Adding Loopback interface for branch routers

[Neri Gary Cacatian]

Hi,

I have several branch routers that i want to add a loopback interface for managament purposes. I am currently using ospf as my routing protocol.

Will the rotuer-id be updated accordingly and will there be any effect on my ospf routing?

Thanks.

[Reza Sharifi · Accepted solution]

Hi,

No, the router id will not change unless you clear the OSPF process. So, this will cause an outage to your environment and should be done during a maintenance window.

from the ospf document:

OSPF automatically prefers a loopback interface over any other kind, and it chooses the highest IP address among all loopback interfaces. If there are no loopback interfaces present, the highest IP address in the router is chosen. The OSPF cannot be directed to use any particular interface. Once the router ID is elected, it does not change unless the OSPF process restarts or the router is reloaded.

http://www.cisco.com/c/en/us/support/docs/ip/open-shortest-path-first-ospf/23862-duplicate-router-id-ospf.html

HTH