Associating a BFD Session with an Interface

Configure association between BFD status and interface status to trigger fast route convergence. It can be used only in multicast IP single-hop BFD sessions and link-bundle single-hop BFD sessions.

Usage Scenario

On the network shown in Figure 1, two NetEngine 8000 Fs are directly connected at the network layer but are segmented physically by transmission devices. If the link fails, the NetEngine 8000 Fs take a long time to detect the fault and age the direct route. As a result, the network interruption lasts for a long time.

Figure 1 Link with transmission devices between two ends

To prevent the preceding problem, the NetEngine 8000 F associates the BFD session with the interface. If a fault occurs, BFD detects the fault and the BFD session goes Down. The BFD status change triggers the interface's BFD status to Down, triggering rapid route convergence.

Pre-configuration Tasks

Before associating a BFD session with an interface, complete the following tasks:
  • Enable BFD globally.

  • Create a multicast IP single-hop BFD session or a link-bundle single-hop BFD session.
  • Set up the BFD session and ensure that the BFD session is Up.


  1. Run system-view

    The system view is displayed.

  2. Run bfd session-name

    The BFD session view is displayed.

  3. Run process-interface-status [sub-if] [ reboot-no-impact ]

    The BFD session is associated with the interface to which the BFD session is bound.

    If the process-interface-status command is run, the following situations occur:
    • If a BFD session detects a fault and goes Down, the associated interface status becomes BFD_Down.As a result, the direct route of the interface is deleted from the routing table, but BFD packets can still be sent.
    • Although the process-interface-status command has been run, the BFD status will not be reported to the interface if the BFD status changes while the commit command is being executed. This prevents an incorrect BFD status message (when the BFD session is not established or does not go Up) from causing an incorrect interface status change. After the commit command is run, if the BFD status changes, the interface is notified of the change and sets the BFD status to Down. This implements association between the BFD session status and the interface status.
    • When multiple multicast IP single-hop BFD sessions are bound to the same interface, the process-interface-status command can be configured for only one BFD session. This means that the BFD status of the interface is affected by only one BFD session. Between link-bundle sessions and multicast sessions, and between link-bundle sessions, multiple BFD sessions can be bound to one interface enabled with the process-interface-status command. If·an·interface·is·bound·to·multiple·BFD·sessions,·the·interface·goes·down·as·long·as·one·BFD·session·is·down.·Likewise,·the·interface·goes·up·as·long·as·one·BFD·session·is·up.
    • Before the BFD session status is associated with the interface status, the BFD configurations on two ends must be correct and matched.If the local BFD status is Down, check the remote BFD configurations and ensure that the shutdown command is not run on the remote router.
    • If the networking requires that the BFD status must be synchronized with the interface status, you can run the shutdown and undo shutdown commands to change the status of the BFD session after ensuring the configurations on both routers are correct. After the BFD session is configured with the undo shutdown command, a detection timer is started. Before the timer expires, if the BFD session can go Up after the negotiation, the BFD session reports the Up status to the interface. Otherwise, the link is considered faulty, and the BFD session reports the Down status to the interface after the timer expires.In this manner, the BFD status can keep consistent with the interface status.
    • If the shutdown command is run, the BFD status will not be sent to the interface.
    • If the process-interface-status [ sub-if ] command setting exists in the configuration file, after the router is restarted, the BFD session reports the Down state to the interface so that the interface sets its BFD status to Down. This prevents traffic loss in the situation where the BFD session is Up but the interface is Down during initialization of the router.

  4. Run commit

    The configuration is committed.

Checking the Configuration

Run the following commands to check the configuration.

After completing the configurations, run the display bfd session command. The command output shows that Proc Interface Status is Enable.

Copyright © Huawei Technologies Co., Ltd.
Copyright © Huawei Technologies Co., Ltd.
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