79Configuration procedureTo configure BFD for LSPs:Step Command Remarks1. Enter system view. system-view N/A2. Enable LSP verification andenter the MPLS LSPV view. mpls lspv Not enabled by default3. Configure BFD to detect LSPconnectivity.bfd enable destination-addressmask-length [ nexthopnexthop-address [ discriminatorlocal local-id remote remote-id ] ]Not configured by defaultConfiguring periodic LSP tracertThe periodic LSP tracert function is for locating faults of an LSP periodically. It detects the consistency ofthe forwarding plane and control plane and records detection results into logs. You can check the logsto know whether an LSP has failed.If you configure BFD as well as periodic tracert for an LSP, once the periodic LSP tracert function detectsan LSP fault or inconsistency of the forwarding plane and control plane, the BFD session for the LSP isdeleted and a new BFD session is established according to the control plane.Configuration prerequisites• Enable sending ICMP TTL exceeded messages on the intermediate devices between the sourcedevice and the destination device.• Enable sending ICMP destination unreachable messages on the destination device.• To display MPLS information during the tracert operation, enable support for ICMP extensions onthe source device and the intermediate devices.For more information about ICMP time exceeded messages, ICMP destination unreachable messages,and ICMP extensions for MPLS, see Layer 3—IP Services Configuration Guide.Configuration procedureTo configure the periodic LSP tracert function:Step Command Remarks1. Enter system view. system-view N/A2. Enable LSP verification andenter the MPLS LSPV view. mpls lspv Not enabled by default3. Configure periodic tracert foran LSP to the specified FECdestination.periodic-tracertdestination-address mask-length[ -a source-ip | -exp exp-value | -httl-value | -m wait-time | -t time-out| -u retry-attempt ] *Not configured by default
