At8000 s arquitetura de empilhamento

Marvell Confidential

AT-8000SStacking Architecture


Stacking Overview

• Multiple switches - single management.• Management interfaces:

– Web-based Interface – Command Line Interface (CLI)– SNMP

• One Master, one Backup and multiple regular units. • Each unit has a unique unit ID.• All units must run the same major SW version. • The Stack Master Switch maintains the configuration.• On AT8000S/16 there is only standalone mode.


Stack Topology

• Topologies supported:– Ring – Chain

• Up to six units per stack.• The stack units are connected via 2 Giga ports.

– One port is the “uplink”– Other port is the “downlink”

• One of the units acts as a stack master.• All other units act as slaves. • One of the slaves can also act as a master backup.


Ring and Chain Topology

RING

Chain


Unit ID

• Device Unit ID is unique.• Assigned by the user. • Units ID 1 and 2 are Master Enabled units.• All the other units are regular units.• A boot menu is available during the boot process to select

the Unit ID. • Unit ID is displayed via console, SNMP or Web.• Stack unit number can be 1-6.• In standalone mode - Unit ID is 0.


Unit ID Selection Process

• System provides a boot menu to set unit stack ID (1-6).

• The menu is available during boot process.

• User has 2 seconds to abort image load and to enter the boot menu.

• After device is running, unit ID can be modified by rebooting the device, and using the boot menu.


Unit ID – Boot Menu

Startup Menu

[1] Download Software[2] Erase Flash File[3] Password Recovery Procedure[4] Enter Diagnostic Mode[5] Set Terminal Baud-Rate[6] Stack menu[7] BackEnter your choice or press 'ESC' to exit:


Unit ID – Boot Menu

Stack menu

[1] Set unit number in stack[2] Stack info[3] BackEnter your choice or press 'ESC' to exit:


Viewing Unit ID - LED

• The unit ID is indicated in the device front panel.• LED S# (1 till 6) indicates the unit number.• If all LEDs 1-6 are off, the device operates in Standalone

mode.


Viewing Unit ID - CLI

• A CLI command is available to view unit ID while unit is running.

• User can choose to see unit ID indication on all stack units, or on a specific unit only.


Duplicate Unit ID

• A duplicate ID in a stack can occur if a user assigned the same unit ID to more than 1 unit in the same stack.

• Only one unit will join the stack.• The criteria are:

1. Longest uptime stays.2. Least impact on the stack leaves.

• The LEDs of the unit that does not join will flash.


Standalone Vs. Stack-Mode Operation

• A unit can be in one of the following modes of operation:– Standalone– Stack-mode

• Determined at SW Boot phase.• At factory default, units boot in stand-alone mode.• Standalone units do not run any stacking applications.


Stand Alone Mode

• The Standalone unit…– Does not run the stacking application– Does not participate with any stacking protocol – Does not work as stack unit.

• To change a standalone to a stack unit:– Restart the device– Set the unit ID to 1-6– Connect unit to stack


Stack Unit Operation Modes

• A unit running in stack mode can operate as one of the following: – Master– Regular stack unit– Master Backup


Master Unit Roles

• Manages the entire stack• Responsible for the stack configuration• Runs all protocols• Updates and synchronizes the Backup master


Slave Unit Roles

• Controlled by master• Does not run high level protocols • Will never take role of stack master


Mater Backup Unit Roles

• Runs as slave unit, and in addition…• Configuration files synchronized with master• Monitors existence of master• In case of failure takes over as stack master


Master Election Process

• “Master Enabled” units:– Only two Units at most– UNIT ID is set to 1 or 2

• Master election algorithm will choose one of the two “Master Enabled” units as stack master.

• The election algorithms criteria:– System Up Time– Lowest Unit ID

• The election process:1. Master enable units exchange up time.2. If up time difference between units is less than 10 minutes the

unit with the lowest unit ID is elected.3. If up time difference between units is more than 10 minutes the

unit with the longest UP time is elected.


Force Master

• User can “force” a master-enabled unit to be the master unit.


Master Failure Backup

• Master and Backup maintain a “Warm Standby” – if Master fails, the Backup takes its place.

• “Warm Standby” means full synchronization with static configuration. – Configuration synchronization = running configuration + startup

configuration• Dynamic configuration – is not maintained. • On “switchover”, the Backup master:

– Restarts all protocols – Reconfigures the stack – Configuration synchronization = startup configuration + running

configuration– Flushes all the packet processors tables

• A regular stack unit (unit ID 3-6) will never become a master, even if no master enabled unit exist in stack


Master Failure Backup

• When a unit transitions from “master” state to “backup” state, it is automatically reset.

