Flapping HSRP

CucumberCucumber Member Posts: 192
Hi guys, I know this is not a troubleshooting forum, but just thought I may share my problem with you and see what you think.

I have been having problems with a cat 6503 that is one of the core/distribution switches in the network. It is a basic switch block, two core/distribution switches connected to each other, with several access switches hooked up to them, by the way the access switches have no redundant conection to the core/distribution switches.

The problem

HSRP flapps spontaneusly two times a week, this 6503 starts claiming it is active, then it realizes the other core switch is up, and goes back to standby, then it claims its active again, and so on and on . The only way I can solve it is restarting the offending switch.

What have I done

I have done my homework, I have checked there are no physical problems on the link between the core switches, I replaced the single link that was connecting them with an etherchannel, using different FO cables and different ports on different cards, just to rule out a physical problem. show interface shows no errors or interface resets.

Next, I made sure there are no STP loops, I even run some spantree debugs when this flapping happened without any STP instabilities reported.

I also removed the preempt option, and still getting the flapping.

show process cpu history reports zero cpu utilization

Traffic is low, reported from show interface.

Any ideas?
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