04-29-2013 07:43 AM - edited 03-07-2019 01:05 PM
Hello all,
I have the following scenario:
- Two router configured with HSRP in LAN interface.
- HSRP preempt is configured (300 seconds delay).
- The HSRP ex-standby router is active, after a while the HSRP ex-active router goes up.
- Then, the tracked link on HSRP ex-standby router goes down before the preempt delay is finished.
In these conditions, I have the doubt about the HSRP behaviour, I mean, if the HSRP active router waits the preempt delay before takes over or not.
Thank you very much.
Best regards.
Paolo
Solved! Go to Solution.
04-30-2013 04:21 AM
Paolo
Yes if the LAN interface of router B fails then the HSRP hello messages are not transmitted, just like if the whole router goes down. And when router A realizes that the HSRP hello messages have stopped then it knows that it has lost its HSRP peer and will immediately take over as the HSRP active router.
HTH
Rick
04-29-2013 10:54 AM
Paolo
I am not sure that I fully understand your question so I would like to make sure that my understanding is close to what you meant. I think I understand that you have router A that is configured with higher priority to be the active router in HSRP and have router B that is configured with lower priority to be the standby router. I believe that you indicate that router A failed and that router B took over as active router. I believe that router A has returned to service and with higher priority will preempt and take over as active router, after the preempt delay. I believe that you indicate that a tracked interface on router B goes down and the priority of router B is even lower than it was. And the question is whether that has any change in router A and its becoming active.
If my understanding of your question is correct then the answer is that router A will continue to wait until the delay period of 300 is completed before it becomes the active router.
Note that it would be different situation if router B fails and goes out of service. In that case router A immediately becomes the active router. But if router A is going to preempt the currently active router then it will wait for the complete delay period.
I found this article about HSRP preempt delay to be helpful. You might be interested in what it has to say.
HTH
Rick
04-30-2013 12:30 AM
Hello Rick,
Thank you for your quick answer. You get the point.
I have the last doubt. If on router B the LAN interface fails the behaviour is like the case in which the router B goes down. Isn't it?
Best regards.
Paolo
04-30-2013 04:21 AM
Paolo
Yes if the LAN interface of router B fails then the HSRP hello messages are not transmitted, just like if the whole router goes down. And when router A realizes that the HSRP hello messages have stopped then it knows that it has lost its HSRP peer and will immediately take over as the HSRP active router.
HTH
Rick
04-30-2013 07:07 AM
Hello Rick,
Thanks a lot.
Kind Regard.
Paolo
04-30-2013 10:11 AM
Paolo
I am glad that my explanation was helpful. Thank you for using the rating system to mark this question as answered. It makes the forum more useful when people can read a question and can know that an answer was found. Your marking has contributed to that process.
HTH
Rick
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide