1F0_4553_c1 © 1999, Cisco Systems, Inc. Cisco Load Balancing Solutions.

1F0_4553_c1 © 1999, Cisco Systems, Inc.

Cisco Load Balancing Cisco Load Balancing SolutionsSolutions


AgendaAgenda

• Problems We Are Solving

• DistributedDirector

• LocalDirector

• MultiNode Load Balancing


Problems We Are SolvingProblems We Are Solving

• Efficient, high-performance clientaccess to large server complexes

• Continuous availability of server applications

• Scalable, intelligent load distribution across servers in the complex

• Load distribution based on servercapacity of doing work and application availability

4F0_4553_c1 © 1999, Cisco Systems, Inc. 4

DistributedDirectorDistributedDirector

F0_4553_c1 © 1999, Cisco Systems, Inc.


What Is DistributedDirector?What Is DistributedDirector?

• Two pieces:

Standalone software/hardware bundleSpecial Cisco IOS®-based software on

Cisco 2501, 2502, and Cisco 4700M hardware platforms—11.1IA release train

Cisco IOS software release 11.3(2)T andlater on DRP-associated routers in field

• DistributedDirector is NOT a router

• Dedicated box for DistributedDirector processing


What Does What Does DistributedDirector Do?DistributedDirector Do?

• Resolves domain or host names to aspecific server (IP address)

• Provides transparent access to topologicallyclosest Internet/intranet server relative to client

• Maps a single DNS host name to the “closest”server to client

• Dynamically binds one of several IP addressesto a single host name

• Eliminates need for end-users to choose froma list of URL/host names to find “best” server

• The only solution which uses intelligence in the network infrastructure to direct client to best server


APPL2

APPL1

APPL3

2.2.2.1

IP

DD

Client

12

34

1.1.1.1

3.3.3.1

Resolve appl.com

DNS-Based DistributionDNS-Based Distribution

• Client connects to appl.com

• appl.com request routedto DistributedDirector

• DistributedDirectoruses multipledecision metrics toselect appropriateserver destination

• DistributedDirector sends destination address to client

• Client connects to the appropriate server


How Are DistributedDirector How Are DistributedDirector Choices Made?Choices Made?

• Director Response Protocol (DRP)Interoperates with remote routers (DRP agents)to determine network topology

Determines network distance between clients and server

• Client-to-server link latency (RTT)

• Server availability

• Administrative “cost”Take a server out of service for maintenance

• Proportional distributionFor heterogeneous distributed server environments

• Random distribution


Client

WebServer DistributedDirector

DRP Agents

Internet

Web Server

Director Response Protocol (DRP)Director Response Protocol (DRP)

• Operates with routers in thefield to determine:

Client-to-server network proximity

Client-to-serverlink latency


Client

AS3

AS1

AS4

One Hop

Two Hops

AS2

Server

DRP

Server

DRP

DRP “External” MetricDRP “External” Metric

• Measures distance from DRP agents to client in BGP AS hop counts

Server

DRP


• Measures client-to-DRPserver round-trip times

• Compares link latencies

• Server with lowest round-triptime is considered “best”

• Maximizes end-to-endserver accessperformance

DRP “Round-Trip Time” MetricDRP “Round-Trip Time” Metric

RTT Measurement

Client

AS1

AS4

Server

DRP

Server

DRP

AS3

AS2

Server

DRP


““Portion” MetricPortion” Metric

• Proportional load distribution across heterogeneous servers

• Can also be used to enable traditional round-robin DNS

Server 1 SPARCstationServer 1 SPARCstation

Server 2SPARCstationServer 2SPARCstation

Server 3Pentium 60 MHzServer 3Pentium 60 MHz


“Portion”Metric Value

“Portion”Metric Value


7/24 = 29.2%7/24 = 29.2%

8/24 = 33.3%8/24 = 33.3%

2/24 = 8.3%2/24 = 8.3%

2/24 = 8.3%2/24 = 8.3%

5/24 = 20.8%5/24 = 20.8%

24/24 = 100%24/24 = 100%

Portion ofConnections

Portion ofConnections

77

88

22

22

55

Total = 24Total = 24


Server Availability ParameterServer Availability Parameter

• DistributedDirector establishes a TCP connection to the service port on each remote server, thus verifying that the service is available

• Verification is made at regular intervals

• Port number and connection interval are configurable

• Minimum configurable interval is ten seconds

• Maximizes service availability as seen by clients


DistributedDirector—DistributedDirector—How Does It Work?How Does It Work?

