Reliability of FDDI´s dual homing network architecture

The authors analyze the reliability of two FDDI computer communication network architectures and make comparisons; these structures are a fault-tolerant dual-homing ring of trees and a failsoft ring of trees. They calculate the probability P[h(s,t)] that two arbitrarily positioned terminal stations (s and t) can communicate by deriving closed-form polynomial expressions for P[h(s,t)] in terms of component failure probabilities. The new expression for dual homing permits efficient quantitative reliability comparisons for networks with an arbitrary number of terminal stations, an arbitrary number of concentrator tree root pairs in the counter rotating dual ring, and varying numbers of ports in the concentrators