Understanding the effect of P2P overlay on the AS-level underlay

During the past few years, Peer-to-Peer (P2P) applications have become increasingly popular over the Internet. In these applications, a large number (e.g., millions) of geographically distributed end-systems (or peers) form an overlay to exchange content and share their resources. Several recent studies have observed the network traffic at one or few vantage points and shown that P2P applications significantly contribute to the overall Internet traffic(e.g., [2]). Given the distributed nature of P2P applications, the observed traffic associated with a P2P application across different regions (i.e., ASes) in the Internet depends on several factors including (i) the location of participating peers, (ii) the connectivity among the peers, and (iii) the BGP routing of traffic among ASes in the underlay. Therefore, the observed traffic for a P2P application at a single (or few) vantage point(s) clearly does not represent the extent of its impact across the network. Capturing an accurate view of the global impact of a P2P application requires access to a large number of vantage points that is prohibitively expensive. To our knowledge, none of the previous empirical studies on P2P systems have characterized the global impact of a P2P application on the AS-level underlay.