Specifications

B.2 Station Types
B–4 FDDI Overview
B.2.2 Dual Attachment Stations
Dual Attachment Stations (DAS) attach directly to the dual ring.
B.2.3 Single Attachment Stations
Single Attachment stations connect to the ring via a concentrator, that can be of two
types:
• Dual Attachment Concentrator (DAC) — attaches directly to the dual ring
• Single Attachment Concentrator (SAC) — attaches to the ring through other
concentrators.
B.2.4 Physical Connection
As shown in Figure B–2, all devices, whether they are single attachment stations or
dual attachment stations, connect to each other via a full-duplex connection, called a
physical connection.
Each physical connection comprises two physical links (a single fiber-optic cable per
each physical link):
• Single Attachment Stations and Single Attachment Concentrators connect to a
concentrator, or to another station, via one physical connection.
• Dual Attachment Stations and Dual Attachment Concentrators connect to each
other via two physical connections.