• If a Master-enabled unit inserted into a running stack…– Is elected as a “Backup Master” (unless it’s uptime is bigger than

the current master)– Already running Master will synchronize the new backup


Stacking ports

• Standard copper GE located on the devices’ rear panel.• Stacking ports are not available to user in “standalone”

mode as regular Network (Giga) ports.


Hot Removal /Unit Failure

• Topology change event is caused by:– Unit failure– Unit hot insertion/extraction – Stacking link failure/extraction/insertion

• Noticed and kept by the master• Stack will continue to operate normally.• Link state of failed unit ports will be set to down state.• No service interruption to units that remained connected.• Backup unit retains the configuration file even if it is

removed from the stack.


Hot Removal / Unit Failure• Unit failure can split the chain.• If there is a Master and a backup in the system each chain

will function separately.• The stack will split into two independent stacks.

Master

Slave

Backup

1

4

5

Slave2

Slave3 SlaveUnit Failure

Stack 1

Stack 2


Newly Inserted Unit

• Stack port table:– Held by the Master – Includes the max number of ports the stack could handle

• For each unit, a range of ports is mapped according to its Unit id.

• Replacing a unit type (same unit ID):– Unit type is identical - the new Unit ports would be reconfigured

exactly as the old one– New unit has lower/higher number of ports - only matching ports

will be reconfigured


1..................... 24

SR248 replace SR224

New Box

Old Box

49.....50

Default Configuration

25 ...26

SR224 replace SR248

1..................... 24

1..................... 24,25.................... 48

New Box

Old Box 49.....50

25 ...26

Different types of unit replacement

Stack Topology Changes

Stack 1Stack 2

48……25 24……1Stack 1Stack 2

Stack 1Stack 2

Stack 1Stack 2

25, 24

48 ports device replaces 24 ports device 24 ports device replaces 48 ports device


Stack Configuration

• Configuration files are changed only throughexplicit user action, and are not automaticallymodified when units are added, removed,reassigned unit ID’s or toggled from stack-modeoperation to standalone operation and back.

• The system “remembers” all configurationinformation, even if it applies to ports/units thatwere removed from the stack.

• Only ports physically present are displayed in the Browser-based GUI, and thus only ports physically present may be configured using this interface.


Stacking - CLI Commands


CLI Commands – Force Master

• Use the following Global Configuration mode command to force a selection of specific unit to be stack master. Use the “no” form of the command to return to default configuration:

stack master unit unitno stack master


CLI Commands – Show Stack

• Use the following User EXEC mode command to display stack status information:

show stack [unit]


Stack Related CLI commands

• Use the following Privileged Exec mode command to boot entire stack or specific unit in stack:

stack reload [unit]• Use the following Privileged Exec mode command to define

the image to use at startup for stack units:boot system [unit unit] {image-1 | image-2}

• Use the following Privileged Exec mode command to copy a boot or image file from stack master to one of the stack units:

copy image unit://unit_number/imagecopy boot unit://unit_number/boot• Use “*” to copy to all units:copy image unit://*/image


CLI Command - Show Stack

console# show stackUnit Address Software Master Uplink Downlink Status--------------------------------------------------------------------------------1 00:00:b0:10:11:00 1.0.0.0 Enabled 3 2 master2 00:21:03:08:52:30 1.0.0.0 Enabled 1 3 backup3 00:00:28:02:05:11 1.0.0.0 Disabled 2 1 slave


CLI Command - Force Master

console(config)# stack master unit 2console(config)#-----------------------------------Unit rebooted: switchover to backup-----------------------------------

******************************************************************* SYSTEM RESET *****************…


CLI Command - Force Master (Show)

console# show stackUnit Address Software Master Uplink Downlink Status--------------------------------------------------------------------------------1 00:00:b0:10:11:00 1.0.0.0 Enabled 3 2 backup2 00:21:03:08:52:30 1.0.0.0 Forced 1 3 master3 00:00:28:02:05:11 1.0.0.0 Disabled 2 1 slaveconsole#console# show running-configinterface ethernet 2/e24ip address 30.1.1.1 255.0.0.0exitstack master unit 2


CLI Command - Copy Command

console# copy image unit://*/image01-Jan-2000 01:44:59 %COPY-I-FILECPY: Files Copy - source

URL flash://image destination URL Unit all flash://image!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!01-Jan-2000 01:46:59 %COPY-W-TRAP: The copy operation was completed successfully

!Copy: 4239439 bytes copied in 00:02:00 [hh:mm:ss]

At8000 s arquitetura de empilhamento

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