ospf bfd
Function
The ospf bfd command enables the BFD on the specified interface enabled with OSPF, or sets the parameter values of a BFD session.
The undo ospf bfd command deletes the BFD on the specified interface, or restores the default parameter values of a BFD session.
By default, BFD is not enabled or configured at OSPF interface view.
Format
ospf bfd enable
undo ospf bfd enable
ospf bfd { min-rx-interval receive-interval | min-tx-interval transmit-interval | detect-multiplier multiplier-value } *
undo ospf bfd { min-rx-interval [ receive-interval ] | min-tx-interval [ transmit-interval ] | detect-multiplier [ multiplier-value ] } *
Parameters
| Parameter | Description | Value |
|---|---|---|
| enable | Enables BFD. | - |
| min-rx-interval receive-interval | Indicates the minimum interval at which BFD packets are received from the remote end. | The value is an integer ranging from 10 to 2000, in milliseconds. The default value is 1000 milliseconds. |
| min-tx-interval transmit-interval | Indicates the minimum interval at which BFD packets are sent to the remote end. | The value is an integer ranging from 10 to 2000, in milliseconds. The default value is 1000 milliseconds. |
| detect-multiplier multiplier-value | Specifies the local detection multiplier. NOTE:
After BFD is enabled, OSPF establishes BFD sessions only with neighbors in the Full state. |
The value is an integer ranging from 3 to 50. By default, it is 3. |
Usage Guidelines
Usage Scenario
The link failure or the topology change causes devices to re-calculate routes. Therefore, the convergence of routing protocols must be sped up to improve the network performance.
Link faults are unavoidable. Therefore, a feasible solution is required to detect faults faster and notify the faults to routing protocols immediately. If BFD is associated with routing protocols, once a link fault occurs, BFD can speed up the convergence of routing protocols.
Prerequisites
The configured parameters of the BFD session are valid on an interface only when BFD is enabled on the interface.
Procedure
The receive-interval is obtained through the negotiation between the local end and peer end by comparing the values of the local min-rx-interval and the peer min-tx-interval. If the local end fails to receive a BFD packet from the peer end within an interval of receive-interval × multiplier-value, it considers that the neighbor is Down.
Configuration Impact
If global BFD is not enabled, you can enable BFD on an interface but cannot set up BFD sessions. Similarly, if only parameters of a BFD session are set but the ospf bfd enable command is not used, the BFD session cannot be set up.
BFD configured on an interface take precedence over BFD configured in a process. If BFD is enabled on an interface, the BFD parameters on the interface are used to establish BFD sessions.
Precautions
After BFD is enabled, BFD sessions can be created only between the two ends that have set up an OSPF neighbor relationship and the relationship is in the Full state.
The ospf bfd enable command and the ospf bfd block command are mutually exclusive.
After BFD is disabled from an interface through the undo ospf bfd enable command, the parameters for setting up BFD sessions remain on this interface but do not take effect.
