The FDDI module implements one of multiple possible Link level/Network
   level modules in the OSI layered architecture model.

   Fiber Distributed Data Interface FDDI is the basis for the second
   generation of network interconnect architecture for Digital.  The FDDI
   module implements one of the multiple possible Link level/Physical level
   modules in the OSI layered architecture model.  The FDDI Physical level
   includes high-speed, 125 megabaud, fiber optic links which may be many
   kilometers in length.  The FDDI Link level provides a high bandwidth,
   100 megabits per second local area network LAN, and uses the ANSI
   standard FDDI Token Ring.

   The hierarchical relationship of the entities that constitute the FDDI
   module:

               FDDI
                 Port
                 Station
                   Link
                   Phy Port

   The FDDI module incorporates the functions and operations defined in the
   ANSI FDDI Token Ring Media Access Control MAC, the ANSI FDDI Token Ring
   Physical Layer Protocol PHY, FDDI Physical Layer Medium Dependent PMD,
   Station Management SMT specifications, parts of the ISO 8802-1 IEEE 802.1
   Addressing, Internetworking and Network Management, and parts of the ISO
   8802-2 IEEE 802.2 Logical Link Control LLC specifications.

   The FDDI entity is the top-level entity in the hierarchy of entities
   belonging to the FDDI module.