A Survey on Overcoming Free Riding in Peer-to-Peer Networks

Since the first report of free riding on Gnutella in 2000,large amounts of network measurement results show that free riding is prevalent in almost all Peer-to-Peer(P2P) networks,which reduces the robustness,availability and lifetime of P2P networks.Overcoming free riding becomes a hot research issue both in academic and industrial communities.The traffic measurement mechanisms in P2P networks are overviewed,which include active measurement and passive measurement.Some detailed traffic measurement results of Gnutella overlay network are illustrated,which indicate the development of free riding in P2P network in recent 6 years.The modeling of P2P network is introduced,and the impacts to system performance of free riding are discussed.Moreover,the authors focus on the mechanisms avoiding free riding and categorize the proposed approaches into incentive mechanisms,game theoretical approaches,and social network or economic models based methods.Each category is discussed in detail,and some typical work is introduced.Especially,the features of these three categories of solutions are analyzed and compared from the aspect of engineering implementation,which is helpful to both the P2P software developers and academic researchers.Finally,future works about the mechanisms discouraging free riding in P2P networks are outlined.