarted.

TABLE 55 Field descriptions for the show server session command (Continued)

Field Description


Displaying packet traffic statisticsC

Displaying packet traffic statisticsIn theory, each BP sends its counters to the MP. The MP then aggregates all the counters from each BP and synthesizes them into tables. However in reality, not all the BP counters are currently implemented on the MP.

The MP correctly shows most of the commonly used counters. For some counters, including the show server traffic and show server debug commands, you should use the rconsole command in the BPs and issue show commands from there.

Use the clear server traffic command to clear traffic statistics for real and virtual servers.

Syntax: show server traffic

SLB-chassis#rconsole 1 1SLB-chassis1/1#show server trafficClient->Server = 0 Server->Client = 0Drops = 0 Aged = 0Fw_drops = 0 Rev_drops = 0FIN_or_RST = 0 old-conn = 0Disable_drop = 0 Exceed_drop = 0Stale_drop = 0 Unsuccessful = 0SYN def/proxy RST = 0 Server Resets = 0Out of Memory = 0 Out of Memory = 0last conn rate = 0 max conn rate = 0last TCP attack rate = 0 max TCP attack rate = 0fast vport found = 0 fast vport n found = 0Fwd to non-static FI = 0 Dup stale SYN = 0

TCP forward FIN = 0 TCP reverse FIN = 0Fast path FWD FIN = 0 Fast path REV FIN = 0Fast path SLB SYN = 0 Dup SYN after FIN = 0Duplicate SYN = 0 Duplicate sessions = 0TCP ttl FIN recvd = 0 TCP ttl reset recvd = 0Sessions in DEL_Q = 0 Sess force deleted = 0Fwd sess not found = 0 sess already in delQ = 0Sess rmvd from delQ = 0Fragment buf full er = 0 Incoming TCP cksum e = 0New sess sync sent = 0 New sess sync recvd = 0L4 msg sent = 0 L4 msg recvd = 0brocade packet sent = 0 ipc packet sent = 8TCP SYN received = 0 TCP SYN dropped = 0TCP SYN to MP = 0 TCP SYN ACK to MP = 0TCP SYN ACK received = 0 TCP SYN ACK dropped = 0TCP pkt received = 0 TCP pkt dropped = 0TCP pkt to MP = 0 PBSLB tftp status = In progres


Displaying packet traffic statistics C

Table 56 lists the displayed information for bound ports.

TABLE 56 Field descriptions for the show server traffic command

Field Description

Client->Server Number of packets sent from clients to servers.

Server->Client Number of packets sent from servers to clients.

Drops Number of packets dropped by the ServerIron ADX. This statistic includes the following:• TCP Resets – Resets sent by the ServerIron ADX• Forward Resets – Resets from the client• Unsuccessful requests – Requests sent to a TCP or UDP port that is

not bound to the request’s destination VIP

Aged Number of TCP and UDP sessions that the ServerIron ADX closed because they aged out. A session ages out when the age timer configured on the ServerIron ADX expires. For more information, refer to “Configuring TCP age” on page 301 and “Configuring UDP age” on page 301.

Fw_drops Number of client-to-server packets the ServerIron ADX has dropped. If this statistic is high, there might not be a session entry. This scenario can occur under the following circumstances:• If the session is terminated normally but the client sends another

RESET.• If Denial of Service (DoS) protection is configured and has been

activated. • If the maximum number of sessions has been reached.• If all the real servers are down.

Rev_drops Number of server-to-client packets the ServerIron ADX has dropped. If this statistic is high, there might not be a session entry. This can occur for the same reasons as listed for the Fw_drops field.

FIN_or_RST Number of FINs or RSTs passing through (forward and reverse) a non-optimized path (no FPGA processing) inside the ServerIron ADX. All traffic is optimized (FPGA processed) by default except FTP control, streaming protocol control, and DNS traffic.

old-conn

fast vport found Number of successful virtual-port searches using an improved (faster) method.

Duplicate SYN When the ServerIron ADX receives a SYN packet for a session that is already listed in the session table (show server sessions), the ServerIron ADX has received a Duplicate SYN. The counter is then incremented by 1.

TCP ttl reset recvd Total (ttl) number of resets received in both the forward and reverse direction. This counter applies to both optimized (FPGA assisted) and non optimized traffic paths.

Disable_drop Number of packets the ServerIron ADX dropped because they were sent by a client to a VIP port that is bound to a real server port that is currently disabled.


Displaying configuration informationC

Displaying configuration informationThis section contains the following sections:

• “Showing aggregate health of tracked ports” on page 525

• “Auto repeat of show command output” on page 526

• “Clearing all session table entries” on page 526

• “Simplified Clearing of Server Sessions” on page 528

• “Clearing the connections counter” on page 528

Exceed_drop Number of packets dropped by the ServerIron ADX because the TCP SYN limit on the real servers had been reached. The TCP SYN limit is a configurable parameter that allows you to protect servers against TCP SYN attacks by limiting the number of TCP SYN requests the ServerIron ADX can send to the server each second. For more information, refer to “Configuring the maximum number of active sessions” on page 298.

