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FDDI Topology
Fiber Distributed Data Interface
FDDI is based on two counter rotating 100-Mbit/sec
token-passing rings. The rings consist of point to
point wiring between nodes which repeat the data as
it is received.
The primary ring is used for data transmission; the secondary is used for data transmission or to back up the primary ring in the event of a link or station failure. FDDI supports a sustained transfer rate of about 80Mbps, a maximum of 1000 connections (500 nodes) and a total distance of 200 kilometers end to end. There is a maximum distance of 2 kilometers between active nodes.
FDDI Station Types
There are two main types of stations, class A which attach
directly to dual rings; or class B which attach to a
station acting as a concentrator.
A concentrator is a specialized workstation that attaches to the ring and has multiple ports that allow attachment of other devices in a physical star configuration. These may be cascaded.
Logical Networks versus Physical Networks
