Structured P2p Networks, Anti-churn Strategy

In recent years, peer-to-peer networks gradually become one important application for Internet. Structured P2P network are the important points in the present study. The structured P2P network based on distributed hash table uses DHT for the resource location. It hashes each resource node in the network a value to the same space, while each sharing resource is posted on the identifier closest node. While the location mechanism solves the problem effectively that the unstructured peer-to-peer network brings in flood mechanism, it brings other questions inevitably. The churn problem in the P2P network is one of the basic questions which we must face among them. In the search process of structured P2P systems, the Churn-Resistant ability is one of the key performance indicators.At present, the study of structured P2P networks mainly concentrates on the direct improvement on the existing DHT agreement. This method has many shortcomings, such as pertinence of an improved strategy which is only suitable for an agreement; incompatibility that improved strategy can only improve some performance value while reducing other performances of the network. But almost each structured P2P network has its own set of network protocol; it is difficult to uniform standards. Therefore, Churn-resistance studies must be specific to a certain DHT agreement.Based on the producing mechanism of Churn problems, this paper systematically summarizes the existing literature of Churn. We make full advantage of the neighborhood between two nodes to construct the expansion topology of Chord network. The Simulation results show that the modified network can provide effective supports for more rapid convergence as well as reducing the network maintenance time with the searching efficiency of O(log N).We present a kind of Churn-Resilience strategy, which is independent with DHT layer and only applied routing layer of the system. In other words, it does not depend on a special routing algorithm and can work with various algorithms. This paper is applied to the strategy in Kelips Chord. The Simulation results show that the strategy can improve the topology coherence in DHT layer, reduce the network maintenance cost in the network environment under Churn and improve Churn-Resistant ability of the system effectively.