Unstructured Network Incentives

More and more applications based on Peer-to-Peer protocol spring up on the Internet, their network structures are two main categories:structural networks and unstructured networks, people put more attention to the unstructured Peer-to-Peer (P2P) networks because they are autonomous, unstructured and decentralized. The research object of the paper is the free-riding problem which widely exists in the unstructured P2P networks. On the basis of study on the classical incentive mechanisms proposed in recent years, we find that there is a conflict between the operating mode on which most P2P applications are currently running and the aim of the proposed incentive mechanisms. The proposed incentive mechanisms focus mainly on how to reward cooperative nodes punish the free riders so as to make the entire network be justice and equitable. However, main income of P2P network operator comes from advertisements in the network community, so in order to attract more users to join the network and stay in network for a long time, operators tend to take the attitude of neglecting and tolerance to free-riders.Aiming at the problem, through drawing on the distributed measurement and the Nash equilibrium in game theory, a DAMR(Distributed algorithm Anti-free-rider based on Message Routing) algorithm is proposed in the paper。This algorithm detects and discourage the free-riders distributively。On the basis of the DAMR algorithm, an incentive mechanism is designed by taking the node's network load into account. In order to analyze the characteristics and performance of the incentive mechanism proposed in this paper better, and to analyze the influence of the incentive mechanism to P2P network and operators, an evaluation model is proposed. Making use of this mathematical model, we evaluate the DAMR incentive mechanism and draw the conclusion that the incentive mechanism can make P2P network system to reach and keep a positive equilibrium. At the end of the paper, through the expansion of GnutellaSim software to add the incentive mechanism to NS-2, a platform for simulation is built up. Through making many times of simulation experiments, a series of data are got. By analysis of the data, the correctness and effectiveness of the DAMR-based incentive mechanism are verified. So the conclusion is that the DAMR-based incentive mechanism can make more efficient use of network, promote the nodes in P2P network to collaborate and enjoy services, make P2P networks more attractive in accordance with the interests of P2P network operators. The research in the paper may have some inspiration to the sound development of P2P networks.