Dht-based P2p Overlay Network Design And Analysis

Peer-to-Peer (P2P) Network is the combination of distributed system and computer network, which functions in Peer-to-Peer mode, and is different from the Client/Server (C/S) paradigm. All peers are free in behaviors, equal in functions and interconnected in links. Thus it can greatly enhance network efficiency, fully utilize network bandwidth and develop the potentiality of each peer.P2P networks are overlay networks built on the bottom physical networks, thus the first problem we should consider is the topology of overlays, which is decisive and fundamental to working performances and design mechanisms of P2P networks. DHT (Distributed Hash Table), routing and location, load balance, self-adaptation, self-organization and fault tolerance are all based on them. Up to now there have appeared tens of kinds of structured P2P networks, such as ring and chordal ring, tree and Plaxton Mesh, torus and hypercube, butterfly, XOR and hybrid.Based on the former works, we design two novel structured P2P networks based on DHT. One is PDHT, which is built on the Pyramid Network (PN (n)). The other is STDC (Spherical Three-Dimensional Chord). In the two models, we give the routing algorithm, join and leave procedures and analysis of the performances. In the same time, we also discuss fault tolerance and analysis of performances.The thesis is divided into five chapters. In chapter 1, we give the basic introduction of the development, concept and taxonomy of P2P networks. Chapter 2 introduces several structured P2P models, including the most classical model in structured P2P:Chord. In chapter 3, we introduce the first model PDHT. It is constant degree P2P architecture. It achieves a time complexity of O(log4(3N+1)-1) per lookup request, while using O(1) neighbors per node, where N is the network size. Theoretic analysis indicates that the probability that more than half of nodes in the system collectively leave or fail is almost zero. In chapter 4, we discuss the second model STDC, which has four advantages compared to Chord:1) it is not easy to be split; 2) it can accommodate more peers; 3) its routing performance is greatly improved, and 4) the possibility of the overlapping ratio of routing paths is smaller. In chapter 5, we propose some problems to be considered in the future.