Question

A service provider runs IBGP between PE1 and PE2 (both in AS 65100) over an internal /30 link. PE1 has an EBGP session to a customer router in AS 65200 over the subnet 203.0.113.0/30. After the customer advertises 198.51.100.0/24, PE2 receives the prefix in its BGP table but marks it as inaccessible, and the route never enters the RIB. The IGP on the provider core does not carry the 203.0.113.0/30 subnet. Which configuration on PE1 resolves the issue?

Accepted Answer

Configure 'neighbor <PE2> next-hop-self' on PE1 under the IBGP session

Answer

Configure 'neighbor <customer> next-hop-self' on PE1 under the EBGP session

Answer

Enable 'bgp default local-preference 200' on PE1 for the customer prefix

Answer

Configure 'neighbor <PE2> ebgp-multihop 2' on PE1 under the IBGP session