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New Member

3750G stackwise L3 recovery time?

Hi Folks,

Does anyone know what the recovery time would be if the stackmaster fails? In this case, the stack is running some L3 features and routing etc...

The time i am interested in is the time from the failure, to the time that all the L3 next hops become available with the new master back online.

TIA

Alan

2 REPLIES
New Member

Re: 3750G stackwise L3 recovery time?

All stack members share the routing table, and can continue routing traffic.

This is what documentation say, I have not tried yet.

"If a stack master fails, the stack detects that the stack master is down and elects one of the stack members to be the new stack master. During this period, except for a momentary interruption, the hardware continues to forward packets with no active protocols.

However, even though the switch stack maintains the hardware identification after a failure, the routing protocols on the router neighbors might flap during the brief interruption before the stack master restarts."

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_50_se/configuration/guide/swiprout.html#wp1427489

Guido

Bronze

Re: 3750G stackwise L3 recovery time?

* Make sure you implement NSO/SSF

* In a routing stack , use the "stack-mac persistent" feature. This way the stacks mac address (default gateway etc) will not change during master failover.

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_44_se/configuration/guide/swstack.html#wp1206500

* Also carefully look at your other L3 links, so you don't blackhole any traffic if one switch in a stack fails and the rest stays up.

Then convergence should be fairly quick

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