Stale_drop Number of TCP SYN packets the ServerIron ADX dropped because they matched a stale session entry.

Unsuccessful Number of packets that were dropped for one of the following reasons:• A deny filter configured on the ServerIron ADX matched the packet,

causing the ServerIron ADX to drop the packet. • A client requested a TCP/UDP port that is not bound on the VIP.

last conn rate Rate of TCP traffic per second. This counter includes all TCP traffic, including TCP SYN DoS attacks. This field displays in releases 09.0.00S and later.

max conn rate Peak rate of TCP traffic (per second) encountered on this device. This field displays in releases 09.0.00S and later.

last TCP attack rate Rate of TCP Dos attacks per second. This rate is delayed by 1 to 2 minutes. This field displays in releases 09.0.00S and later.

max TCP attack rate Peak rate of TCP DoS attacks (per second) encountered on this device. This rate is delayed by 1 to 2 minutes. This field displays in releases 09.0.00S and later.

TABLE 56 Field descriptions for the show server traffic command (Continued)

Field Description


Displaying configuration information C

Showing aggregate health of tracked portsIf a real server port goes down, none of the track port groups on the real server are considered for load balancing. To check the health of track-group state, use the following command.

ServerIronADX(config)#show track-group-state

This command displays the state of all configured track groups on the ServerIron ADX, as shown in the following example.

NOTEThe state can be either UP or SUSPECT, depending on the state of the real server ports that are bound to track-group ports. The track-group state is never in a DOWN state.

The previous output displayed by the show track-group-state command is based upon the following configuration.

server real r1 10.10.1.101 port http port http url "HEAD /" port ftp port 3030!server real r2 10.10.1.102 port http port http url "HEAD /" port ssl!server real r3 10.10.1.103 port ssl port http port http url "HEAD /"!server virtual-name-or-ip v1 10.10.1.151 port http sticky port ftp sticky port 30303 sticky port 3030 sticky track-group http 21 bind http r1 http bind ftp r1 ftp bind 3030 r1 3030!server virtual-name-or-ip v2 10.10.1.153 port ssl sticky port http sticky track-group ssl 80 bind ssl r2 ssl bind http r2 http!server virtual-name-or-ip v3 10.10.1.154

ServerIronADX#show track-group-state Virtual Server track-group state

v1 80 3030 21 SUSPECT v2 443 80 UP v3 80 443 SUSPECT



port ssl sticky port http sticky track-group http 443 bind ssl r3 ssl bind http r3 http!

Auto repeat of show command output The repeat-show “cmd-to -how” interval command is a regular show command that is repeated at periodic intervals. You can issue this command from any mode (user, privileged, or configuration) from a Telnet session, SSH session, or a console.

To repeat the show command display at specific intervals, use the following command (on MP only).

ServerIronADX#repeat-show “show server session” 8

This example displays the results of a show server session command every 8 seconds.

Syntax: repeat-show cmd-to-show interval

The “cmd-to-show” variable is the actual command display to be shown repeatedly. The double quotes allow the command to accommodate white spaces.

The interval variable specifies the interval for repeated displays (range from 1 to 60 seconds).

To stop the repeat-show command in the current session, use the following command (on MP only).

ServerIronADX#stop-repeat-show

Syntax: stop-repeat-show

NOTEThe stop-repeat-show command stops all the repeat-show commands issued in the session.

The repeat-show commands are very similar to the traceroute and stop-traceroute commands. When you end a Telnet session, this command cleans up the Telnet session and issues the stop-repeat-show command.

Clearing all session table entries To clear all session table entries for a deleted real server, enter the clear server session command.

Syntax: clear server session name [name [name [name]]]

The name variable specifies the name of the real server. You can enter up to four real server names. It can take up to three minutes for the command to take effect. This command is supported only on the MP (the main processor management session).

When you delete a real server, the ServerIron ADX attempts to clear all the session entries for that real server from the session table. The ServerIron ADX requires all the sessions to be cleared from the table before performing these operations. If you use the force shutdown option (server force-delete command), the ServerIron ADX ends the sessions within one minute. Otherwise, the ServerIron ADX allows active sessions to end normally before removing them.


Displaying configuration information C

When you enter the command to delete a real server (no server real name command), the ServerIron ADX changes the server’s state to "await_delete". The real server remains in this state until all its sessions are cleared from the session table. Occasionally, the ServerIron ADX cannot clear all of a deleted real server’s sessions from the table. When this occurs, to safely delete the real server from the ServerIron, Brocade recommends the following procedure.

1. Under the real server, disable the application ports.

2. Check to confirm that the current connections in the session come down to zero (in the show server real command output).

3. Under VIP, unbind the real server.

4. Delete the real server.

To complete deletion of the server in this case, enter the clear server session name command after entering the no server real name command.

Example

The no server real command deletes real server "rs1". The show server real command displays the states of the real servers. Notice that rs1 is still listed as a valid real server, and has the state "await_delete". If the no server real command does not list the deleted server, the server has been completely deleted.

If the server continues to be listed with the "await_delete" state after several minutes, enter the clear server session command to finish deleting the server. The clear server session command deletes the remaining sessions for rs1, after which the ServerIron ADX can finish deleting the server. You can enter this command immediately after entering the no server real command. You do not need to wait for any sessions to end normally.

