The CFM Linktrace Protocol

The CFM linktrace protocol is used to help verify a path and identify where in a path a connectivity problem exists by indicating that an incompete path between the initiating device and the target device exists. The CFM linktrace protocol is similar to IP traceroute. Linktrace messages (LTM) are sent to either a specified MEP or to an MP MAC address. If you specify a MEP, the specified remote MEP must have already communicated with this MEP and there must be an entry in the MEP database for the remote MEP. The linktrace will fail if the remote MEP is specified and the specified MEP has not yet communicated with this MEP.

You can specify a TTL which sets the maximum number of network hops the LTM will traverse before expiring.

You can specify whether each hop along the linktrace path uses the local filter database exclusively or is allowed to also use the local MIP CCM database to determine reachability to the target.

The LTM shares the same priority as the continuity check message and can not be separately configured. The priority for continuity check messages and LTMs is set using the priority command in MEP configuration mode.

This example shows how to send linktrace messages to MEP 2000 from the myMA1 MEP 1000:

System(rw-config)->cfm md string-name myMD1
System(su-config-cfm-md.1)->ma string-name myMA1
System(su-config-cfm-ma.1)->mep 1000
System(su-config-cfm-mep.1000)->linktrace mep 2000
Linktrace to 00-00-00-10-00-03, Transaction ID 29481
MD Name: abc
MA Name: abc
MEP ID : 1, Interface ge.4.18
=====================================================
Hop  TTL        Source MAC      Next hop MAC    Relay
---- ---- ----------------- ----------------- -------
   1   63 00-1f-45-9e-3e-d1 00-00-00-10-00-00  MIP-DB
   2   62 00-00-00-10-00-00 00-00-00-00-00-00     Hit
System(su-config-cfm-mep.1000)->