On Mapping the Interconnections in Today's Internet

Internet interconnections are the means by which networks exchange traffic between one another. These interconnections are typically established in facilities that have known geographic locations, and are owned and operated by so-called colocation and interconnection services providers (e.g., Equinix, CoreSite, and EdgeConneX). These previously under-studied colocation facilities and the critical role they play in solving the notoriously difficult problem of obtaining a comprehensive view of the structure and evolution of the interconnections in today's Internet are the focus of this paper. We present mi(2), a new approach for mapping Internet interconnections inside a given colocation facility.(1) We infer the existence of interconnections from localized traceroutes and use the Belief Propagation algorithm on a specially defined Markov Random Field graphical model to geolocate them to a target colocation facility. We evaluate mi(2) by applying it initially to a small set of US-based colocation facilities. In the process, we compare our results against those obtained by two recently developed related techniques and discuss observed discrepancies that derive from how the different techniques determine the ownership of border routers. As part of our validation approach, we also identify drastic changes in today's Internet interconnection ecosystem (e.g., new infrastructures in the form of "cloud exchanges" that offer new types of interconnections called "virtual private interconnections"), and discuss their wide-ranging implications for obtaining an accurate and comprehensive map of the Internet's interconnection fabric.