How to bring CSM module from Active to Standby.

Unanswered Question
Oct 20th, 2009

Currently CSM1 is active and CSM2 is standby.

All the traffic currently flowing though the CSM1 which is currently Active which is perfectly correct. Now we Need to check the redundancy behaviour by bringing down the CSM1

and make CSM2 as active so that all the traffic should flow though it.

Can someone let me know how to bring the Active CSM1 to standby so that CSM2 to become Active and CSM1 to go standby??

Do I need to do something on CSM1? or on the Cat6500.

NOTE: 2 CSM are in 2 different Cat 6500 Chasis.

Thanks in advance.

REgards,

Neha.

I have this problem too.
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Syed Iftekhar Ahmed Tue, 10/20/2009 - 09:43

on Cat6500 with Active CSM you can power off the ACtive CSM which will cause Standby CSM to become active

"no power enable module X"

where X is the slot in which CSM is installed.

If you just want to switch roles and do not want to reload/restart the CSM then

use

"clear module csm ft active"

for more details

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/cfgnotes/csm_3_2

/cmd_ref/cmdref.pdf

Hope this helps

Syed Iftekhar Ahmed

nehakulsum Mon, 10/26/2009 - 07:24

Hi Syed,

I dont want to power off the module. And how can I use the clear module command as I have enabled the prempt on my csm and the pdf documents says dont use it if you are configured prempt command.

Any comments from you on this???

Regards,

Neha

Syed Iftekhar Ahmed Mon, 10/26/2009 - 11:03

You will have to disable preemption before using this command.

If you do not then due to high priority value the Currently active CSM will preempt the active status back from the standby after a switchover.

Thanks

Syed Iftekhar Ahmed

nehakulsum Tue, 10/27/2009 - 03:10

Hi Syed,

What happens if I increase the priority on CSM 2 will it take over the role of Active? If yes will there be any impact ? Will all the active sessions from CSM1 will be pour down to CSM2????

Thanks in advance,.

Regards,

Neha,.

sachinga.hcl Wed, 10/28/2009 - 15:17

HI Neha,

Connection redundancy prevents open connections from ceasing to respond when the active CSM fails and the standby CSM becomes active. With connection redundancy, the active CSM replicates forwarding information to the standby CSM for each connection that is to remain open when the active CSM fails over to the standby CSM.

Have you configured connection redundancy like as follows,:

Command Purpose

Step 1

Router# configure terminal

Enters router configuration mode.

Step 2

Router(config)# no ip igmp

snooping

Removes IGMP snooping from the configuration.

Step 3

Router(config-module-csm)#

vserver virtserver-name

Identifies a virtual server and enters the virtual server submode.

Step 4

Router(config-slb-vserver)#

virtual ip-address [ip-mask]

protocol port-number [service

ftp]

Configures the virtual server attributes.

Step 5

Router(config-slb-vserver)#

serverfarm serverfarm-name

Associates a server farm with a virtual server.

Step 6

Router(config-slb-vserver)#

sticky duration [group

group-id] [netmask

ip-netmask]

Ensures that connections from the same client use the same real server.

Step 7

Router(config-slb-vserver)#

replicate csrp sticky

Enables sticky replication.

Step 8

Router(config-slb-vserver)#

replicate csrp connection

Enables connection replication.

Step 9

Router(config-slb-vserver)#

inservice

Enables the virtual server for load balancing.

Step 10

Router(config-module-csm)# ft

group group-id vlan vlanid

Configures fault tolerance and enters the fault-tolerance submode.

Step 11

Router(config-slb-ft)#

priority value

Sets the priority of the CSM.

Step 12

Router(config-slb-ft)#

failover failover-time

Sets the time for a standby CSM to wait before becoming an active CSM.

Step 13

Router(config-slb-ft)#

preempt

Allows a higher priority CSM to take control of a fault-tolerant group when it comes online.

This example shows how to set fault tolerance for connection redundancy:

Router(config-module-csm)# vserver VS_LINUX-TELNET

Router(config-slb-vserver)# virtual 10.6.0.100 tcp telnet

Router(config-slb-vserver)# serverfarm SF_NONAT

Router(config-slb-vserver)# sticky 100 group 35

Router(config-slb-vserver)# replicate csrp sticky

Router(config-slb-vserver)# replicate csrp connection

Router(config-slb-vserver)# inservice

Router(config-slb-vserver)# exit

Router(config-module-csm)# ft group 90 vlan 111

Router(config-slb-ft)# priority 10

Router(config-slb-ft)# failover 3

Router(config-slb-ft)# preempt

Router(config-slb-ft)# exit

If you have done your configuration like this then this is a configration for connection redundancy.

Kindly check if your configuration is similar to the above .

Kindly consult the following URL in this regard:

http://www.cisco.com/en/US/docs/interfaces_modules/services_modules/csm/3.2/configuration/guide/redun.html#wp1037627

Sachin Garg

Syed Iftekhar Ahmed Thu, 10/29/2009 - 02:14

Neha

You are right.

If premption is on and you increase the priority then the csm with highest priority will take over the active role.

Connections are replicated provided connection replication is configured

Your configs need to have "replicate csrp connections" under vserver configuration for connection repliaction

and "replication csrp sticky" for sticky table replication.

If configured, Active CSM copies its connection table and sticky table over to the backup CSM.

In the case of failover, the backup CSM knows what connections were going to which servers.

However there is a possibility if Active CSM is in middle of transmitting connection info and failover happens then few

connections will be lost. Stanby CSM needs complete connection information and cannot serve existing connections if

it has partial information about any connection.

HTH

Syed Iftekhar Ahmed

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