RFC 1103 (rfc1103) - Page 2 of 9

Proposed standard for the transmission of IP datagrams over FDDI Networks

RFC 1103            IP Datagrams over FDDI Networks            June 1989


   toward International Standardization for Media Access Control (MAC)
   [4], Physical Layer Protocol (PHY) [5], Physical Layer Medium
   Dependent (PMD) [6], and Station Management (SMT) [7].  The family of
   FDDI standards corresponds to the IEEE 802 MAC layer standards [8, 9,
   10].

   The remainder of the Data Link Service is provided by the IEEE 802.2
   Logical Link Control (LLC) service [11].  The resulting stack of
   services appears as follows:

           +-------------+
           |   IP/ARP    |
           +-------------+
           |  802.2 LLC  |
           +-------------+
           |  FDDI MAC   |
           +-------------+
           |  FDDI PHY   |
           +-------------+
           |  FDDI PMD   |
           +-------------+

   This memo describes the use of IP and ARP in this environment.  At
   this time, it is not necessary that the use of IP and ARP be
   consistent between FDDI and IEEE 802 networks, but it is the intent
   of this memo not to preclude Data Link Layer interoperability at such
   time as the standards define it.

Packet Format

   IP datagrams and ARP requests and replies sent on FDDI networks must
   be encapsulated within the 802.2 LLC and Sub-Network Access Protocol
   (SNAP) data link layers and the FDDI MAC and physical layers.  The
   SNAP must be used with an Organization Code indicating that the SNAP
   header contains the EtherType code (as listed in Assigned Numbers
   [12]).

   802.2 LLC Type 1 communication (which must be implemented by all
   conforming 802.2 stations) is used exclusively.  All frames must be
   transmitted in standard 802.2 LLC Type 1 Unnumbered Information
   format, with the DSAP and the SSAP fields of the 802.2 header set to
   the assigned global SAP value for SNAP [11].  The 24-bit Organization
   Code in the SNAP must be zero, and the remaining 16 bits are the
   EtherType from Assigned Numbers [12] (IP = 2048, ARP = 2054).







Katz