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.