A Model of Link Capacities in ISP´s Router-Level Topology

Modeling the Internet is vital for network researches. Recent measurement studies on the Internet topology show that the degree distribution obeys the power-law distribution. However, only the degree distribution does not determine the performance of network control methods. As previous studies have shown, one of important factors to characterize the performance of network control methods in the Internet is a structure of topologies. However, other characteristics, which are even more important, are link capacities and node processing capacities of the network because these characteristics are particular to communication networks. In this paper, we investigate how to model the link capacity in the router-level topologies. We first reveal that the link capacity distribution of ISP´s backbone network in Japan obeys a power-law with exponent -1.1. To clarify the reason for the link capacity distribution, we evaluate throughput of networks having various kinds of link capacity distributions. Our numerical results show that the network with power-law link capacity distribution can accommodate much more traffic than the network with exponential distributions of link capacities.