Oscar: Small-World Overlay for Realistic Key Distributions

Abstract

The research on P2P systems which support skewed key distributions has rapidly advanced in the recent years. Yet, the assumptions on the skews we are dealing with remained pretty simple: most of the existing literature assumes simple monotonous key distribution skews. However, this is not always the case. For example, Gnutella filename traces show that complex key-distributions rather than monotonous skews occur in practice. We show that one of the seminal P2P systems which support skewed keys - Mercury [7], performs poorly given such complex distributions generated from the trace of Gnutella filenames. We discuss the shortcomings of such state-of-the-art techniques. We present an overlay network Oscar, based on a novel overlay construction mechanism, which does not depend on the key-distribution complexity. We demonstrate through simulations that our technique performs well and significantly surpasses Mercury for such realistic workloads.

The work presented in this paper was (partly) carried out in the framework of the EPFL Center for Global Computing and supported by the Swiss National Funding Agency OFES as part of the European project Evergrow No 001935. The work presented in this paper was supported (in part) by the National Competence Center in Research on Mobile Information and Communication Systems (NCCR-MICS), a center supported by the Swiss National Science Foundation under grant number 5005-67322.