用可靠性多項式計算網絡全終端可靠度是評估網絡拓撲結構穩定程度的重要依據，精確計算可靠性多項式是一個NP-hard問題。本文通過對基于產生孤立點的概率隨機事件的定義，運用概率不等式變換，給出了點可靠、邊以不同的概率相互獨立失效時，網絡全終端可靠度的上界表達式，在可靠度近似計算過程中避免了對網絡邊割集和路集的搜索。最后，在網絡鏈路壽命服從指數分布時分析了某SDH傳輸網絡的全終端可靠性及其近似計算，以說明本文的方法。

　　Abstract:

　　Computing the all-terminal reliability of communication networks by using reliability polynomial is the important basis to evaluate the stability degree of network topology structure，and computing some coefficients exactly is NP-hard.In this paper，we give the upper bound expression on all-terminal reliability in precondition that probability of edges failure in network are all unequal by the definition of probability Random Events that can bring independent vertices and conversion of probability inequality，and sequentially avoid the searching of cut sets and path sets of network in approximate calculation.Finally， when the edge life is exponentially distributed，the paper analyses and computes the bounds of all-terminal reliability of a SDH network to demonstrate the method.