On fairness, optimal download performance and proportional replication in peer-to-peer networks

Abstract

Each peer in a peer-to-peer network, by definition, is both a consumer and a provider of the service. As a consumer, a peer wants to obtain its objects of interest as quickly as possible. However, as a service provider, the peer wants to serve no more than an equitable portion of the total workload. Our first observation in this paper is that if one satisfies the latter criterion of fairness in workload distribution, then one also minimizes the average download time when the delay at the server is convex in the utilization factor of the server. We had previously observed that controlled flooding search in unstructured networks is optimized when the number of replicas of a file is proportional to the request rate for that file. Here we show that such a replica distribution also ensures fairness in the workload distribution and, at the same time, minimizes the average download time seen by a download request. © IFIP International Federation for Information Processing 2005.