Abstract
The emergence of peer-to-peer (P2P) applications has posed a threat to the operating cost of Internet Service Providers (ISPs) due to the large amount of inter-ISP traffic generated. The problem stems from the mismatch between the P2P overlay network formed randomly and the underlying physical network. Recently, BitTorrent has attracted enormous users by its convenience of large-scale content distribution and has also become a major challenge for ISPs. Therefore, a great deal of study has been done to enhance the traffic locality in BitTorrent. However, some of them could not be achieved by ISPs alone and need to change the original mechanism of BitTorrent, making these solutions hardly used in practice since the problem is only urgent to ISPs. The most suitable solution for ISPs to deploy is probably cache. Nevertheless, most cache-based solutions only account for a single BitTorrent overlay (torrent) which is unpractical. Thus, this thesis presents a cache-based BitTorrent traffic localization scheme designed for ISPs to ease the volume of inter-ISP traffic generated by BitTorrent and also proposes several resource-efficient policies to allocate the limited resources for multiple torrents. The effectiveness of the proposed B-Proxy was also evaluated through realistic simulation on PlanetLab, where hundreds of BitTorrent clients were executed during the experiment. Simulation results show that more than thirty percent of inter-ISP traffic could be saved in a torrent with a relatively small cache size consumed which is only eighth times that of the original file.