RFC 2019 (rfc2019) - Page 2 of 6


Transmission of IPv6 Packets Over FDDI



Alternative Format: Original Text Document



RFC 2019         Transmission of IPv6 Packets Over FDDI     October 1996


Frame Format

   FDDI provides both synchronous and asynchronous transmission, with
   the latter class further subdivided by the use of restricted and
   unrestricted tokens.  Only asynchronous transmission with
   unrestricted tokens is required for FDDI interoperability.
   Accordingly, IPv6 packets shall be sent in asynchronous frames using
   unrestricted tokens.  The robustness principle dictates that nodes
   should be able to receive synchronous frames and asynchronous frames
   sent using restricted tokens.

   IPv6 packets are transmitted in LLC/SNAP frames, using long-format
   (48 bit) addresses.  The data field contains the IPv6 header and
   payload and is followed by the FDDI Frame Check Sequence, Ending
   Delimiter, and Frame Status symbols.

       +-------+                                               ^
       |  FC   |                                               |
       +-------+-------+-------+-------+-------+-------+       |
       |            Destination FDDI address           |       |
       +-------+-------+-------+-------+-------+-------+      FDDI
       |              Source FDDI address              |     header
       +-------+-------+-------+-------+-------+-------+       |
       | DSAP  | SSAP  |  CTL  |          OUI          |       |
       +-------+-------+-------+-------+-------+-------+       |
       |   Ethertype   |                                       v
       +-------+-------+-------+-------+-------+------+------+
       |            IPv6 header and payload ...              /
       +-------+-------+-------+-------+-------+------+------+

FDDI Header Fields:

FC          The Frame Code must be in the range 50 to 57 hexadecimal,
            inclusive, with the three low order bits indicating the
            frame priority.  The Frame Code should be in the range 51 to
            57 hexadecimal, inclusive, for reasons given in the next
            section.

DSAP, SSAP  Both the DSAP and SSAP fields shall contain the value AA
            hexadecimal, indictating SNAP encapsulation.

CTL         The Control field shall be set to 03 hexadecimal, indicating
            Unnumbered Information.

OUI         The Organizationally Unique Identifier shall be set to
            000000 hexadecimal.





Crawford                    Standards Track