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.