Reciprocity and Barter in Peer-to-Peer Systems
The 29th Conference on Computer Communications (INFOCOM)
9 Pages Posted: 11 Aug 2010
Date Written: March 15, 2010
Abstract
This work investigates reciprocity in peer-to-peer systems. The scenario is one where users arrive to the network with a set of contents and content demands. Peers exchange contents to satisfy their demands, following either a direct reciprocity principle (I help you and you help me) or indirect reciprocity principle (I help you and someone helps me). First, we prove that any indirect reciprocity schedule of exchanges, in the absence of relays, can be replaced by a direct reciprocity schedule, provided that users (1) are willing to download undemanded content for bartering purposes and (2) use up to twice the bandwidth they would use under indirect reciprocity. Motivated by the fact that, in the absence of relays, the loss of efficiency due to direct reciprocity is at most two, we study various distributed direct reciprocity schemes through simulations, some of them involving a broker to facilitate exchanges.
Keywords: reciprocity, barter, peer-to-peer, graphs, flows
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