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HSRP sessions flapping

Hi folks,

Anybody ever run into a situation where HSRP sessions between 2 neighbours would flap inexplicably?

My 2 switches are connected via a GEC dot1q trunk with 4 members. All member interfaces are clean aside from a few overruns.

I have 25 HSRP vlans on my switch and 4 of them will flap at various times during the day, typically at the same time and the state changes will occur within 1 second. The 4 vlans that flap are all in standby and the active neighbour is configured with a higher priority and for preempt.

Any ideas?

2 REPLIES
Silver

Re: HSRP sessions flapping

Refer to the troubleshooting giude for resolving the HSRP flapping issue.

http://www.cisco.com/en/US/products/hw/switches/ps663/products_tech_note09186a00801434de.shtml#subtopic1k

Re: HSRP sessions flapping

Hello Matt,

I think what you are asking is: why HSRP is flapping eventhough the vlans that are flapping are in standby mode?

HSRP standby will change to active whenever they stop receiving hello packets from the active router.

So, I'm not sure what you mean by vlan flaps, but for some reason the standby router is not receiving hellos from the active router from time to time. So you need to look for connectivity issues or bridges in the network (for duplicate or bad hello packets).

" The error you are seeing signify the loss of HSRP hellos between the peers. When you troubleshoot this issue, you must verify the communication between the HSRP peers. A random, momentary loss of data communication between the peers is the most common problem that results in these messages.

There are several possible causes for the loss of HSRP packets between the peers. The most common problems are physical layer problems or excessive network traffic caused by spanning tree issues.

"

HTH,

if it does, I'd appreciate if you rate this post.

Vlad

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