Fiber Distributed Data Interface (FDDI) - Tutorial

Fiber Distributed Data Interface (FDDI) is a Local Area Network standard. Thought it is a LAN standard, theoretically it can span up to 200 kilometers. It is developed by the American National Standards Institute (ANSI). Fiber Distributed Data Interface is used as the high-speed backbone technology on ISPs because it supports high bandwidth. Communication through this standard is very secure due to its dual rings structure. Second token ring is for possible backup, in case of the failure of primary ring. If the second ring is also used to carry data, the total speed will increase up to 200 Mbps otherwise the speed is limited to 100Mbps. Now let us check the different versions of this data communication standard.

Different versions of FDDI
  1. FDDI-II

    If you want to transmit video with voice over a network, we can use this standard. FDDI-2, supports the transmission of voice and video information as well as data. This version adds the capability to add circuit-switched service to the network.

  2. FDDI Full Duplex Technology (FFDT)

    It uses the same network infrastructure but can potentially support data rates up to 200 Mbps. That means, this standard can offer the data transfer rate of a normal FDDI network where both token rings are used to transfer data.

Working of FDDI

FDDI uses dual-ring architecture with traffic on each ring flowing in opposite directions. If the data is transferred on ring 1 is on clockwise direction, the second ring sends data on anticlockwise direction. Fiber Distributed Data Interface is treated as highly secure because of its dual ring character. FDDI uses optical fiber as the primary transmission medium, but it also can run over copper cabling.


FDDI is a collection of four separate specifications, each with a specific function. The function of multi specification is to provide high-speed connectivity between upper-layer protocols.

FDDI Specifications

It has four specifications. They are:
  1. Physical Layer Protocol (PHY)

  2. Physical-Medium Dependent (PMD)

  3. Media Access Control (MAC)

  4. Station Management (SMT)

Further Readings
  1. Access Control List

  2. Dynamic Host Configuration Protocol

  3. How to Check Whether NAT is Failed

  4. Difference Between PPPoE Mode and Bridge Mode

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