FDDI Address Conventions

FDDI information frames are based on Token Ring information frames. As is the case for a Token Ring frame, the information in an FDDI frame is sent with the most significant bit first. And, like Token Ring, the MAC addresses in an FDDI MAC header are expressed in reverse order.

Unfortunately, MAC addresses embedded in an FDDI information field sometimes appear in non-canonical format (bit-reversed, like Token Ring) and sometimes appear in canonical format (not bit-reversed).

  • When the FDDI ring interconnects with Token Ring LANs, the non-canonical (bit-reversed) format is used.

  • When the FDDI ring interconnects with Ethernet LANs, the canonical format is used.

If both Ethernet and Token Ring LANs are connected to an FDDI ...

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