Setting BFD Parameters on the Egress

Procedure

1. Run system-view

   The system view is displayed.

2. The IP link, LSP, or TE tunnel can be used as the reverse tunnel to inform the ingress of a fault. If there is an LSP or a TE tunnel, use an LSP or the TE tunnel. If no LSP or TE tunnel is available, select an IP link. If the configured reverse tunnel requires BFD, configure a pair of BFD sessions for it. Perform one of the following configurations as needed:

   • For an IP link, run bfd session-name bind peer-ip ip-address [ vpn-instance vpn-name ] [ source-ip ip-address ]

   • For a dynamic LDP LSP, run bfd session-name bind ldp-lsp peer-ip ip-address nexthop ip-address [ interface interface-type interface-number ]

   • For an MPLS TE tunnel, run bfd session-name bind mpls-te interface tunnel interface-number [ te-lsp ]

   The peer-ip ip-address value is the LSR ID of the remote device.

3. Run discriminator local discr-value

   The local discriminator of the BFD session is set.

4. Run discriminator remote discr-value

   The remote discriminator of the BFD session is set.

   

   The local discriminator of a local device and the remote discriminator of a remote device must be the same, and the remote discriminator of the local device and the local discriminator of the remote device must be the same. A discriminator inconsistency causes BFD session establishment failures.

5. (Optional) Run min-tx-interval tx-interval

   The local minimum interval at which BFD packets are sent is set.

   When the reverse tunnel is an IP link, the local parameters cannot be configured.

   Effective local interval at which BFD packets are sent = MAX { Locally configured minimum interval at which BFD packets are sent, Remotely configured minimum interval at which BFD packets are received }

   Effective local interval at which BFD packets are received = MAX { Remotely configured interval at which BFD packets are sent, Locally configured interval at which BFD packets are received }

   Local detection interval = Local interval at which BFD packets are received x Remote BFD detection multiplier

   For example, the locally configured interval at which BFD packets are sent is 200 ms, the interval at which BFD packets are received is 300 ms, and the detection multiplier is 4. The remotely configured interval at which BFD packets are sent is 100 ms, the interval at which BFD packets are received is 600 ms, and the detection multiplier is 5.

   • The effective local interval at which BFD packets are sent is 600 ms (MAX { 200 ms, 600 ms }), the effective local interval at which BFD packets are received is 300 ms (MAX { 100 ms, 300 ms }), and the detection interval is 1500 ms (300 ms x 5).

   • The effective remote interval at which BFD packets are sent is 300 ms (MAX { 100 ms, 300 ms }), the effective remote interval at which BFD packets are received is 600 ms (MAX { 200 ms, 600 ms}), and the detection interval is 2400 ms (600 ms x 4).

6. (Optional) Run min-rx-interval rx-interval

   The local minimum interval at which BFD packets are received is set.

   When the reverse tunnel is an IP link, the local parameters cannot be configured.

7. (Optional) Run detect-multiplier multiplier

   The local BFD detection multiplier is set.

8. (Optional) Run process-pst

   A BFD session is allowed to modify the port state table or link state table.

   If an LSP is used as a reverse tunnel to notify the ingress of a fault, you can run this command to allow the reverse tunnel to switch traffic if the BFD session goes Down. If a single-hop IP link is used as a reverse tunnel, this command can be configured because the process-pst command can only be configured for BFD single-link detection.

9. Run commit

   The configurations are committed.