Techniques disclosed herein include systems and methods for improving multicast traffic operations in a Shortest Path Bridging (SPB) network by conveying bridging domain information of an incoming interface (IIF) when transporting multicast traffic over the SPB network. Techniques disclosed herein include modifying encapsulation packet header information of existing Mac-In-Mac fields to convey additional information that can be interpreted at edge nodes by modifying edge node interpretation of multicast data. Specifically, the value of the I-SID in the BMAC-DA field can be set to be different from the I-SID value in the I-TAG field. Carrying the L2 VSN I-SID value in the I-TAG allows the Egress BEBs to determine which VLAN/L2 VSN/Bridging-Domain of the IIF is in use, and then modify or preserve underlying header information accordingly.