HSRP preempt delay issue

[ks0309]

Hi,

thank you for your kind answer in advance.

I would like to know about two things.

1. what is the first IOS release which have HSRP

preempt delay option?

2. I know that the hsrp preempt function is implemeted in usual environment without the delay option.

So, when the backbone(with high priority and preemption without delay option and STP root) was

rebooting for some reasons, and during the restoration time, clients must go through out of service nearly 30 seconds.

I think there are TWO solutions

1.remove the preempt command

2.add "delay" option value to the preempt command

Which one do you recommend for this situation?

[pradeepde]

The standby preempt command enables the Hot Standby Router Protocol (HSRP) router with the highest priority to immediately become the active router. Priority is determined first by the configured priority value, and then by the IP address. In each case, a higher value is of greater priority. When a higher priority router preempts a lower priority router, it sends a Coup message. When a lower priority active router receives a Coup message or a Hello message from an active, higher priority router, it changes to the Speak state and sends a resign message.

For more information : http://www.cisco.com/warp/public/619/6.html

[limtohsoon]

Hi,

The "standby preempt" command is used to configure a router to preempt or immediately take over the active role if its priority is the highest AT ANY TIME.

My usual practice is I configure preemption on all the routers participating in the HSRP group (of course, each would have different predetermined priority values), in case I have to change their priorities in the future, I can be assured that preemption will work correctly.

By the way, anyone knows how long it takes for a router to go thru the HSRP state sequence of Disabled->Init->Listen->Speak->Standby->Active ?

Thank you.

B.Rgds,

Lim TS

[DouglasScott99]

Yes, but no, you will still have to do some reading.

HSRP waits for a number of 'lost' hello packets before doing it's thing. I seem to recall that the hello interval and the number of hellos it allows to be missed is configurable.

OK, I looked it up.

It is not EXACTLY like that but is close.

Search for for "hsrp timers".

It would be shocking of the timers were different in different versions so I wouldn't worry about that.

[marcbutler]

HI

On the issue of timers and missed HELLOs. The defaults are that a router in a STANDBY group will send out HELLO's every 3 seconds. If a router has not heard a HELLO from it's ACTIVE router in that group equal to the period of 3 HELLO's, then it will start the process of going into ACTIVE (if it is the next eligible router). Basically, the default for a router to wait before it will go ACTIVE in normal deployments is 10 seconds (3 times 3 seconds for HELLO interval, plus 1 second for any minor delays within the infrastructure).

You mentioned it was taking thirty seconds to become active. Either you have adjusted your HSRP HELLO timers to 10 seconds. Or, it sounds like there are some spanning tree issues that may be preventing propogation of these HELLO to their destination.