A route is advertised from AS 65221 to AS 65432 using EBGP. The route is active and reachable on R3, but does not appear as an active route on R1 and R2. R3 has an export policy applied to its IBGP group matching on routes from R4, but does not have a then criteria specified. Which policy action should router R3 configure to make this route visible on routers R1 and R2?
A.
then next-hop self
B.
then accept
C.
then announce
D.
then resolve-recursive
We can redistribute the external network into the IGP.
We can advertise the external network into the IGP (presumably as a passive interface).
We can configure the next hop self parameter on the edge router on the receiving AS’s internal neighbor relationships.
Being aware of all three methods is important to understanding the options available to you should you need to configure “RFC-compliant” BGP. My personal preference is setting the next-hop-self parameter on each of the edge router’s IBGP connections, thus ensuring a reachable next hop without increasing the size of the IGP table. It is not necessarily going to maintain the most optimal routing path to exit the AS (due to the default BGP path selection process being inferior to that of an IGP) but it consistently works to establish connectivity.
The next-hop-self option as it’s simplest and easiest to configure. Also, one of the method for eBGP peering is to peer with loopback interfaces and enabling ebgp-multihop option. I like this feature more then configuring directly connected physical interfaces. It allows you to establish connections over redundant paths without making any changes when one of the path goes down etc.
0
0