I have 2 6509's with dual sup 720's in each participating in a standby group (several actually-1 per vlan)When failing over the sup engine in the active router the HSRP apparently switches active routers. However approximately 1/2 the time the active router reverts to the original although there is no preempt configured. I can do a sh standby on the standby router and it shows a state change but it is still the standby. The other half of the time it becomes the active router, passes all traffic apparently but I cannot ping or telnet the virtual IP from anywhere except from itself. I am confused. Any help would be appreciated.
Are you using (m)hsrp or glbp?
I would (pls be aware of the impact) debug standby error or debug standby event to see what the reported cause is. Does logging indicate a possible hardware failure? Are you using a dynamic routing protocol? Does you routing protocol converge which causes this problem?
Can you share a sh standby brief?
I will try to share upload the standby brief. I should have mentioned i did debug on errors and events, if I can do the test again I will put up the debug events also. Basically on the errors debug there was none.On the events although I didn't follow everything I am pretty certain it all looked good. I am running OSPF but it is basically a 1 router (with hsrp redundancy). I am not sure what is (m)hsrp or glbp, but to explain I configured using the default "standby
mhsrp is multi-group hsrp. Normally, using hsrp on 2 routers, (a) is active and (b) is standby for a single hsrp group. If you create an extra group, (b) can be made active and (a) standby. You will have 2 gateway addresses then. gateway load balancing protocol (glbp) is the newer alternative for mhsrp.
sh standby internal can give a good explanation too. If you run hsrp with the same group number on different routers, but in the same subnet, they might complain about eachother.