+-----------------------------------+
                |       RD (8 octets)               |
                +-----------------------------------+
                |  Ethernet Tag ID (4 octets)       |
                +-----------------------------------+
                | Multicast Source Length (1 octet) |
                +-----------------------------------+
                |  Multicast Source (variable)      |
                +-----------------------------------+
                |  Multicast Group Length (1 octet) |
                +-----------------------------------+
                |  Multicast Group (variable)       |
                +-----------------------------------+
                |Originator's Addr Length (1 octet) |
                +-----------------------------------+
                |Originator's Addr (4 or 16 octets) |
                +-----------------------------------+