• Two configuration modes:

DNS caching name server authoritative for www.foo.com subdomain

HTTP redirector for http://www.foo.com

• Modes configurable onper-domain basis


DistributedDirector—RedundancyDistributedDirector—Redundancy

•DNS mode

Use multiple DistributedDirectorsto provide several name servers authoritative for agiven hostname to provide redundancy

All DistributedDirectors are considered to be primary DNS servers

•HTTP mode

Use multiple DistributedDirectors and Cisco’s Hot Standby Router Protocol (HSRP)to provide redundancy


LocalDirectorLocalDirector



LocalDirectorLocalDirector

• LocalDirector appliance front-ends server farmLoad balances connections to “best server”

Failures, changes transparent to end users

Improves response time

Simplifies operations and maintenance

• Simultaneously supports different serverplatforms, operating systems

• Any TCP service (not just Web)

LocalDirector

Data Center

Internet or Intranet

User


LocalDirector—LocalDirector—Server ManagementServer Management

• Represents multiple servers with a single virtual address

• Easily place servers in and out of service

• Identifies failed servers: takes offline

• Identifies working servers: places in service

• IP address management

• Application-specific servers

• Maximum connections

• Hot-standby server


LocalDirector—SpecificationsLocalDirector—Specifications

• 80-Mbps throughput—model 416

• 300-Mbps throughput—model 430 Fast Ethernet channel

• Supports up to 64,000 virtual and real IP addresses

• Up to 16 10/100 Ethernet, 4 FDDI ports

• One-million simultaneous TCP connections

• TCP, UDP applications supported


Network Address TranslationNetwork Address Translation

• Client traffic destined forvirtual address is distributedacross multiple real addressesin the server cluster

• Transparent to client and server

• Network AddressTranslation (NAT)

Requires all traffic topass through LocalDirector

• Virtuals and reals areIP address/port combination Client

Client

Client

IP

Server 2Server 1 Server 3

LocalDirector 1.1.1.1

3.3.3.12.2.2.22.2.2.1

VirtualAddress

RealAddresses

Server Cluster


Session Distribution AlgorithmSession Distribution Algorithm

• Passive approach

Least connections

Weighted

Fastest

Linear

Source IP


Ideal for Mission-Critical Ideal for Mission-Critical ApplicationsApplications

TAP ServersMail, Web, FTP, and so on

LocalDirector

High-Availability Solution


LocalDirector StrengthsLocalDirector Strengths

• Network Address Translation (NAT)allows arbitrary IP topology between LocalDirector and servers

• Proven market leader with extensivefield experience

• Rich set of features to map betweenvirtual and real addresses

• Bridge-like operation allows transparent deployment and gradual migration to NAT


LocalDirector WeaknessesLocalDirector Weaknesses

• NAT requires all traffic to be routed through a single box

• NAT requires that data be scanned and manipulated beyond the TCP/UDP header

• Two interface types supported:FE and FDDI


MultiNodeMultiNodeLoad BalancingLoad Balancing



MultiNode Load Balancing MultiNode Load Balancing (MNLB)(MNLB)

• Next-generation server load balancing

• Unprecedented high availabilityEliminate single points of failure

• Unprecedented scalabilityAllow immediate incremental or large-scale expansion of application servers

• New dynamic server feedbackBalance load according to actual application availability and server workload


MNLB

MNLB—What Is It?MNLB—What Is It?

• Hardware and software solution that distributes IP traffic across server farms

• Cisco IOS router andswitch based

• Implementation ofCisco’s ContentFlow architecture

• Utilizes dynamicfeedback protocol for balancing decisions


MNLB

MNLB FeaturesMNLB Features

• Defines single-system imageor “virtual address” for IP applications on multiple servers

• Load balances acrossmultiple servers

• Uses server feedback or statistical algorithms forload-balancing decisions

• Server feedback contains application availabilityand/or server work capacity

• Algorithms include round robin, least connections, and best performance


MNLB

MNLB FeaturesMNLB Features

• Session packet forwarding distributed across multiple routers or switches

• Supports any IP application: TCP, UDP, FTP, HTTP, Telnet, and so on

• For IBM OS/390 ParallelSysplex environments:

Delivers generic resource capability

Makes load-balancing decisionsbased on OS/390 Workload Manager data


MNLB ComponentsMNLB Components

• Services Manager

Software runs on LocalDirector

ContentFlow Flow Management Agent

Makes load-balancing decisions

Uses MNLB to instruct Forwarding Agents of correct server destination

Uses server feedback protocolto maintain server capacity andapplication availability info

• Backup Services Manager

Enables 100% availabilityfor Services Manager

No sessions lost due to primaryservices manager failure

BackupServiceManager

ServicesManager


MNLB ComponentsMNLB Components

• Forwarding Agent Cisco IOS router and switch software

ContentFlow Flow Delivery Agent

Uses MNLB to communicate with Services Manager

Sends connection requests toServices Manager

Receives server destination from Services Manager

Forwards data to chosen server

• Workload AgentsRuns on either server platforms or management consoles

Maintains information on server work capacity and application availability

Communicates with Services Manager using server feedback protocol

For IBM OS/390 systems deliversOS/390 Workload Manager data

WorkloadAgents

ForwardingAgents


WorkloadAgents

ForwardingAgents

ServicesManager

Client

How Does MNLB Work?How Does MNLB Work?

