Work on the Fiber Distributed Data Interface (FDDI) began in 1982 by both standards bodies (ANSI) and vendors (Digital, Control Data, Sperry Rand, and others) out of the need for a higher-speed LAN protocol. In 1990, FDDI became an ANSI X3 standard. It specifies a 100Mbps token-passing (similar in operation to Token Ring) shared transmission medium LAN.

The original FDDI standard specified a passive, counter-rotating dual-ring topology over fiber optic cable. In a dual-ring topology, each end-station is a Dual-Attachment Station (DAS). One ring is the primary, on which data flows in one direction, and it is used for data transmission. The secondary ring is backup. The same data that is transmitted on the primary ring is transmitted on the ...

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