The Research Of Incentive Mechanism In Peer-to-Peer File Sharing System

P2P just is Peer-to-Peer, which can be called Peer-to-Peer networks or point to point communication. P2P technology allows users to share much more resources, It achieves the equally relationship between the users based on the P2P network, furthermore, users could simply finish the exchanging and sharing of resources, so it not only achieves effective the resource sharing, but also reduces the pressure of the server. With the good adaptability, scalability, reliability and other characteristics, P2P technology has been played an important role in distributed computing, collaborative work, network data storage and other areas. Although this technology is increasingly mature and gradually improving, it still faces many problems and challenges.Traditional Peer-to-Peer (P2P) networks assume that each user can actively share their own resources, which leads to a lot of free free-riders.Actually, the user's free-rider problem (Free Riding) and the Tragedy of Common is very common, it bring on negative impact on network robustness, availability and life cycle.Therefore, how to design an effective incentive mechanism to inspire network nodes active and selfless contributing their own resources is one of the important issues of P2P research in recent years,In order to solve the above problem, according to the principle of "more contribution, more gain", this paper presents an incentive mechanism model based on the relative contributions of the node at the foundation of all kinds of incentive mechanism. The incentive mechanism model can be divided into two parts:The first part of the incentive mechanism settles the problem of the definition and calculation of the contribution for each node. For how to evaluate the contribution of the node, this paper takes into account two factors, one is the size of uploaded file for each node, just is the node provides the size of the contribution for the whole P2P systems. The other is the size of the file which has been downloaded for each node, just is the node has consumed the number of social welfare.The second part of the incentive mechanism model settles the problem of how to provide different services for each node. In this paper, we present a strategy that allocates bandwidth for each competition node based on resource allocation algorithm. The method provides better service and maximizing using of limited bandwidth. The bigger of the value of contribution to the node can be received corresponding rewarded, the smaller of the value of contribution or free-riders receive little or no services. In addition, the method also takes into account the satisfaction of the node and ensures the fairness of bandwidth allocation. Simulation results show that the incentive mechanism fully exhibits the equity, and it greatly improves the collaboration of the node as well as effective restrains the free-riding behaviors, so the performance of the entire networks is greatly enhanced.