dual attachment station (FDDI) (DAS)

FDDI dual attachment stations (DAS) are distinguished between those with one connection to both rings and one MAC component- Single MAC Dual Attachment Station (SMDAS) - and those with one connection to both rings and two MAC components - Dual MAC Dual Attachment Station (DMDAS).

Station types connected to the FDDI ring

Dual Attachment Stations can be inserted directly into the dual ring. Each station of this type contains two ports, designated A and B. Port A is connected to the incoming fiber of the primary ring and the outgoing fiber of the secondary ring, and port B is the other way around. In contrast to Single Attachment Stations ( SAS) and Single Attachment Concentrators( SAC), the DAS station remains in the ring in the event of ring interruptions.