NOTEThe clear server session real server command is used to clear sessions for a specific real server, regardless of the server in "await_del" or "await_u" state.

The clear server all-session real-server command is an enhancement to the clear server session command. If the command is executed from MP, it clears all the session in MP and BP and it clears only the BP sessions if it is executed from BP.

The real server variable in the clear server all-session command is an optional.

ServerIronADX(config)#no server real rs1ServerIronADX(config)#show server real rs1Real Servers InfoName : rs1 Mac-addr: UnknownIP:10.2.3.4 Range:1 State:await_delete Max-conn:1000000Least-con Wt:0 Resp-time Wt:0

Port State Ms CurConn TotConn Rx-pkts Tx-pkts Rx-octet Tx-octet Reas---- ----- -- ------- ------- ------- ------- -------- -------- ----8080 unbnd 0 0 0 0 0 0 0 0default unbnd 0 0 0 0 0 0 0 0

Server Total 0 0 0 0 0 0 0 ServerIronADX(config)#clear server session rs1



Simplified Clearing of Server SessionsThe clear server command is enhanced with additional options to simplify clearing of server-bound sessions.

Clearing sessions for real servers and real server port

To clear sessions of a real server or a port under real server, use the following command:

ServerIronADX# clear server all-session real-server rs1ServerIronADX# clear server all-session real-server rs1 port 80

Syntax: clear server all-session [ real-server real-server-name ] [ port port-number ]

The real-server real-server-name parameters are optional. The real server name variable identifies the name of a real server whose sessions are to be deleted.

The port port-number parameters are optional. The port number variable identifies real-server port whose sessions needs to be deleted.

Clearing sessions for virtual servers and virtual server port

The multi-port binding feature allows for binding of same real server port from multiple virtual servers. In such cases, it isn't possible to clear sessions that pertain to only one of the virtual servers. The 'clear server' command is enhanced to include virtual server name and address this challenge.

To clear sessions of a virtual server or a port under virtual server, use following command:

ServerIronADX# clear server all-session virtual-server vs1ServerIronADX# clear server all-session virtual-server vs1 port 80

Syntax: clear server all-session [ virtual-server virtual-server-name ] [port port-number]

The virtual-server virtual-server-name parameters are optional. The virtual-server name variable identifies the name of a virtual server whose sessions are to be deleted.

The port port-number parameters are optional. The port number variable identifies virtual-server port whose sessions needs to be deleted.

Clearing the connections counterYou can clear the counter for real servers only or virtual servers only.

To clear the total connections counter (“Tot-Conn”) in show commands for real and virtual servers, enter a command such as the following.

ServerIronADX(config-vs-Brocade)#clear server tot-conn virtual

Syntax: clear server tot-conn real | virtual



Appendix

D
SLB Configuration Examples
Web hosting with multiple virtual servers mapped to one real server

Suppose an ISP administrator wants to use one real server to accommodate three premium users, all of which are Web sites. Each of these premium users is assigned its own website URL:

• www.fox.com

• www.horse.com

• www.tiger.com

As shown in Figure 60, the SLB switch forwards requests received for each of the three websites to the real servers assigned to handle the traffic.

529

Multiple port binding using port aliasesD

FIGURE 60 One real server hosting multiple virtual servers

Multiple port binding using port aliasesMost SLB configurations for Web hosting map one virtual IP address to multiple real servers. However, suppose an ISP wants to host one or multiple domain names on the same real server, using the same TCP/UDP port and use a different VIP for each site. Using a separate VIP for each Web site eases administration and accounting by allowing the ISP to display statistics on the ServerIron ADX for each VIP address. In addition, you can create the appearance that you have many Web servers even if you have only a few.

If you want to bind multiple VIPs to the same TCP/UDP port on the same real server for accounting reasons, one method for doing so is to create an alias for each virtual port; alternatively, you can use multiple port binding to directly bind a real server port to multiple VIPs.

• When you create an alias, you configure the VIP to bind to a different port number on the real server, then disable port translation for that binding. The ServerIron ADX collects and presents information for the alias port number, but traffic from all the VIPs goes to the same TCP/UDP port number on the real server.

• Multiple port binding enables you to eliminate the time and effort required to configure aliases for multiple VIPs.


TCP/UDP application groups D

To map multiple virtual IP addresses to the same real server, disable HTTP port translation for all but one of the virtual IP addresses, then bind the virtual IP addresses to an alias HTTP port. Disabling HTTP port translation enables the virtual IP addresses to use the same actual HTTP port number on the real server while the ServerIron ADX collects and displays separate statistics for the alias HTTP port number associated with each virtual IP address.

Figure 61 shows an example of this type of configuration.

FIGURE 61 Multiple virtual IP addresses mapped to the same real server

TCP/UDP application groupsNormally, when the ServerIron ADX selects a real server for a client’s request for a TCP/UDP port, there is no guarantee that the ServerIron ADX will select the same real server for subsequent requests from the same client. In many situations, this does not present a problem. Even when the client is requesting the same Web page or application, if the content or service is replicated on all the real servers, the client does not know or care which real server provides the content or service for each request.

