Study On Resource Search Algorithms In Structured Peer-to-Peer (P2P) Networks

Recently, P2P(Peer-to-Peer) technology has witnessed a rapid development and has a tremendous impact on people's lives. Basically, how to efficiently query and locate resources is the key to P2P applications, Therefore, P2P resource search algorithms attract a great deal of research attention.This thesis firstly introduces the basic characteristics of P2P networks, benefits and state-of-the-art of research. Specifically, three typical P2P network construction methods are briefly overviewed: hybrid, unstructured and structured P2P. Due to the fact that structured P2P is a relatively efficient way to locate resources, the thesis conducted two improvements to increase the search efficiency in chord algorithm. In detail, the contributions are two fold:(1) First, considering the shortcomings in original Chord: routing information is not abundant, and resource location can only be enforced in one-way, a new algorithm called AB-Chord is designed to reconstruct the routing table in Chord, in which some valid information for efficient routing is appended, and counter-clockwise items also added to achieve two-way resource queries. In additional-Chord implements a new operation to remove the redundant information, so it can reduce the maintenance costs of the routing table. The simulation results show that the AB-Chord is superior to the Chord and Bi-Chord in two aspects of the average query path length and the aver age query delay .That is, AB-Chord's query efficiency has been improved to some extent.(2) Due to the proposed AB-Chord algorithm enlarged the routing table which may cause the forward-storm of query messages, the thesis proposes a new routing table update mechanism for AB-Chord. The new algorithm appropriately extends the periodic time of updating the routing table and makes the joining and leaving the nodes actively send updating messages of the routing table to reduce the number of messages forwarded in the network. Through the simulation analysis, we found new algorithm has improved in three aspects of the overall bandwidth, the input bandwidth, the output bandwidth and it reduced the network bandwidth consumption.