Research And Improvement Of Chord Model

With the P2P (Peer-to-Peer) technology widely used in Internet application, P2P technology is attracting more and more attention. Recently, the structured P2P network based on DHT (Distributed Hash Table) has become research focus. As a classical structured P2P network, Chord model proposed by MIT has many advantages such as decentralization, Scalability, Load balance. However, due to the heterogeneity of nodes, so much churn caused by dynamic nodes and the limited efficiency of the query, Chord model is not widely used in practice.In order to deal with these problems, a HTC-Chord (Topic-Cluster and Hierarchic Layer Based Chord Model) is proposed in this paper. Compared with original Chord model, two core concepts are integrated into the system architecture:topic-cluster and hierarchic layer, changing chord into a two-dimensional structure with upper and lower levels. In the model, the nodes are divided into different clusters according their interests, which are organized into lower chord network. At the same time, as the represent of the cluster the nodes with the best performance in the cluster composed of the upper chord network. Most queries and dynamic adjustment will occur within the lower chord network, which reduce the cost of query and the churn aroused by the adding and department of the nodes. And the inter-cluster queries are resolved by the upper chord network consist of high-performance nodes, which makes full use of the nodes.After introducing the architecture and the implementation of HTC-Chord in detail, the query efficiency and stability of the two models are compared through Theoretical analysis and simulation and the result of two ways also shows that HTC-Chord has better performance.