Don Provan | 15 Aug 21:01 2005

RE: RE: VRRP Flapping Question

>Hopefully this is better late than never. We have performed some
>testing with both HSRP and VRRP. We used some proprietary
>capabilities with protocols which permitted setting the advertisement
>timer (and the hello timer for HSRP) to millisecond values. With
>HSRP, we found that if the hold timer was set such that when three
>hellos were missed, the protocol would failover - HSRP was very
>unstable (i.e., flapping). If we set the hold timer such that more
>hellos had to be missed, the protocol became more stable and less
>flapping occurred. With VRRP, you don't have the option of missing
>more advertisement intervals. Thus the solution was to increase the
>time of the advertisement interval.

Sorry for coming in late on this, but it sounds like the
original timeout was too small, and when you increased it
either by increasing the packet count or by increasing the
interval, the flapping stopped. Did you see something that
suggests that when the total timeout is held constant, a
shorter interval (i.e., more packets) works better?

-don provan
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