Service Manual
Prerequisites
Before conguring BFD for BGP, you must rst congure the following settings:
1. Congure BGP on the routers that you want to interconnect, as described in Border Gateway Protocol IPv4 (BGPv4).
2. Enable fast fall-over for BGP neighbors to reduce convergence time (the neighbor fall-over command), as described in
BGP Fast Fall-Over.
Establishing Sessions with BGP Neighbors
Before conguring BFD for BGP, you must rst congure BGP on the routers that you want to interconnect.
For more information, refer to Border Gateway Protocol IPv4 (BGPv4).
For example, the following illustration shows a sample BFD conguration 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 15. Establishing Sessions with BGP Neighbors
The sample conguration shows alternative ways to establish a BFD session with a BGP neighbor:
• By establishing BFD sessions with all neighbors discovered by BGP (the bfd all-neighbors command).
• By establishing a BFD session with a specied BGP neighbor (the 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.
BFD noties BGP of any failure conditions that it detects on the link. Recovery actions are initiated by BGP.
BFD for BGP is supported only on directly-connected BGP neighbors and only in BGP IPv4 networks. Up to 128 simultaneous BFD
sessions are supported
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Bidirectional Forwarding Detection (BFD)