On the Cohabitation of Adaptive Search Radius Enabled Peers with Regular eMule Peers

Adaptive search radius (ASR) is a peer selection method that can be used in peer-to-peer (P2P) file sharing applications, such as eMule or BitTorrent, in order to reduce the generated traffic. ASR enabled peers try to exchange file parts with the peers which are topologically closer, instead of swapping parts indiscriminately with peers near and far. Traffic travels fewer hops, resulting in fewer congested links, less traffic through tier-1 ISP´s core links and less traffic exchanged among ISPs. We believe it would be easier for ASR to be accepted if it was presented as an enhancement or modification to current P2P applications, instead of an entirely new application. In this paper we study the use of ASR with the eMule protocol and the impact a progressive migration would have. We found that the introduction of ASR enabled peers reduces the generated traffic but also improves the performance of regular eMule peers, preventing users from adopting ASR. We propose modifications to the original ASR algorithm in order for ASR peers to present superior performance when combined with regular eMule peers, prompting users to migrate willingly. We also propose a migration plan which would enable ASR to be gradually introduced into the eMule population. We support our proposal with simulation studies that showed a 19 to 29% decrease in download time and a 27 to 70% reduction in the traffic carried by tier-1 ISPs.