N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 7 - LAN, WAN, VPN, WLAN, MAN, FDDI and Optical MANS                                                      Slide 34 of 45 _________________                                                                                  __________

                                             What is an FDDI ?

                                            FDDI Standard

                                            FDDI Rings

                                            FDDI Specifications

                                            Transmission Speed - 100 M bps

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The Fiber Distributed Data Interface (FDDI) specifies a 100 M bps token-passing, dual ring MAN using fiber optic cable. FDDI protocol can also run over copper cable and is known as Copper-Distributed Data Interface.

FDDI Standard: - The American National Standards Institute developed a specification for the FDDI written by the ANSI Committee X3T9.5 in the mid 1980s.

FDDI Rings: - FDDI uses dual-ring architecture with traffic on each ring flowing in opposite directions. It consists of a primary and a secondary ring. In normal operations the primary ring is used for data transmission, and the secondary ring remains idle. A concentrator allows a facility to connect stations and provide for reconfiguration. It allows the secondary ring to take over the transmission during the failure of the primary ring.

FDDI Specifications: The optical fiber channel operates at 100 M bps with a 1300 nm signal. It uses the baseband transmission method. Up to 1000 nodes can be connected to one optical ring. The maximum distance between adjacent nodes can be 2 km apart and the fiber ring circumference can be 120 kms.