configuration for HSRP

Unanswered Question
Oct 2nd, 2007

Hi Expert,

I have a few question regarding the HSRP configuration. From the Internet, I found out that most of the HSRP example involve 2 routers. Let say if I have 3 fast ethernet card in a router. Can I use only one router to do a HSRP for link redundancy?

Thanks & Regards,

Wei Wei

I have this problem too.
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Kevin Dorrell Tue, 10/02/2007 - 18:46

No you cannot, because for HSRP to be useful you would need to put them on the same subnet, and two interfaces on the same subnet is not allowed.

However, if you are talking about a layer-3 switch like the 3560, you can bundle two links as a layer-3 etherchannel and treat them as a single router interface. That would give you layer-3 link redundancy.

But I don't think you can do that on a router (yet).

Kevin Dorrell


paul.matthews Tue, 10/02/2007 - 23:51

I can thik of a way that you may be able to do it, but before I say what that is, I need to stress that I am mentioning this as an academic point, I recommend that you do NOT do this.

Create a BVI on the router and bridge that to the two router interfaces. You would not need HSRP, as you would be using spanning tree to do the failover. If doing that I would also force the router to be the root bridge.

I suspect this may add unnecessary complexity to the network though, and overall I doubt it would add to resilience.

If you really want resilience, add another router.

da_heizhu Wed, 10/03/2007 - 01:14

HSRP is more to provide hardware redundancy. When link redudancy is needed and hardware redundancy is not a concernce, HSRP is not necessary. Routing protocols provides pretty good layer 3 link redundancy whereas Spaning tree, ehterchannel provide pretty good layer2 link redundancy.


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