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Q: Networking: ( Answered 4 out of 5 stars,   0 Comments )
Subject: Networking:
Category: Computers
Asked by: belari-ga
List Price: $40.00
Posted: 23 Jan 2004 15:55 PST
Expires: 22 Feb 2004 15:55 PST
Question ID: 299533
what is fiber distributed data interface(FDDI)?who design it?how it
works?what is its advantages and disadvantages?
Subject: Re: Networking:
Answered By: darrel-ga on 23 Jan 2004 16:49 PST
Rated:4 out of 5 stars
Hello belari--

I have carefully researched your questions and have your answers.

To conduct this research, I first conducted a Google search of the
following terms: "what is fiber distributed data interface"

You may view the results of my search online. The link is

The definition of Fiber Distributed Data Interface (FDDI), according
to's glossary is "A concept, defined in ANSI
standards, for an optical-fiber-based token-ring network, featuring
(a) dual counter-rotating logical rings, each with a data transmission
capacity of 100 Mb/s, (b) reliable data transfer, (c) active link
monitoring, (d) station management, and (e) survivability features. 
Note 1: The four standards are (a) ANSI X3T9.5, containing Physical
Media Dependent (PMD) specifications, (b) ANSI X3T9.5, containing the
Physical (PHY) specifications, (c) ANSI X3.139, containing Media
Access Control (MAC) specifications, and (d) ANSI X39.5, containing
the Station Management (SMT) specifications.  Note 2: The data rate of
an FDDI ring may be doubled to 200 Mb/s, with loss of redundancy. 
Note 3: FDDI?2, a second-generation FDDI network standard, is under

You may view this definition online. The link is

Next, you requested information about who the designer of FDDI was. To
conduct this research, I searched the following terms: "fiber
distributed data interface"

You may view my search online. The link is

A white paper at stated that FDDI was created by the
American National Standards Institute in the mid-1980s, "At the time,
high-speed engineering workstations were beginning to tax the
bandwidth of existing local-area networks (LANs) based on Ethernet and
Token Ring."

This paper goes on to answer your next question regarding how it
works. FDDI uses optical fiber to transmit information. It typically
uses either single-mode or multimode light rays. The muiltimode fibers
allow more than one mode of light to pass through the fibers. And they
pass through at varying angles. This limits bandwidth. If a
single-mode fiber is used, only one light ray may pass through the
fiber. Single-mode fibers have advantages in that they are able to
provide a higher performance connectivity and can share information
over a longer distance.

You can read more information about the answers to these two questions
from the same white paper online. The link is

Your final question is regarding the advantages and disadvantages to FDDI.

The advantages to FDDI are:

FDDI supports real-time allocation of network bandwidth. This allows
you to use a wide array of different types of traffic.

FDDI has a dual ring that is fault-tolerant. The benefit here is that
if a station on the ring fails or if the cable becomes damaged, the
dual ring is automaticaly doubled back onto itself into a single ring.
You may view an example of this on Figure 7-4 of the following site:

The FDDI compensates for wiring failures. The stations wrap within
themselves when the wiring fails. You may view a chart regarding this
process online at the same link

Optical bypass switches are used that can help prevent ring
segmentation. The faild stations are eliminated from the ring. See
Figure 7-6.

The disadvantages to FDDI are:

There's a potential for multiple ring failures. As the network grows,
this possibility grows larger and larger. The paper discussed above
also stated, "When two ring failuresoccur, the ring will be wrapped in
both cases, effectively segmenting the ring into two separate
ringsthat cannot communicate with each other. Subsequent failures
cause additional ring segmentation."

The use of fiber optic cables are expensive. This has kept many
companies from deploying FDDI in a widespread manner. Instead, they've
been using copper wire and the similar method of CDDI.

I hope this helps. If you need any further information or any
clarification, please don't hesitate to click the "clarify" button.


belari-ga rated this answer:4 out of 5 stars

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