The token-passing access method for Fiber Distributed Data Interface (FDDI) networking. FDDI uses a ring topology and uses token passing for placing frames on the ring.
The token-passing method used by FDDI is generally similar to the token-passing definition outlined in the IEEE 802.5 specification for token ring networks. However, in an FDDI ring, each host holds the token for a predetermined amount of time and can transmit as many frames as it can produce during this time. When the time interval expires, the host must release the token for the next host on the ring to use. This differs from the IEEE 802.5 specification in that many frames from each host can exist on the ring at the same time, instead of only one frame per host, as is the case in token ring networks. This allows FDDI networks to support higher data traffic rates than token ring networks and makes FDDI more suitable for network backbones.