Schemes for Fault Identi cation inCommunication

| A single fault in a large communication network may result in a large number of fault indications (alarms) which makes the isolation of the primary source of failure a diicult task. The problem becomes worse in cases of multiple faults. In this paper we present an approach for modelling the problem of fault diagnosis. We propose a graph based network model which takes into account the dependencies between the diierent objects in the telecom-munication environment and a novel approach to estimate the domain of an alarm. Based on that model we design an algorithm for fault diagnosis and analyze its performance with respect to the accuracy of the fault hypotheses it provides. We also propose and analyze a fault diagnosis algorithm which is suitable for systems for which an independent failure assumption is valid. Finally, we examine the importance of the information of dependency between objects for the fault diagnosis process.