PCI FDDI Administrator's Guide

PCI FDDI
ANSI FDDI Standards
Chapter 124
ANSI FDDI Standards
Listed below are the four ANSI FDDI standards and how they combine
to form a completely functional fiber optic network.
The physical layer includes two pieces, the Physical Medium
Dependent (PMD) layer that provides the point-to-point
communications between stations in the network, and the Physical
Layer Protocol (PHY) layer that handles synchronization between
higher layer data and control symbols, and the code bit representation
which is transmitted on the medium.
The data link layer includes the Media Access Control (MAC)
standard and the Logical Link Control (LLC) standard. The MAC’s
primary function is the scheduling, routing and delivery of Frames, the
vehicle used to transmit information on and off the ring. In a FDDI
network, information is transmitted sequentially, within frames, as a
stream of encoded symbols from one station to the next. The order of the
symbols within the frames is predetermined by the MAC standard. The
LLC provides a common protocol between the MAC and the network
layer. In addition to FDDI, the LLC standard also applies to IEEE 802.3,
802.4 and 802.5 networks.
The Station Management (SMT) standard is a layer management
entity which interfaces with the other sublayers. It manages connections
with the ringas well as station configurations and the ring configuration.
FDDI Terminology
Table 1-2
Dual Attachment
Concentrator (DAC)
A concentrator that offers two connections to
the FDDI network capable of accommodating
the FDDI dual ring and additional ports for
other concentrators or FDDI stations.
Dual Attachment
Station (DAS)
A FDDI station that offers two connections to
the FDDI dual ring.