Leveraging social networks for increased BitTorrent robustness

In peer-to-peer content delivery systems, such as BitTorrent, there may exist nodes that are non-cooperative and do not contribute their upload bandwidth to the system while still downloading content from others. The current widely used countermeasures against this freeriding behavior have been shown to be ineffective. In this paper, we address the problem by leveraging the trust latent in the social networks and explicitly incorporating the social links as part of the BitTorrent content distribution infrastructure. Our extensive system evaluation produces several insights. First, the social network topology alone without the trackers is an efficient and scalable content distribution medium. Second, thanks to the cooperative social links, BitTorrent's robustness to freeriding significantly improves. Finally, we find that a hybrid solution in which peers download from both their friends and other peers obtained from the trackers has the highest robustness to freeriding, shortest download completion times and the most balanced upload bandwidth utilization.