Service Manual

Disabling BFD for IS-IS
If you disable BFD globally, all sessions are torn down and sessions on the remote system are placed in a
Down state.
If you disable BFD on an interface, sessions on the interface are torn down and sessions on the remote
system are placed in a Down state. Disabling BFD does not trigger a change in BFD clients; a final Admin
Down packet is sent before the session is terminated.
To disable BFD sessions, use the following commands.
• Disable BFD sessions with all IS-IS neighbors.
ROUTER-ISIS mode
no bfd all-neighbors
• Disable BFD sessions with IS-IS neighbors on a single interface.
INTERFACE mose
isis bfd all-neighbors disable
Configure BFD for BGP
In a BGP core network, BFD provides rapid detection of communication failures in BGP fast-forwarding
paths between internal BGP (iBGP) and external BGP (eBGP) peers for faster network reconvergence. BFD
for BGP is supported on 1GE, 10GE, 40GE, port-channel, and VLAN interfaces. BFD for BGP does not
support IPv6 and the BGP multihop feature.
Prerequisites
Before configuring BFD for BGP, you must first configure the following settings:
1. Configure 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 configuring BFD for BGP, you must first configure 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 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.
Bidirectional Forwarding Detection (BFD)
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