Construction And Optimal Search On Topology Matching Logical Network In Unstructured P2p Systems

Due to high reliability and good maintainability, unstructured P2P system has been widely used in the field of application of file sharing. However, the mechanism of peers randomly choosing logical neighbors without any knowledge about underlying physical topology can cause a serious topology mismatch between the P2P logical network and the physical underlying network. The topology mismatching problem brings great stress in the Internet infrastructure and greatly limits the performance gain from various search techniques. Meanwhile, the flooding search mechanism which is used in most unstructured P2P networks causes large amount of unnecessary traffic and redundant messages.To address these two problems, based on the method in Narada system, this paper presents a method constructing the logical topology matching network by building an overlay minimum spanning tree among each source node and the peers, and further optimizing the neighbor connections that are not on the tree. Meanwhile, an optimization of flooding scheme is proposed:a message is broadcasted by using the standard flooding scheme with a certain TTL hops through the whole network so that the searching scope can be retained, then it is forwarded in the remaining hops by a certain rule according to degree information among nodes. Simulation and performance analysis in this paper show that the constructing method and the optimized search mechanism can efficiently alleviate the mismatching problem and reduces the amount of redundant messages.