How to find out who originated a OSPF route?

[caobo1020]

Hi Guys,

Maybe it's a simple question for you, how to find out which router originated a OSPF route?

Example: there are five OSPF routers R1, R2, R3, R4, and R5 in area 0. They have the same OSPF DB in the memory. When I do a 'sh ip route x.x.x.x', the outputs indicates it's learned via OSPF, the quesiton is how can I konw which router is the originator for the route x.x.x.x.

Thanks

Bo

[Peter Paluch]

Hello Bo,

If you enter the show ip route x.x.x.x command, you will get an output similar to this:

Router# show ip route 0.0.0.0 0.0.0.0

Routing entry for 0.0.0.0/0, supernet

  Known via "ospf 1", distance 110, metric 24, candidate default path

  Tag 1, type extern 1

  Last update from 10.10.7.158 on Vlan7, 4d12h ago

  Routing Descriptor Blocks:

  * 10.10.7.158, from 10.10.7.1, 4d12h ago, via Vlan7

      Route metric is 24, traffic share count is 1

      Route tag 1

Observe the two highlighted addresses. Here, 10.10.7.158 is the IP address of the next hop towards the destination, and 10.10.7.1 is the OSPF Router ID of the router who originated this route. In this case, it would be the 10.10.7.1 router who injected this default route into the OSPF domain. It is very helpful to know the OSPF Router ID for each router in your network - this way, you can quickly know which router it is.

Best regards,

Peter

[caobo1020]

Hi Peter,

I am running the "show ip route" command from a NX-OS. I see the next hop info from the output, however, I don't see any router ID from output.

r1# sh ip route 10.38.0.1

10.38.0.1/32, ubest/mbest: 2/0

    *via 10.32.16.17, Po3, [110/6667], 7w0d, ospf-1, intra

    *via 10.32.16.65, Po32, [110/6667], 7w0d, ospf-1, intra

Bo