Characterization of failures in an IP backbone

We analyze IS-IS routing updates from sprint's IP network to characterize failures that affect IP connectivity. Failures are first classified based on probable causes such as maintenance activities, router-related and optical layer problems. Key temporal and spatial characteristics of each class are analyzed and, when appropriate, parameterized using well-known distributions. Our results indicate that 20% of all failures is due to planned maintenance activities. Of the unplanned failures, almost 30% are shared by multiple links and can be attributed to router-related and optical equipment-related problems, while 70% affect a single link at a time. Our classification of failures according to different causes reveals the nature and extent of failures in today's IP backbones. Furthermore, our characterization of the different classes can be used to develop a probabilistic failure model, which is important for various traffic engineering problems.