Research Of Search Algorithm Based On Unstructured Peer-to-Peer Systems

As we enter the twenty-first century, the development of P2P (Peer to Peer) technology is very rapid, a lot of new P2P applications emerge, it has changed the traditional C/S (Client/Server) mode. In P2P systems, the status of all peers is equal, it weakens or even cancels the central server. Thus, it presents a new challenge to locate resources. How to locate resources quickly and efficiently becomes a focus of P2P research.Compared with structured P2P systems, peers are heterogeneous and dynamic in unstructured P2P system, topology is arbitrary, the traditional search algorithms lead to a large number of redundant routing messages, the efficiency of search algorithms is low. So it is very important to propose an efficient algorithm based on unstructured P2P system.In this paper, a lot of researches have been done on the existing search algorithms in unstructured P2P systems. For the shortcomings of SmartSearch algorithm, we apply One-hop Replication Mechanism in the random graph network. A new search algorithm based on classified peer links in unstructured Peer to Peer systems(referred to as CPLA)is proposed. By using two different values of TTL(Time To Live) and considering the underlying physical network.the search process is divided into two phases.It adopts different search algorithms in different search steps. CPLA aims to ensure the peer coverage and reduce the redundant routing messages.Based on CPLA, we consider a new parameter which is defined as the nearer neighbors density of a peer, the paper also proposes a new search algorithm based on peers'neighbor density in unstructured Peer to Peer systems(referred to as PNDA). PNDA can control the search range further in the local. PNDA aims to reduce the redundant routing messages and response time.Finally, by comparing with the SmartSearch algorithm, the experiments choose three parameters which are peer coverage, average search hops and traffic overheads. The results of experiments show that CPLA and PNDA have higher rate of peer coverage under the same time, the average search hops of CPLA and PNDA are smaller. When the peer coverage is the same, the traffic overheads of CPLA and PNDA are lower.