Research On Small World Model Of P2P Network And Its Frangibility

As the continuously development of computer networks, P2P technology made great improvement on file sharing and information searching. The P2P systems were composed by a set of equal peer nodes, the peer nodes could communicate straightly without third party. Compared with tradition C/S structure, the P2P structure possessed extraordinary obvious superiority on easy expansibility, data updating, high reliability and good ability of balance network overload, so P2P network is rank in the most influential twenty-one technology of 21 century and one of ten technologies which change the world.This paper mainly probed into small world character of P2P networks. First, in allusion to the fact that Gnutella networks has small world characteristic like as high clustering coefficient and short average path length, the paper studied the small world characteristic of P2P networks, and had designed small world model of P2P networks, particularly introduced the generation process of small world model of P2P networks, and analyzed the clustering coefficient and average path length. Also, compared with Chord networks and Random networks, the small world model of P2P networks had better small world characteristic, and possessed less searching time without reference to dynamic and static state.Then, the paper described Gnutella networks, and tested the node delay, consistence of topology structure and resisting ability of attack, also analyzed the small world model of P2P networks' clustering size, diameter and centricity changes assumed that the networks had suffered random attack, attacks based on degree and attacks based on between's nodes. And compared with Gnutella networks and ER model, the small world model of P2P networks and Gnutella networks were the same that they were robust to random attack, most easily frangible to attacks based on degree and more easily frangible to attacks based on between's nodes. But the ER model was most easily frangible to attacks based on between's nodes and more easily frangible to attacks based on degree.To improve the resistance to attacks based on degree and intermediate nodes in small world model of P2P networks, a model base on endurable probability and entropy of degree distribution was proposed to rank partition model in this paper. The model could improve the resistance to attacks based on degree and intermediate nodes.