Per-SAP loopback with MAC swap is supported on all 7210 SAS platforms as described in this document, except the 7210 SAS-D.
Per-SAP loopback with MAC swap is is useful for testing the service configuration and measuring performance parameters such as throughput, delay, and jitter on service turn-up. Typically, the testhead OAM tool is used to inject packets at a desired rate into the service from the remote site. It is also possible to use a third-party external test device to inject packets at a desired rate into the service at a central office location. For more information about SAP loopback functionality, see the 7210 SAS-D, Dxp, K 2F1C2T, K 2F6C4T, K 3SFP+ 8C Services Guide.