Fiber Distributed Data Interconnect (FDDI)

2009 Mar 07

FDDI networks use fiber instead of wire giving data rate of >=100Mbs. Electrical noise does not interfere with optical and has a much higher potential data rate. FDDI networks use shared token ring technology with self looping ability in case of a break in the ring (e.g. a station that failed). When the network is idle a special reserved packet called a token circulates around the ring from station to station. When a station has a packet to send it waits for the token to arrive, sends one packet (even if it has more then one to send), and then passes the token to the next station. This use of the token guarantees fairness or equal access to the network for all stations.

To recover from errors, FDDI uses dual counter rotating rings connecting to each computer. When a computerdetects that it cannot communicate with the next computer, the interface uses the backup ring to bypass the failure (looping to the reverse ring in its interface).

FDDI Frame (i.e. Packet) Format

2005-2009