Port loopback with MAC swap is only supported on the 7210 SAS-D.
7210 SAS devices support port loopback for Ethernet ports. There are two types of port loopback commands: port loopback without MAC swap and port loopback with MAC swap. Both these commands are helpful for testing the service configuration and measuring performance parameters such as throughput, delay, and jitter on service turn-up. Typically, a third-party external test device is used to inject packets at desired rate into the service at a central office location. For more information about port loop back functionality, see the 7210 SAS-D, Dxp, K 2F1C2T, K 2F6C4T, K 3SFP+ 8C Interface Configuration Guide.