A Lightweight Reputation System for Bartering Exchange Based Incentive Mechanisms in Peer-to-Peer Systems

One of the major obstacles to the development of the Peer-to-Peer systems is the free riding problem, which significantly degrades the scalability, fault tolerance and content availability of the systems. Bartering exchange ring based incentive mechanism is one of the most common solutions to this problem. It organizes the users with asymmetric interests in the bartering exchange rings, enforcing the users to contribute while consuming. However, the rational nodes still have the opportunities to gain utility without providing complete services to the others. Moreover the malicious free riders could be fatal to all the bartering exchange rings. This paper proposes a reputation system that allows the users to identify free riders by fully utilizing their local transaction information. The identified free riders are recorded in the nodes´ individual blacklists and thus they will be isolated. The simulated results indicate that by applying the proposed reputation system, the request success rate can be noticeably increased since more rational nodes are forced to become cooperative and the malicious free riders can hardly participate in the bartering exchange rings.