Proceedings of the ninth annual ACM-SIAM symposium on Discrete algorithms
IEEE/ACM Transactions on Networking (TON)
Introduction to Algorithms
ACM SIGCOMM Computer Communication Review
Computer Networks: The International Journal of Computer and Telecommunications Networking
IEEE Journal on Selected Areas in Communications
In networks characterized by broad degree distribution, such as the Internet AS graph, node significance is often associated with its degree or with centrality metrics which relate to its reachability and shortest paths passing through it. Such measures do not consider availability of efficient backup of the node and thus often fail to capture its contribution to the functionality and resilience of the network operation. In this paper we suggest the Quality of Backup (QoB) and Alternative Path Centrality (APC) measures as complementary methods which enable analysis of node significance in a manner which considers backup. We examine the theoretical significance of these measures and use them to classify nodes in the Internet AS graph while applying the BGP valley-free routing restrictions. We show that both node degree and node centrality are not necessarily evidence of its significance. In particular, some medium degree nodes with medium centrality measure prove to be crucial for efficient routing in the Internet AS graph.