Technical Reports (CIS)

Document Type

Technical Report

Date of this Version

January 2003


University of Pennsylvania Department of Computer and Information Science Technical Report No. MS-CIS-03-27.


Performance of peer-to-peer resource sharing networks depends upon the level of cooperation of the participants. To date, cash-based systems have seemed too complex, while lighter-weight credit mechanisms have not provided strong incentives.

We propose exchange-based mechanisms for providing incentives for cooperation in peer-to-peer file sharing networks. Peers give higher service priority to requests from peers that can provide a simultaneous and symmetric service in return. We generalize this approach to n-way exchanges among rings of peers and present a search algorithm for locating such rings. We have used simulation to analyze the effect of exchanges on performance. Our results show that exchange-based mechanisms can provide strong incentives for sharing, offering significant improvements in service times for sharing users compared to free-riders, without the problems and complexity of cash- or credit-based systems.



Date Posted: 04 August 2005