Coping with network failures

Abstract

Link and node failures in IP networks pose a challenge for network control algorithms. Routing restoration, which computes new routes that avoid failed links, involves fundamental tradeoffs between efficient use of network resources, complexity of the restoration strategy and disruption to network traffic. In order to achieve a balance between these goals, obtaining routings that provide good performance guarantees under failures is desirable.In this paper, building on previous work that provided performance guarantees under uncertain (and potentially unknown) traffic demands, we develop algorithms for computing optimal restoration paths and a methodology for evaluating the performance guarantees of routing under failures. We then study the performance of route restoration on a diverse collection of ISP networks. Our evaluation uses a competitive analysis type framework, where performance of routing with restoration paths under failures is compared to the best possible performance on the failed network. We conclude that with careful selection of restoration paths one can obtain restoration strategies that retain nearly optimal performance on the failed network while minimizing disruptions to traffic flows that did not traverse the failed parts of the network.