Reliability evaluation of communication systems using flow graphs

Reliability of a network containing only link failures is well attempted in the reliability literature. In a communication network, node failure probability is sometimes as significant as link failure probability. The problem has been given little attention. The procedure evolved is tedious and the resulting reliability expression is quite lengthy. In this paper, the flow graph method of reliability evaluation has been extended to consider simultaneously the node as well as link failure. The method suggested is simple and leads to a simpler reliability expression. An example has been solved doing all the steps of the procedure clearly.