Reference Guide

166 | Bidirectional Forwarding Detection (BFD)
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2. Enable fast fall-over for BGP neighbors to reduce convergence time (neighbor fall-over command) as
described in BGP fast fall-over.
Establishing sessions with BGP neighbors
Before configuring BFD for BGP, you must first configure BGP on the routers that you want to
interconnect. For more information, refer to Chapter 9, Border Gateway Protocol IPv4 (BGPv4).
For example, the following illustration shows a sample BFD configuration on Router 1 and Router 2 that
use eBGP in a transit network to interconnect AS1 and AS2. The eBGP routers exchange information with
each other as well as with iBGP routers to maintain connectivity and accessibility within each autonomous
system.
Figure 8-15. BFD Session Between BGP Neighbors
Note that the sample configuration shows alternative ways to establish a BFD session with a BGP
neighbor:
• By establishing BFD sessions with all neighbors discovered by BGP (
bfd all-neighbors command)
• By establishing a BFD session with a specified BGP neighbor (
neighbor {ip-address | peer-group-name}
bfd
command)
BFD packets originating from a router are assigned to the highest priority egress queue to minimize
transmission delays. Incoming BFD control packets received from the BGP neighbor are assigned to the
highest priority queue within the Control Plane Policing (COPP) framework to avoid BFD packets drops
due to queue congestion.