Lab 85 - EBGP Multihop

Prerequisites: CCNP level skills.

Topology

Pic. 1 - Topology Diagram.

 Icons designed by: Andrzej Szoblik - http://www.newo.pl

Task 1
Configure EBGP between R1 and R3 in such a way that it can survive either Frame-Relay or HDLC link failure.

Lab Solution

Task 1
Configure EBGP between R1 and R3 in such a way that it can survive either Frame-Relay or HDLC link failure.

R1 Configuration:

!

ip route 172.16.103.0 255.255.255.0 10.1.0.3
ip route 172.16.103.0 255.255.255.0 10.1.13.3
!

router bgp 10
 no synchronization
 bgp router-id 1.1.1.1
 bgp log-neighbor-changes
 neighbor 172.16.103.3 remote-as 30
 neighbor 172.16.103.3 ebgp-multihop 2
 neighbor 172.16.103.3 update-source Loopback0
 no auto-summary

!

R3 Configuration:

!
ip route 172.16.101.0 255.255.255.0 10.1.0.1
ip route 172.16.101.0 255.255.255.0 10.1.13.1
!

router bgp 30
 no synchronization
 bgp router-id 3.3.3.3
 bgp log-neighbor-changes
 neighbor 172.16.101.1 remote-as 10
 neighbor 172.16.101.1 ebgp-multihop 2
 neighbor 172.16.101.1 update-source Loopback0
 no auto-summary

!

Notice!

When EBGP sessions are configured it is assumed that the EBGP peer is directly connected. The TTL is automatically set to 1. This way, session between loopback would not work. EBGP-multihop command changes the TTL (here: 2 hops) allowing session to be established.

Verification:

Pic. 2 - BGP Session Established.

Pic. 3 - Neighbor Details.