How to advertise the IBGP learned routes to another IBGP peer.

[frank.lu]

The IBGP peers are not fully meshed, so I had "no sync" enabled and set the next-hop-self, but the routes learned from IBGP peer A is not advertising to IBGP peer B?

Is there any way to make it working?

[cdfowlie · Accepted solution]

If the peers are not going to be fully meshed, you can solve this issue using a route reflector. IBGP assumes a full mesh by default, so it does not pass on routes learned FROM an IBGP peer TO another IBGP peer.

To do this, on your router, issue the command

neighbor B.B.B.B route-reflector-client

Where B.B.B.B is the IP address of the router that you want to learn the routes. Then you will pass on all IBGP-learned routes to router B. "next-hop-self" is not going to modify this behaviour. It is used to re-write the next-hop attribute travelling through your AS. By default this attribute would only be changed at the boundary between 2 AS's (between EBGP peers), and the configured IGP such as OSPF, IS-IS, or EIGRP would be used to reach the exit point of the AS (the next-hop for the BGP route).

HTH

-Colin