Fair File Swarming with FOX.
Dave Levin, Rob Sherwood, Bobby Bhattacharjee · 2006
Abstract File swarming is a popular method of coordi-nated download by which peers obtain a le from an under-provisioned server. Critical problems arise within this domain when users act selshly, yet most systems are built with altru-ism assumed. Working under the assumption that all peers are greedy, we introduce the Fair, Optimal eXchange (FOX) protocol. FOX, in addition to effective and robust application of the tit-for-tat incentive mechanism, provides theoretically optimal download times when everyone cooperates. Under our assumption of server and peer capabilities, we develop a strong threat model that provides peers with the incentives to not deviate from the protocol. From a theoretical perspective, we prove FOX’s optimality and incentive properties, even when the network consists only of purely self-interested peers. We also discuss issues in implementing and deploying such a system, and address the cost of ensuring fairness in a domain where efciency is so important. I.