Inter-Swarm Content Distribution Among Private BitTorrent Networks

Private BitTorrent (PT) is a new trend in Peer-to-Peer file sharing system, which provides high incentives for its users to seed after download by maintaining an upload-to-download ratio in the tracker for each registered community member. From the data we collected from six active PT sites, we discover that the population of both users and contents in any single PT site is much less than the public BitTorrent, and the intersection of content sets in different PTs is quite small. Based on this observation, we propose a content sharing/distribution framework among PTs (named CrossPT), as well as its sharing mechanism. In addition, we investigate the sharing strategy of the PT participants in CrossPT using game theory and the fetch strategy by modeling the scenario to a Neighbor Selection Problem (NSP). We prove NSP to be NP-complete and propose a heuristic algorithm to solve it. The evaluations with the input of crawled data from six PT sites demonstrate the efficiency of our mechanism. The content sizes of the six PT sites can be increased by 113.95%-438.46% with CrossPT. Also, the content distribution process can be done in less than one second, excluding the delivery time of the content itself.