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Community Member

Network Hiccup -- HSRP recalculate symptom

Periodically, my network of 3 Catalyst 5500 switches with RSM's will "hiccup". This will cause some applications on the network to lose connectivity. When the network hiccups I see HSRP recalculate. I have HSRP set up between the RSM's in the 5500's. Recalculation takes just a few seconds, but enough to blow away some applications. I have tried a few suggestions from TAC but still cannot get rid of the hiccup. Latest attempt was to replace some perceived faulty hardware that may have been dropping packets. Did not work. Next recommended TAC step is to put code on all 5500's at level 5.5.11. I'm still not confident that this will help. Are there any fresh ideas out there?

Related: Sometimes I see an HSRP recalculation on a couple of VLAN's with no adverse impact on the network. Is it to be expected that in the normal operation of things that some HSRP recalculations will occur?

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Community Member

Re: Network Hiccup -- HSRP recalculate symptom

There are a few ways that HSRP will fail over.

1. HSRP secondary router does not receive hellos for the specified time period (default 10 seconds).

2. Primary interface priority drops below priority of secondary *and* secondary has STANDBY PREEMPT set.

3. Primary router sends "resign" to secondary. (related to #2 above)

If you do a "debug stand" on your primary and secondary, you should be able to determine which of the three occured.

HSRP does not flap as a rule... something is affecting it.

Mick.

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