Configuring same IP address on 2 different routers, one interface being shutdown on second router

[jordanahiti]

Hello,

I would like to know if there is any risk configuring the same IP address on an interface from one Cisco router to another, the only difference being that one interface is shutdown on the second router and acts as a backup in case the first one fails.

As traffic is passing through the second router as well, I am wondering if it could respond to ARP request if it finds the IP address of its shutdown interface in the ARP request.

Thank you,

Jordan

[balaji.bandi]

why not considering deploying HSRP, so Virtual IP remains the same?

[mlund]

Hi

Balaji Bandi has given you the most preferable way to do, because it will be automatic redundancy.

With the same address in both routers and one of them in shutdown, is manual redundancy and that will also work.

And as a direct answer to your question, no, the router will not use this interface, and will not answer on arp requests.

/Mikael

[Richard Burts]

We do not know enough about this environment and about the requirements to be able to be sure what is a good solution. When I read this in the original post "I would like to know if there is any risk configuring the same IP address on an interface from one Cisco router to another". If an interface address is to be used on a different router it suggests to me that the subnet associated with that interface address will also be used on the different router. And in that case HSRP does not solve the problem.

The original post asks this question " if it could respond to ARP request if it finds the IP address of its shutdown interface in the ARP request." and I believe that we can answer that question. If the interface is shut down then the router would not respond to an arp request for that address.