FDDI Cable
There are four cable types which can be used with FDDI.
Multimode Fiber Optic Cable
Fiber optic cable, usually with a core size of 62.5 microns. It allows distances up to 2000 meters (6600 feet).
Singlemode Fiber Optic Cable
Fiber optic cable with a core size of 7 to 11 microns. It allows distances up to 10,000 meters (33,000 feet).
Category 5 UTP
An unshielded copper cable, usually with eight wires. The wires are twisted together in pairs, and the cable is rated at frequencies up to 100 MHz. It allows distances up to 100 meters (330 feet).
IBM Type 1 STP
A heavy, shielded copper cable. It consists of four wires, twisted in to two pairs. Each pair is covered with an individual shield, and an overall shield covers the entire cable. It allows distances up to 100 meters (330 feet).
The variety of cable types allows one to design an FDDI network which takes advantage of the strengths of each type in different parts of the network. For example, in areas where long distances are needed, fiber optic cable is commonly used. For areas where distances are fairly short, less expensive Category 5 cable can be used. This gives a lot of flexibility in designing an FDDI network.
Regardless of cable type, the maximum overall logical ring length of an FDDI network can not exceed 200,000 meters (660,000 feet). It is strongly reccomended to keep the actual ring length below 100,000 meters to allow for situations where the primary ring is “wrapped” around a break. Wrapping basically doubles the length of the ring. Also, there may be no more than 500 nodes on one ring.
For more information, please visit www.sophenol.com or email to sales@sophenol.com.