However, some applications may require that the client continue to use the same real server. For example, an interactive Web site might require successive client requests to come to the same server. Other applications might require that additional TCP/UDP applications also be on the same real server. Some applications may even require the ability to open concurrent connections on the client with different TCP/UDP ports dynamically assigned by the real server.

In all of these cases, the predictor (load-balancing metric) does not ensure that the client returns to the same real server. To accommodate these types of applications, you can configure ports on a virtual server to have the following attributes:

TABLE 57 Virtual IP addresses mapped to the same real server

Virtual domain Name Virtual IP TCP Port Real IP TCP Port

www.travel.com 10.157.22.88 80 S1: 10.0.1.5S2: 10.0.2.200

80

www.weather.com 10.157.22.99 80 S1: 10.0.1.5S2: 10.0.2.200

180


TCP/UDP application groupsD

• Sticky connections – When you add a TCP/UDP port to a virtual server, if you specify that the port is “sticky”, a client request for that port always goes to the same real server unless the sticky age timer has expired. The sticky age timer ages out inactive sticky server connections. Possible values are from 2 through 60 minutes. The default is 5 minutes. For more information, see “Setting the sticky age” on page 66.

• TCP/UDP application groups (using the track port function) – A “primary” TCP/UDP port is grouped with up to four additional TCP/UDP ports. After the ServerIron ADX sends a client request for the primary port to a real server, subsequent requests from the client for ports grouped with the primary port go to the same real server. For more information, see “Tracking primary ports” on page 73.

• TCP/UDP application groups (using the track group function) – Up to eight TCP/UDP ports are grouped together. After the ServerIron ADX sends a client request for any of the grouped ports to a real server, subsequent requests from the client for ports in the group go to the same real server. For more information, see “Track port group function” on page 74.

NOTEYou must configure all the ports in a TCP/UDP application group to be “sticky”.

• Concurrent connections – The real server can open additional ("concurrent") TCP/UDP sessions with the client using arbitrary TCP/UDP port numbers.

NOTEAlthough the concurrent connections attribute is similar to application groups, application groups apply to specific TCP/UDP ports that you configure on the virtual server. Concurrent connections enable the real server to arbitrarily determine the TCP/UDP ports and assign them to the client.

NOTEFor servers that use passive FTP *in DSR configuration*, configure the FTP ports to be both sticky and concurrent.

Figure 62 shows an example of servers configured with sticky ports and an application group. In this example, the content on each real server is identical. However, some applications on the server require that clients use the same server for subsequent requests to the application. The virtual server is configured to make the ports sticky and to group the TFTP and Telnet ports under the HTTP port.

FIGURE 62 Sticky ports and application group (using the track-port function) used to group TCP/UDP applications


TCP/UDP application groups D

To implement an application group for this example, enter the following commands.

ServerIronADX(config)#server real-name r1 10.0.1.5 ServerIronADX(config-rs-r1)#port httpServerIronADX(config-rs-r1)#port tftpServerIronADX(config-rs-r1)#port telnetServerIronADX(config-rs-r1)#exitServerIronADX(config)#server real-name r2 10.0.2.200 ServerIronADX(config-rs-r2)#port httpServerIronADX(config-rs-r2)#port tftpServerIronADX(config-rs-r2)#port telnetServerIronADX(config-rs-r2)#exit

After you enter information for the real servers, you are ready to create the virtual server. To create the virtual server, enter the following commands.

ServerIronADX(config)#server virtual-name-or-ip v1 10.157.22.1ServerIronADX(config-vs-v1)#port 80 stickyServerIronADX(config-vs-v1)#port 69 stickyServerIronADX(config-vs-v1)#port 23 stickyServerIronADX(config-vs-v1)#track 80 69 23ServerIronADX(config-vs-v1)#bind 80 r1 80 r2 80ServerIronADX(config-vs-v1)#bind 23 r1 23 r2 23ServerIronADX(config-vs-v1)#bind 69 r1 69 r2 69ServerIronADX(config-vs-v1)#exit

The commands above illustrate the track port function. The sticky parameter makes the TCP/UDP ports sticky. The track command groups the Telnet port (23) and the TFTP port (69) under the HTTP port (80); the HTTP port is established as the “primary” port. After the ServerIron ADX sends a client to a real server for the HTTP port, subsequent requests from that client for the HTTP, TFTP, or Telnet port go to the same real server. Up to four ports can be grouped with the primary port.

NOTEBecause ports 23 and 69 track port 80, state information for the tracking ports (23 and 69 in this example) are based on the tracked port’s state (port 80 in this example). The state is shown in the Ms (Master port state) field of the display produced by the show server real command. Refer to “Displaying real server information and statistics” on page 508.

The track group function works similarly to the track port function. With the track port function, the client uses the same server for applications associated with the grouped ports, as long as the primary port is active. In contrast, with the track group function, the client uses the same server for applications associated with the grouped ports, as long as all the ports in the group are active. After the ServerIron ADX sends a client to a real server for any of the grouped ports, subsequent requests from that client for any of the grouped ports go to the same real server.

