Characterization of Failures in an Operational IP Backbone Network

TLDR

As the Internet becomes a ubiquitous communication infrastructure, its dependability in the presence of various failures becomes critical. The study analyzes IS‑IS routing updates from the Sprint IP backbone network to characterize failures that affect IP connectivity. Failures are classified by IP‑layer patterns, their probable causes inferred (maintenance, router, optical), and their temporal and spatial characteristics are analyzed and parameterized with standard distributions. The analysis shows that 20 % of failures occur during scheduled maintenance, while 30 % of unplanned failures affect multiple links (mostly router or optical), 70 % affect a single link, and the resulting classification yields a probabilistic failure model useful for realistic scenario generation.

Abstract

As the Internet evolves into a ubiquitous communication infrastructure and supports increasingly important services, its dependability in the presence of various failures becomes critical. In this paper, we analyze IS-IS routing updates from the Sprint IP backbone network to characterize failures that affect IP connectivity. Failures are first classified based on patterns observed at the IP-layer; in some cases, it is possible to further infer their 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 happen during a period of scheduled maintenance activities. Of the unplanned failures, almost 30% are shared by multiple links and are most likely due to router-related and optical equipment-related problems, respectively, while 70% affect a single link at a time. Our classification of failures reveals the nature and extent of failures in the Sprint IP backbone. Furthermore, our characterization of the different classes provides a probabilistic failure model, which can be used to generate realistic failure scenarios, as input to various network design and traffic engineering problems.