• Initialization:

Services Manager locates Forwarding Agents

Instructs each Forwarding Agent to send session requests for definedvirtuals to ServicesManager

Locates Workload Agentsand receives server operating and application information


How Does MNLB Work?How Does MNLB Work?

• Session packet flow1. Client transmits connectionrequest to virtual address

2. Forwarding Agent transmitspacket to Services Manager

Services Manager selects appropriate destinationand tells Forwarding Agent

3. Forwarding Agent forwardspacket to destination

4. Session data flows throughany Forwarding Agent routerand switch

The Services Manager is alsonotified on session termination

Client

1

2

3

4


Dispatch Mode of Dispatch Mode of Session DistributionSession Distribution

• Virtual IP address (VIPA) on hosts (alias, loopback)

• Load-balancer presentsvirtual IP address to network

• Load-balancer forwards packets based on Layer 2 address

Uses ARP to obtainLayer 2 address

IP header still containsvirtual IP address

• Requires subnet adjacency since it relies on Layer 2 addressing

ClientClient

IP


LocalDirector1.1.1.1

3.3.3.12.2.2.22.2.2.1

VirtualAddress

RealAddresses

Server Cluster

VIPA 1.1.1.1


Dispatch ModeDispatch Mode

• Benefits

No need to scan past TCP/UDP header, may achieve higher performance

Outbound packets may travel any path

• Issues

Inbound packets must pass through the load-balancer

Ignoring outbound packets does limit the effectiveness of the balancing decisions

Subnet adjacency can be a real network design problem

Client

IP


Server Cluster

Client


MNLBMNLB

• Uses either NAT ormodified dispatch mode

• NATMNLB architecture createshigh availability—no singlepoint of failure

No throughput bottleneck

• Modified dispatch modeUses Cisco Tag Switch network to address across multiple subnets

Inbound and outbound trafficcan travel through any path

Services Manager notifiedon session termination

MNLB

Client

1.1.1.1


BenefitsBenefits



MNLB: The Next GenerationMNLB: The Next Generation

• Unprecedented high availability

Eliminate single points of failure

• Unprecedented scalability

Allow immediate incremental or large-scale expansion of application servers

• New dynamic server feedback

Balance load according to actual application availability and server work load


MNLB

Single System ImageSingle System Image

• One IP address for the server cluster

• Easy to grow and maintain server cluster without disrupting availability or performing administrative tasks on clients

• Easy to administrate clients, only one IP address

• Enhances availability


MNLB

Server IndependenceServer Independence

• MNLB operates independent of server platform

• Server agents operate inIBM MVS, IBM OS/390, IBM TPF, NT, and UNIX sites

• Application-aware load distribution available inall server sites

• Enables IP load distribution for large IBM Parallel Sysplex complexes


MNLB

Application-Aware Load BalancingApplication-Aware Load Balancing

• Client traffic is distributedacross server cluster to thebest server for the request

• Transparent to client

• Allow agent(s) in servers to provide intelligent feedbackto network as basis forbalancing decision

• Uses IBM’s OS/390 Work Load Manager in OS/390 Parallel Sysplex environments

• Application-aware load balancing ensures session completion


MNLB

Total Redundancy—Total Redundancy—Ultimate AvailabilityUltimate Availability

• No single point of failurefor either applications,servers, or MNLB

• Multiple forwardingagents ensure accessto server complex

• Multiple Services Managers ensure load balancing is maintained through failure

• Single cluster address formultiple servers maintainsaccess to applications incase of server failure orserver maintenance


Unbounded ScalabilityUnbounded Scalability

• Scalability limited only by the number and throughput of forwarding agents

• Performance limited only bythe number and throughputof Forwarding Agents

• Forwarding Agents can beadded at any time with noloss of service

• Servers can be added withno network design changes

• NO throughput bottlenecks

• Scales to the largest of Web sites

MNLB


ImplementationImplementationand Road Mapand Road Map



MNLB

Phase One ImplementationPhase One Implementation

• MNLB components

Cisco IOS-based forwarding agents in Cisco 7500, 7200, 4000, 3600, and Catalyst® 5000R Services Manager

Services Manager runs onLocalDirector chassis

LocalDirector hot-standby for phase one backup manager

Workload Agents for IBM OS/390, IBM TPF, NT,and UNIX


Thank YouThank You

Q & AQ & A


1F0_4553_c1 © 1999, Cisco Systems, Inc. Cisco Load Balancing Solutions.

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Transcript of 1F0_4553_c1 © 1999, Cisco Systems, Inc. Cisco Load Balancing Solutions.