The following commands illustrate the track group function.

ServerIronADX(config)#server virtual-name-or-ip v1 10.157.22.1ServerIronADX(config-vs-v1)#port 80 stickyServerIronADX(config-vs-v1)#port 69 stickyServerIronADX(config-vs-v1)#port 23 stickyServerIronADX(config-vs-v1)#track-group 80 69 23ServerIronADX(config-vs-v1)#bind 80 r1 80 r2 80ServerIronADX(config-vs-v1)#bind 23 r1 23 r2 23ServerIronADX(config-vs-v1)#bind 69 r1 69 r2 69ServerIronADX(config-vs-v1)#exit


Web hosting with ServerIron ADX and real servers in different subnetsD

In this example, the track-group command groups the HTTP port (80), Telnet port (23), and TFTP port (69) together. Whenever a client attempts to connect to a port within the group, the ServerIron ADX ensures all ports in the group are active before granting the connection.

The sticky parameter makes the TCP/UDP ports sticky. The sticky parameter must be set for all ports in the group.

After the ServerIron ADX sends a client to a real server for any of these three ports, subsequent requests from that client for the HTTP, TFTP, or Telnet port go to the same real server. Up to eight ports can be grouped together using the track group function. A port can be part of only one group. The track-group and track commands for a port are mutually exclusive.

Web hosting with ServerIron ADX and real servers in different subnets

The ServerIron ADX allows you to easily deploy its services in a multinetted environment, without the overhead of configuring routing protocols.

Normally, the ServerIron ADX requires only one IP address, which you use for management access to the device. However, when the ServerIron ADX and real servers are on different subnets, you need either a multiple subnets configured on the router, or source NAT-enabled and source IP addresses (up to eight) configured on the ServerIron ADX.

Figure 63 shows an example of a multinetted environment, in which the ServerIron ADX is on one sub-net, but the real servers are on another subnet. The ServerIron ADX is on subnet 10.149.65.x, and the real servers are on subnet 10.10.10.x.

FIGURE 63 ServerIron ADX and real servers in multinetted environment – router configured to route between subnet

In this example, the ServerIron ADX and the real servers are on different subnets but can still communicate, because the router is configured with interfaces in both subnets. Traffic from the ServerIron ADX to the real servers goes to the router, which routes the traffic to the real servers’ subnet. (The traffic passes back through the ServerIron ADX to reach the real servers, but still must be routed by the router.)

Traffic from the real servers to the ServerIron ADX passes through the ServerIron ADX to the router. The ServerIron ADX acts like a Layer 2 bridge in this case and passes the traffic to the router. The router then routes the traffic to the ServerIron ADX’s sub-net.

If you have network topology similar to the example in Figure 63, but you do not want to configure the router with multiple subnets, you can instead enable source NAT and configure a source IP address on the ServerIron ADX. The source IP address allows the ServerIron ADX to be in multiple subnets, in addition to the sub-net of the ServerIron ADX’s management IP address. Source NAT


Web hosting with ServerIron ADX and real servers in different subnets D

enables the ServerIron ADX to perform IP address translation on the source address in packets addressed to the real servers. When source NAT is enabled, the ServerIron ADX changes the source address in the IP packets addressed to the real server and alters it to match the source IP address configured on the ServerIron ADX. Figure 64 shows an example of the topology shown in Figure 63, although in this case the ServerIron ADX is configured for multiple subnets instead of the router.

FIGURE 64 ServerIron ADX and real servers in multinetted environment – ServerIron ADX configured for source NAT

In this example, the ServerIron ADX is configured with source IP addresses in the real server’s subnet, and source NAT is enabled. The configuration requires five CLI commands. No reconfiguration of the router is required.

The ServerIron ADX supports a maximum of 64,000 simultaneous connections on each source IP address. This maximum value is based on the architectural limits of IP itself. As a result, if you add only one source IP address, the ServerIron ADX can support up to a maximum of 64,000 simultaneous connections to the real servers. You can configure up to eight source IP addresses, for even more simultaneous connections to the real servers.

To implement the configuration shown in Figure 64, enter commands such as the following.

ServerIronADX(config)#server source-ip 10.10.10.5 255.255.255.0 0.0.0.0ServerIronADX(config)#server source-ip 10.10.10.6 255.255.255.0 0.0.0.0ServerIronADX(config)#server source-ip 10.10.10.7 255.255.255.0 0.0.0.0ServerIronADX(config)#server source-ip 10.10.10.8 255.255.255.0 0.0.0.0ServerIronADX(config)#server source-natServerIronADX(config)#server real-name R1 10.10.10.2 ServerIronADX(config-rs-r1)#port httpServerIronADX(config-rs-r1)#exitServerIronADX(config)#server real-name R2 10.10.10.3 ServerIronADX(config-rs-r2)#port httpServerIronADX(config-rs-r2)#exitServerIronADX(config)#server virtual-name-or-ip VIP 10.157.22.88ServerIronADX(config-vs-VIP1)#port httpServerIronADX(config-vs-VIP1)#bind http R1 http R2 httpServerIronADX(config-vs-VIP1)#exit

NOTEIf a real server is not reachable from the ServerIron ADX at Layer 2 (does not respond to ARP requests), and if the router connecting the ServerIron ADX to the real server is not running proxy ARP, use the following command instead.

server remote-name name ip-addr

This command adds the server as a remote server. Alternatively, enable proxy ARP on the router connecting the ServerIron ADX to the real server.


