FDDI stands for Fiber Distributed Data Interface. The FDDI standard is ANSI X3T9.5 . The FDDI topology is ring with two counter rotating rings for reliability with no hubs. Cable type is fiber-optic. Connectors are specialized. The media access method is token passing. Multiple tokens may be used by the system. The maximum length is 100 kilometers. The maximum number of nodes on the network is 500. Speed is 100 Mbps. FDDI is normally used as a backbone to link other networks. A typical FDDI network can include servers, concentrators, and links to other networks. CDDI is a copper version of FDDI which uses category 5 cable. Obviously the distance is more limited than FDDI.