The lock instruct and loopback capability for MPLS-TP PWs includes the ability to:
administratively lock a spoke-SDP with MPLS-TP identifiers
divert traffic to and from an external device connected to a SAP
create a data path loopback on the corresponding PW at a downstream S-PE or T-PE that was not originally bound to the spoke-SDP being tested
forward test traffic from an external test generator into an administratively locked PW, while simultaneously blocking the forwarding of user service traffic
MPLS-TP provides the ability to conduct test service throughput for PWs, using lock instruct messages and loopback configuration. To conduct a service throughput test, you can apply an administrative lock at each end of the PW. This creates a test service that contains the SAP connected to the external device. Lock request messaging is not supported. You can also configure a MEP to send a lock instruct message to the far-end MEP. The lock instruct message is carried in a G-ACh on Channel 0x0026. A lock can be applied using the CLI or NMS. The forwarding state of the PW can be either active or standby.
After locking a PW, you can put it into loopback mode (for two-way tests) so the ingress data path in the forward direction is cross-connected to the egress data path in the reverse direction of the PW. This is accomplished by configuring the source MEP to send a loopback request to an intermediate MIP or MEP. A PW loopback is created at the PW level, so everything under the PW label is looped back. This distinguishes a PW loopback from a service loopback, where only the native service packets are looped back. The loopback is also configured through CLI or NMS.
The following MPLS-TP lock instruct and loopback functionality is supported:
An MPLS-TP loopback can be created for an Epipe, Cpipe or Apipe VLL.
Test traffic can be inserted at an Epipe, Cpipe or Apipe VLL endpoint or at an Epipe spoke-sdp termination on a VPLS interface.