SLB with ServerIron running Layer 3 imageD

SLB with ServerIron running Layer 3 imageThe following sections illustrate Layer 3 SLB support in these configurations:

• “Basic SLB with one VLAN and one virtual routing interface” on page 536

• “Basic SLB with multiple subnets and multiple virtual routing interfaces” on page 539

Basic SLB with one VLAN and one virtual routing interface

Figure 65 illustrates an SLB configuration with one VLAN and one virtual routing interface.

FIGURE 65 Basic SLB configuration with one VLAN and one virtual routing interface

The following commands configure a virtual routing interface on VLAN 1 (the default VLAN), then configure IP addresses on the virtual routing interface.

ServerIronADX(config)#vlan 1 name DEFAULT-VLAN by portServerIronADX(config-vlan-1)#router-interface ve 1ServerIronADX(config-vlan-1)#exitServerIronADX(config)#interface ve 1ServerIronADX(config-ve-1)#ip address 10.1.1.254 255.255.255.0ServerIronADX(config-ve-1)#ip address 10.128.1.254 255.255.255.0ServerIronADX(config-ve-1)#ip address 10.65.1.254 255.255.255.0ServerIronADX(config-ve-1)#ip ospf area 0ServerIronADX(config-ve-1)#exitServerIronADX(config)#ip l4-policy 1 cache tcp 0 globalServerIronADX(config)#ip l4-policy 2 cache udp 0 global


SLB with ServerIron running Layer 3 image D

The following list of commands configures OSPF and enables redistribution of static and connected routes into OSPF.

ServerIronADX(config)#router ospfServerIronADX(config-ospf-router)#area 0 ServerIronADX(config-ospf-router)#redistribution connected ServerIronADX(config-ospf-router)#redistribution static ServerIronADX(config-ospf-router)#exit

The following commands configure the real servers in Figure 65.

ServerIronADX(config)#server real rs23 10.1.1.23ServerIronADX(config-rs-rs23)#port dnsServerIronADX(config-rs-rs23)#port mmsServerIronADX(config-rs-rs23)#port ftpServerIronADX(config-rs-rs23)#port sslServerIronADX(config-rs-rs23)#port httpServerIronADX(config-rs-rs23)#port http url "HEAD /"ServerIronADX(config-rs-rs23)#exitServerIronADX(config)#server real rs24 10.1.1.24ServerIronADX(config-rs-rs24)#port dnsServerIronADX(config-rs-rs24)#port mmsServerIronADX(config-rs-rs24)#port ftpServerIronADX(config-rs-rs24)#port sslServerIronADX(config-rs-rs24)#port httpServerIronADX(config-rs-rs24)#port http url "HEAD /"ServerIronADX(config-rs-rs24)#exitServerIronADX(config)#server real rs25 10.1.1.25ServerIronADX(config-rs-rs25)#port dnsServerIronADX(config-rs-rs25)#port mmsServerIronADX(config-rs-rs25)#port ftpServerIronADX(config-rs-rs25)#port sslServerIronADX(config-rs-rs25)#port httpServerIronADX(config-rs-rs25)#port http url "HEAD /"ServerIronADX(config-rs-rs25)#exit


SLB with ServerIron running Layer 3 imageD

The following commands configure the remote servers in Figure 65.

ServerIronADX(config)#server remote-name rs26 10.2.24.26ServerIronADX(config-rs-rs26)#source-natServerIronADX(config-rs-rs26)#port dnsServerIronADX(config-rs-rs26)#port ftpServerIronADX(config-rs-rs26)#port sslServerIronADX(config-rs-rs26)#port httpServerIronADX(config-rs-rs26)#port http url "HEAD /"ServerIronADX(config-rs-rs26)#exitServerIronADX(config)#server remote-name rs27 10.2.24.27ServerIronADX(config-rs-rs27)#source-natServerIronADX(config-rs-rs27)#port dnsServerIronADX(config-rs-rs27)#port ftpServerIronADX(config-rs-rs27)#port sslServerIronADX(config-rs-rs27)#port httpServerIronADX(config-rs-rs27)#port http url "HEAD /"ServerIronADX(config-rs-rs27)#exit

The following commands configure the virtual servers in Figure 65.

