The 7210 SAS supports the MS-PW path trace mode of operation for VCCV trace, as per pseudowire switching, but using FEC129 AII type 2. As in the case of VCCV ping, the SAII:TAII used in the VCCV echo request message sent from the T-PE or S-PE from which the VCCV trace command is executed is specified by the user or derived from the context of the MS-PW.