Configuring LDP LSP Traceroute

You can trace the route followed by an LDP-signaled LSP. LDP LSP traceroute is based on RFC 4379, Detecting Multi-Protocol Label Switched (MPLS) Data Plane Failures. This feature allows you to periodically trace all paths in a FEC. The FEC topology information is stored in a database accessible from the CLI.

A topology change does not automatically trigger a trace of an LDP LSP. However, you can manually initiate a traceroute. If the traceroute request is for an FEC that is currently in the database, the contents of the database are updated with the results.

The periodic traceroute feature applies to all FECs specified by the oam statement configured at the [edit protocols ldp] hierarchy level. To configure periodic LDP LSP traceroute, include the periodic-traceroute statement:

periodic-traceroute {disable;exp exp-value;fanout fanout-value;frequency minutes;paths number-of-paths;retries retry-attempts;source address;ttl ttl-value;wait seconds;}

You can configure this statement at the following hierarchy levels:

[edit protocols ldp oam]
[edit protocols ldp oam fec address]

The periodic-traceroute statement includes the following options:

exp—Specify the class of service to use when sending probes.
fanout—Specify the maximum number of next hops to search per node.
frequency—Specify the interval between traceroute attempts.
paths—Specify the maximum number of paths to search.
retries—Specify the number of attempts to send a probe to a specific node before giving up.
source—Specify the IPv4 source address to use when sending probes.
ttl—Specify the maximum time-to-live value. Nodes that are beyond this value are not traced.
wait—Specify the wait interval before resending a probe packet.