ServerIronADX(config)#server virtual-name-or-ip www 10.65.1.100ServerIronADX(config-vs-www)#port ssl stickyServerIronADX(config-vs-www)#port httpServerIronADX(config-vs-www)#bind ssl rs25 ssl rs24 ssl rs23 sslServerIronADX(config-vs-www)#bind ssl rs27 ssl rs26 sslServerIronADX(config-vs-www)#bind http rs25 http rs24 http rs23 httpServerIronADX(config-vs-www) #bind http rs27 http rs26 httpServerIronADX(config-vs-www)#exitServerIronADX(config)#server virtual-name-or-ip ftp 10.65.1.101ServerIronADX(config-vs-ftp)#port ftpServerIronADX(config-vs-ftp)#bind ftp rs25 ftp rs24 ftp rs23 ftpServerIronADX(config-vs-ftp)#bind ftp rs27 ftp rs26 ftpServerIronADX(config-vs-ftp)#exitServerIronADX(config)#server virtual-name-or-ip mms 10.65.1.102ServerIronADX(config-vs-mms)#port mmsServerIronADX(config-vs-mms)#bind mms rs25 mms rs24 mms rs23 mmsServerIronADX(config-vs-mms)#exitServerIronADX(config)#server virtual-name-or-ip dns 10.65.1.103ServerIronADX(config-vs-dns)#port dnsServerIronADX(config-vs-dns)#bind dns rs25 dns rs24 dns rs23 dns


Basic SLB with multiple subnets and multiple virtual routing interfaces D

Basic SLB with multiple subnets and multiple virtual routing interfaces

Figure 66 illustrates an SLB configuration with three VLANs and three virtual routing interfaces.

FIGURE 66 Basic SLB configuration with three VLANs and three virtual routing interfaces

The following commands configure virtual routing interfaces on VLAN 1 (the default VLAN), VLAN 2, and VLAN 4 and configure IP addresses on the virtual routing interfaces.

ServerIronADX(config)#vlan 1 name DEFAULT-VLAN by portServerIronADX(config-vlan-1)#router-interface ve 1ServerIronADX(config-vlan-1)#exitServerIronADX(config)#interface ve 1ServerIronADX(config-ve-1)#ip address 10.65.1.254 255.255.255.0ServerIronADX(config-ve-1)#ip ospf area 0ServerIronADX(config-ve-1)#exitServerIronADX(config)#ip l4-policy 1 cache tcp 0 globalServerIronADX(config)#ip l4-policy 2 cache udp 0 globalServerIronADX(config)#vlan 2 by portServerIronADX(config-vlan-2)#untagged ethe 3/7 to 3/12 ethe 4/3 to 4/4 ServerIronADX(config-vlan-2)#router-interface ve 2ServerIronADX(config-vlan-2)#exitServerIronADX(config)#interface ve 2ServerIronADX(config-ve-2)#ip address 10.1.1.254 255.255.255.0ServerIronADX(config-ve-2)#ip ospf area 0ServerIronADX(config-ve-2)#exit


Basic SLB with multiple subnets and multiple virtual routing interfacesD

ServerIronADX(config)#vlan 4 by portServerIronADX(config-vlan-4)#untagged ethe 3/13 to 3/24 ethe 4/5 to 4/8 ServerIronADX(config-vlan-4)#ip-subnet 10.128.1.0 255.255.255.0 name PrivateNetServerIronADX(config-vlan-4)#static ethe 3/13 to 3/24 ethe 4/5 to 4/8 ServerIronADX(config-vlan-4)#router-interface ve 4ServerIronADX(config-vlan-4)#exitServerIronADX(config)#interface ve 4ServerIronADX(config-ve-4)#ip address 10.128.1.254 255.255.255.0ServerIronADX(config-ve-4)#ip ospf area 0ServerIronADX(config-ve-4)#exit

The following list of commands configures OSPF and enables redistribution of static as well as connected routes into OSPF.

ServerIronADX(config)#router ospfServerIronADX(config-ospf-router)#area 0 ServerIronADX(config-ospf-router)#redistribution connected ServerIronADX(config-ospf-router)#redistribution static ServerIronADX(config-ospf-router)#exit

The following commands configure the real servers in Figure 66.

ServerIronADX(config)#server real rs23 10.1.1.23ServerIronADX(config-rs-rs23)#port dnsServerIronADX(config-rs-rs23)#port mmsServerIronADX(config-rs-rs23)#port ftpServerIronADX(config-rs-rs23)#port sslServerIronADX(config-rs-rs23)#port httpServerIronADX(config-rs-rs23)#port http url "HEAD /"ServerIronADX(config-rs-rs23)#exitServerIronADX(config)#server real rs24 10.1.1.24ServerIronADX(config-rs-rs24)#port dnsServerIronADX(config-rs-rs24)#port mmsServerIronADX(config-rs-rs24)#port ftpServerIronADX(config-rs-rs24)#port sslServerIronADX(config-rs-rs24)#port httpServerIronADX(config-rs-rs24)#port http url "HEAD /"ServerIronADX(config-rs-rs24)#exitServerIronADX(config)#server real rs25 10.1.1.25ServerIronADX(config-rs-rs25)#port dnsServerIronADX(config-rs-rs25)#port mmsServerIronADX(config-rs-rs25)#port ftpServerIronADX(config-rs-rs25)#port sslServerIronADX(config-rs-rs25)#port httpServerIronADX(config-rs-rs25)#port http url "HEAD /"ServerIronADX(config-rs-rs25)#exit

The following commands configure the remote servers in Figure 66.

