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FDDI: Advantages and Disadvantages

fddi fiber optic network data transmission token ring

This article explores the benefits and drawbacks of FDDI (Fiber Distributed Data Interface).

What is FDDI? (Introduction)

FDDI stands for Fiber Distributed Data Interface. Here’s a breakdown:

  • It’s essentially a high-performance fiber optic token ring network.
  • Think of it as similar to 802.5 and IBM token rings, but it uses fiber optic cables instead of copper.
  • It can support up to 1000 connections.
  • It covers a total fiber length of up to 200 Km.
  • It boasts a data transmission rate of approximately 100 Mbps.
  • It utilizes multimode optical fiber with the following specifications:
    • Optical source: 1300 nm LED
    • Core diameter: 62.5 micron
    • Cladding diameter: 125 micron
    • Numerical aperture: 0.275
    • Bandwidth: 500 MHz/Km

FDDI

  • The 4B5B line code is used for data encoding.
  • Frame sizes range from 17 to 4500 bytes.
  • FDDI cabling consists of two fiber rings: a primary and a secondary ring. One transmits clockwise, and the other transmits counter-clockwise.
  • FDDI defines two traffic classes: synchronous and asynchronous.

Benefits or Advantages of FDDI

Here are the key advantages of using FDDI:

  • Higher Bandwidth: Offers bandwidth up to 250 Gbps, handling data rates up to 100 Mbps.
  • High Security: Fiber optic links are difficult to eavesdrop on, enhancing security.
  • Durability: Fiber optic cables are less prone to breakage compared to other cable types.
  • Immunity to EMI: Fiber optic cables are not affected by Electromagnetic Interference (EMI).
  • Long-Distance Transmission: Fiber optic cables can transmit signals over greater distances, up to about 200 Kms.
  • Lightweight: Fiber optic cables weigh less than copper wires with similar bandwidth capabilities.
  • Multiple Tokens: FDDI uses multiple tokens to improve network speed.
  • Priority Handling: It’s possible to prioritize workstations connected in the chain. Some stations can be bypassed to provide faster service to others based on requirements.
  • Fault Isolation: FDDI can isolate faulty nodes using wiring concentrators for instantaneous re-routing. Wiring concentrators act as centralized cabling connection devices for workstations.

Drawbacks or Disadvantages of FDDI

Keep these disadvantages in mind when considering FDDI:

  • Complexity: FDDI is complex, demanding a high level of expertise for installation and maintenance.
  • Cost: FDDI is costly due to the expense of fiber optic cables, adapters, and concentrators.