The IP address of the node of this Nx_port, as
indicated by the Nx_Port in a GS3 message that it
transmitted. The GS3 format specifies a 32-bit
IPv4 address or a 128-bit IPv6 address. For the
former, the leftmost 96 bits (12 bytes) are set to
x'00 00 00 00 00 00 00 00 00 00 FF FF' and the
rightmost 32 bits are supposed to contain the
IPv4 address.