BGP - Show next hop address

[eric.lovelace]

All - We have a very large MPLS network that another team manages, We just setup bgp peering at one of our sites and they are advertising all the prefixes they have.

Is there a way to do a show command that tells me what the next hop address is on the far end side? For example I want to do a sh command on the nexus to show me that 172.31.0.0/23 is routed towards 172.30.1.2.

If I run the command sh bgp vrf mpls ipv4 unicast 172.31.0.0/23 on the nexus it gives me the next hop of the HQ Router.

[Akash Agrawal]

It looks very strange requirement to me :) . BGP route carries net-hop information but only for immediate next-hop, not for all the next-hop which got changed in the path. Second thing if both routers are under same autonomous system, you can login to next router and check, if far end router is under different AS, next-hop on that router could be a private ip and can not be passed over BGP updates.

With traceroute to destination, you can check what all hops coming in the path.

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Regards,

Akash

[eric.lovelace]

Yeah I know it's a strange requirement however we don't have access to the routers to look.

A traceroute works but there are allot of sites we don't know all the networks routed towards the firewall...That's what this exercise is really about. We need to know all the networks that are being advertised out of each site.

[Akash Agrawal]

To know which routes belong to which site, we normally use community attribute. You can decide community for each site and while advertising BGP prefixes from the site, add that community. On the other site based on community , you can come to know which prefixes belong to which site.