+------------------------------------+
                 |      RD (8 octets)                 |
                 +------------------------------------+
                 |  Ethernet Tag ID (4 octets)        |
                 +------------------------------------+
                 |  IP Address Length (1 octet)       |
                 +------------------------------------+
                 |  Originating Router's IP Address   |
                 |        (4 or 16 octets)            |
                 +------------------------------------+