Ethernet CFM can be enabled on each individual path under an Ethernet tunnel. Only down MEPs can be configured on each of them and CCM sessions can be enabled to monitor the liveliness of the path using interval as low as 10 msec. Different CCM intervals can be supported on the primary and secondary paths in an Ethernet tunnel.
MEPs can still be configured under the services independent of the Ethernet Tunnels.
The following rules control the interaction between the MEP defined under the eth-tunnel path and the MEP defined in the service:
The down MEPs configured on the eth-tunnel paths must be lower level than any down.
MEPs configured on the associated SAP. The same applies for Virtual MEPs associated with services such as BVPLS. Checks are provided to prevent the user from configuring anything that violates the above rule. An error message is generated to indicate the mismatch.
Other service MEPs (up direction, down higher levels) are allowed with no restriction.
Any down MEP on the associated SAP transmits only over the active path entity.