Concept Guide

• Establish sessions with all OSPF neighbors.
ROUTER-OSPF mode
bfd all-neighbors
• Establish sessions with OSPF neighbors on a single interface.
INTERFACE mode
ip ospf bfd all-neighbors
Example of Verifying Sessions with OSPF Neighbors
To view the established sessions, use the show bfd neighbors command.
The bold line shows the OSPF BFD sessions.
R2(conf-router_ospf)#bfd all-neighbors
R2(conf-router_ospf)#do show bfd neighbors
* - Active session role
Ad Dn - Admin Down
C - CLI
I - ISIS
O - OSPF
R - Static Route (RTM)
LocalAddr RemoteAddr Interface State Rx-int Tx-int Mult Clients
* 2.2.2.2 2.2.2.1 Gi 2/1 Up 100 100 3 O
* 2.2.3.1 2.2.3.2 Gi 2/2 Up 100 100 3 O
Changing OSPF Session Parameters
Congure BFD sessions with default intervals and a default role.
The parameters that you can congure are: desired tx interval, required min rx interval, detection multiplier,
and system role. Congure these parameters for all OSPF sessions or all OSPF sessions on a particular interface. If you change a
parameter globally, the change aects all OSPF neighbors sessions. If you change a parameter at the interface level, the change aects all
OSPF sessions on that interface.
To change parameters for all OSPF sessions or for OSPF sessions on a single interface, use the following commands.
• Change parameters for OSPF sessions.
ROUTER-OSPF mode
bfd all-neighbors interval milliseconds min_rx milliseconds multiplier value role [active |
passive]
• Change parameters for all OSPF sessions on an interface.
INTERFACE mode
ip ospf 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 OSPF
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 nal Admin Down packet is sent before the session is terminated.
Bidirectional Forwarding Detection (BFD)
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