08-16-2017, 09:20 PM
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SEMINAR ON Fiber Distributed Data Interface (FDDI)
NAME
REG. NO
BRANCH
CONTENTS
INTRODUCTION
STANDARDS
FDDI TRANSMISSION MEDIA
FDDI SPECIFICATIONS
FDDI STATION -ATTACHMENT TYPE
FDDI FAULT TOLERANCE
FDDI FRAME FORMAT
ADVANTAGES
DISADVANTAGES
CONCLUSION
INTRODUCTION
The Fiber Distributed Data Interface (FDDI) specifies a 100-mbps token-passing ,dual ring LAN using fiber-optic
cable.
It is frequently used as high-speed backbone technology because of it s support for high speed bandwidth and
greater distances than copper.
FDDI Uses Counter-Rotating Primary & Secondary Rings
STANDARDS
FDDI was developed by the American National Standards Institute (ANSI) X3T9.5 standards committee in the mid-
1980s .
After completing the FDDI specification, ANSI submitted FDDI to the International Organization for
Standardization (ISO)
FDDI Transmission Media
FDDI uses optical fiber as the primary transmission medium, but it also can run over copper cabling.
Optical fiber has several advantages over copper media.
FDDI defines two types of optical fiber: single-mode and multimode.
Modal Dispersion and it s advantage.
Comparison between Single-mode and Multimode.
Light Sources Differ for Single-Mode and Multimode Fibers
FDDI Specifications
Media Access Control (MAC)
Physical Layer Protocol (PHY)
Physical-Medium Dependent (PMD)
Station Management (SMT)
FDDI Specifications Map to the OSI Hierarchical Model
FDDI Station-Attachment Types
FDDI defines four types of devices:
Single-attachment station (SAS)
Dual-attachment station (DAS)
Single-attached concentrator (SAC)
Dual-attached concentrator (DAC)
FDDI DAS Ports Attach to the Primary and Secondary Rings
Concentrator Attaches to Both the Primary and Secondary Rings
FDDI Fault Tolerance
Dual Ring :
If a station on the dual ring fails or is powered down, or if the cable is damaged, the dual ring
is automatically wrapped (doubled back onto itself) into a single ring.
Optical Bypass Switch :
This is used both to prevent ring segmentation and to eliminate failed stations from the ring.
Dual Homing :
Ring Recovers from a Station Failure by Wrapping
Ring also Wraps to Withstand a Cable Failure
Optical Bypass Switch Uses Internal Mirrors to Maintain a Network
Dual-Homed Configuration Guarantees Operation
FDDI Frame Format
Preamble
Start delimiter
Frame control
Destination address
Source address
Data
Frame check sequence (FCS)
End delimiter
Frame status
FDDI Frame Is Similar to That of a Token Ring Frame
Advantages
FDDI combines the advantage of token passing on the ring topology with the high speed of the fiber optic
transmission.
Its dual ring topology provides redundancy and fault tolerance. The fiber optic cable is not susceptible to EMI
and noise and is more secure than copper wiring .
It can send data for greater distance between repeaters than Ethernet and traditional token ring.
Disadvantages
As always high speed and reliability come with a price.
FDDI is relatively expensive to implement and its distance limitation is less restrictive than of other LAN
links make it unsuitable for true WAN communication.
Conclusion
FDDI is a good choice for medium sized network MANS and large LAN.
The widespread acceptance of FDDI is due mainly to the dramatic improvement in the price and performance
characteristic of optical fiber.
The FDDI has an extended future with opportunities for lower cost designer alternatives media types, and greater
levels of circuit integration.
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