An Analysis of the Congestion Effects of Link Failures in Wide Area Networks

Here we present the results of a study t o deter-mine the effects of link failures on network perfor-mance. The network studied is a virtual circuit based packet switched wide area network. A generic queueing framework is developed t o study the effect of failures, and the subsequent t raf ic restoration, on network per-formance. In general, the congestion resulting after a failure is a transient phenomenon. Hence a numeri-cal methods based nonstationary queueing analysis i s conducted in order t o quantify the effects of failures in terms of the transient behavior of queue lengths and packet loss probabilities. A bounding relationship is developed whereby a network node can determine whether or not congestion will occur as the result of t raf ic restoration after a failure.