Exploring and Improving BitTorrent Topologies
BitTorrent, the most popular Peer-To-Peer (P2P) file-sharing protocol, accounts for a significant fraction of the traffic of the Internet. Using a novel technique, the authors measure live BitTorrent swarms on the Internet and confirm the conjecture that overlay networks formed by BitTorrent are not locality aware, i.e., they include many unnecessary long distance connections. Attempts to improve the locality have failed because they require a modification of the existing protocol, or interventions by Internet Service Providers (ISPs). In contrast, they propose a lightweight method that improves the locality of active swarms by 6% by suggesting geographically close peers with the Peer EXchange protocol (PEX), without any modifications to the current system.