Comments on: When to use preempt in HSRP?

By: Muhammad Aftab Anwer

Muhammad Aftab Anwer — Mon, 21 Nov 2011 14:10:26 +0000

Let’s imagine the following situation.
we have two switches sw1 and sw2
We intend for SW1 to be the active HSRP member. We DON’T configure the preempt option on SW1. We boot SW2 three (3) minutes earlier than SW2. When SW1 boots up, without the preempt command on SW1, it won’t become active, even if it has the higher priority configured for it. If we change the configuration and add the preempt to SW1, it will then become active, only because it has the higher priority of the 2 HSRP members.

regards

Muhammad Aftab Anwer
ref:Keith

By: David Sudjiman

David Sudjiman — Thu, 06 Jan 2011 23:09:41 +0000

@ Jason, Noted and Thanks!

By: Jason

Jason — Thu, 06 Jan 2011 20:07:11 +0000

That document is either wrong or worded incorrectly. When the active router fails, the router of next highest priority will become the active router.

However, without the preempt command on the “main” or primary router, that router will not resume it’s active status unless the engineer manually preempts the router.

I also recommend using a preempt timer. This will help prevent flapping between two routers if a link becomes unstable.