ServerIronADX(config)#server remote-name rs26 10.2.24.26ServerIronADX(config-rs-rs26)#source-natServerIronADX(config-rs-rs26)#port dnsServerIronADX(config-rs-rs26)#port ftpServerIronADX(config-rs-rs26)#port sslServerIronADX(config-rs-rs26)#port httpServerIronADX(config-rs-rs26)#port http url "HEAD /"ServerIronADX(config-rs-rs26)#exitServerIronADX(config)#server remote-name rs27 10.2.24.27ServerIronADX(config-rs-rs27)#source-natServerIronADX(config-rs-rs27)#port dnsServerIronADX(config-rs-rs27)#port ftp


Basic SLB with multiple subnets and multiple virtual routing interfaces D

ServerIronADX(config-rs-rs27)#port sslServerIronADX(config-rs-rs27)#port httpServerIronADX(config-rs-rs27)#port http url "HEAD /"ServerIronADX(config-rs-rs27)#exit

The following commands configure the virtual servers in Figure 66.

ServerIronADX(config)#server virtual-name-or-ip www 10.65.1.100ServerIronADX(config-vs-www)#port ssl stickyServerIronADX(config-vs-www)#port httpServerIronADX(config-vs-www)#bind ssl rs25 ssl rs24 ssl rs23 sslServerIronADX(config-vs-www)#bind ssl rs27 ssl rs26 sslServerIronADX(config-vs-www)#bind http rs25 http rs24 http rs23 httpServerIronADX(config-vs-www)#bind http rs27 http rs26 httpServerIronADX(config-vs-www)#exitServerIronADX(config)#server virtual-name-or-ip ftp 10.65.1.101ServerIronADX(config-vs-ftp)#port ftpServerIronADX(config-vs-ftp)#bind ftp rs25 ftp rs24 ftp rs23 ftpServerIronADX(config-vs-ftp)#bind ftp rs27 ftp rs26 ftpServerIronADX(config-vs-ftp)#exitServerIronADX(config)#server virtual-name-or-ip mms 10.65.1.102ServerIronADX(config-vs-mms)#port mmsServerIronADX(config-vs-mms)#bind mms rs25 mms rs24 mms rs23 mmsServerIronADX(config-vs-mms)#exitServerIronADX(config)#server virtual-name-or-ip dns 10.65.1.103ServerIronADX(config-vs-dns)#port dnsServerIronADX(config-vs-dns)#bind dns rs25 dns rs24 dns rs23 dns


Basic SLB with multiple subnets and multiple virtual routing interfacesD



Appendix

E
Acknowledgements
This appendix presents the acknowledgements for portions of code from various vendors that are included in the Brocade devices covered in this manual.

OpenSSL licenseCopyright (c) 1998-2001 The OpenSSL Project. All rights reserved.

1. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

2. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

3. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation or other materials provided with the distribution.

4. All advertising materials mentioning features or use of this software must display the following acknowledgment: “This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit. (http://www.openssl.org/)”

5. The names “OpenSSL Toolkit” and “OpenSSL Project” must not be used to endorse or promote products derived from this software without prior written permission. For written permission, please contact [email protected].

6. Products derived from this software may not be called “OpenSSL” nor may “OpenSSL” appear in their names without prior written permission of the OpenSSL Project.

7. Redistributions of any form whatsoever must retain the following acknowledgment: “This product includes software developed by the OpenSSL Project for use in the OpenSSL Toolkit (http://www.openssl.org/)”

THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT “AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

543

mailto: [email protected]

http://www.openssl.org/

http://www.openssl.org/

Cryptographic softwareE

Cryptographic softwareThis product includes cryptographic software written by Eric Young ([email protected]). This product includes software written by Tim Hudson ([email protected]).

Original SSLeay LicenseCopyright (C) 1995-1998 Eric Young ([email protected])/. All rights reserved.

This package is an SSL implementation written by Eric Young ([email protected]). The implementation was written so as to conform with Netscape’s SSL.

This library is free for commercial and non-commercial use as long as the following conditions are adhered to. The following conditions apply to all code found in this distribution, be it the RC4, RSA, lhash, DES, etc., code; not just the SSL code. The SSL documentation included with this distribution is covered by the same copyright terms except that the holder is Tim Hudson ([email protected]).

Copyright remains Eric Young's, and as such any Copyright notices in the code are not to be removed. If this package is used in a product, Eric Young should be given attribution as the author of the parts of the library used. This can be in the form of a textual message at program startup or in documentation (online or textual) provided with the package.

1. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

2. Redistributions of source code must retain the copyright notice, this list of conditions and the following disclaimer.

3. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation or other materials provided with the distribution.

4. All advertising materials mentioning features or use of this software must display the following acknowledgement:

“This product includes cryptographic software written by Eric Young ([email protected])” The word 'cryptographic' can be left out if the routines from the library being used are not cryptographic related:-).

5. If you include any Windows specific code (or a derivative thereof) from the apps directory (application code) you must include an acknowledgement:

“This product includes software written by Tim Hudson ([email protected])”

THIS SOFTWARE IS PROVIDED BY ERIC YOUNG “AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.









Original SSLeay License E

The license and distribution terms for any publicly available version or derivative of this code cannot be changed. i.e. this code cannot simply be copied and put under another distribution license [including the GNU Public License.]


Original SSLeay LicenseE


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