Connectivity Guide

In this example OSPF is enabled in non-default VRF red. BFD is enabled globally at the router OSPF level and all the interfaces associated
with this VRF OSPF instance inherit the global BFD conguration. However, this global BFD conguration does not apply to interfaces in
which the interface level BFD conguration is already present. Also, VLAN 200 takes the interface level BFD conguration as interface-level
BFD conguration takes precedent over the global OSPF-level BFD conguration.
Changing OSPFv2 BFD 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.
NOTE: By default, OSPF uses the following BFD parameters for it's neighbors: min_tx = 200 msec, min_rx = 200 msec, multiplier
= 3, role = active. If BFD is congured under interface context, that will be given high priority.
To change parameters for all OSPFv2 sessions or for OSPF sessions on a single interface, use the following commands:
1 Change parameters for OSPF sessions.
bfd all-neighbors interval milliseconds min_rx milliseconds multiplier value role [active |
passive]
ROUTER-OSPF Mode
2 Change parameters for all OSPF sessions on an interface.
ip ospf bfd all-neighbors interval milliseconds min_rx milliseconds multiplier value role
[active | passive]
INTERFACE CONFIGURATION Mode
Disabling BFD for OSPFv2
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.
To disable BFD sessions, use the following commands:
1 Disable BFD sessions with all OSPF neighbors.
no bfd all-neighbors
ROUTER-OSPF Mode
2 Disable OSPFv2 at interface level using the following command:
ip ospf bfd all-neighbors disable
INTERFACE CONFIGURATION Mode
To re-enable BFD, disabled the interface alone using the following commands:
• no ip ospf bfd all-neighbors command
• ip ospf bfd all-neighbors
Congure BFD for OSPFv3
BFD for OSPFv3 provides support for IPv6:
Layer 3
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