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Table Of Contents
LocalAddr RemoteAddr Interface State Rx-int Tx-int Mult Clients
* 2.2.2.2 2.2.2.1 Te 2/1 Up 100 100 3 I
Changing IS-IS Session Parameters
BFD sessions are configured with default intervals and a default role.
The parameters that you can configure are: Desired TX Interval, Required Min RX Interval, Detection Multiplier, and system
role. These parameters are configured for all IS-IS sessions or all IS-IS sessions out of an interface. If you change a parameter
globally, the change affects all IS-IS neighbors sessions. If you change a parameter at the interface level, the change affects all
IS-IS sessions on that interface.
To change parameters for all IS-IS sessions or for IS-IS sessions on a single interface, use the following commands.
Change parameters for all IS-IS sessions.
ROUTER-ISIS mode
bfd all-neighbors interval milliseconds min_rx milliseconds multiplier value role [active
| passive]
Change parameters for IS-IS sessions on a single interface.
INTERFACE mode
isis bfd all-neighbors interval milliseconds min_rx milliseconds multiplier value role
[active | passive]
To view session parameters, use the show bfd neighbors detail command.
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 mode
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 physical, port-
channel, and VLAN interfaces. BFD for BGP does not support the BGP multihop feature.
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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