HSRP Preempt on both routers.

[Shri612]

Hi ,

Why do i need  or in which senarios i need preempt to be configured on both routers.

Preempt allows the router with it configured to take over the active role if it has a higher priority than the other router.

 I heard it is requried  when we are tracking  interface .

But if you are decreasing the priority based on an external event  for Example am  tracking an interface on the active router. The active router has a priority of 120 and the standby 110. The tracked interface goes down and the active router decrements it's priority by 20 and will move to standby . Since preempt is configured on Active router , once active router is up it goes back to active router.

Without using preempt on the secondary router it worked as expected during interface tracking . Could you please help on this?

[paul driver]

Hello

In theory when tracking had initiated and decremented the primary hrsp rtr without preemption on the secondary router  failover shouldn't occur even with if the secondary rtr now having the higher priority.

The reason being is that when the primary decrements its priority the secondary rtr should not receive any hello message(coup) stating a lower priority from the active primary rtr.

Can you post the output for both rtrs please:

show standby 

[Joseph W. Doherty]

As Paul notes, without preempt, the secondary shouldn't take over just because it has the higher priority. Without preempt, the secondary should only take over if the active router "disappears".