The Research Of Overlay Topology Matching Method

In P2P systems overlay network is a logical network that is built upon physical network and constructed with the connections among peers. In overlay network, each peer maintains the information of adjacent peers and data is transferred by the cooperative peers so that they can provide supports to applications in upper layers. During the construction of overlay network there exists the mismatching problem between the topology of overlay and physical network which is called topology mismatching and the degree of it will have a direct impact on the working efficiency of applications.Through the analyzing the deficiencies of existing approaches for solving topology mismatching in P2P systems, our research work mainly focuses on the overlay matching methods based on the position information of peers. Moreover it includes two parts: 1) present a method about overlay matching based on the relative position of peers; 2) propose a method by using physical position of peers to solve topology mismatching.For the first method, the basic principle is to acquire the route from the joining peer to destination host with fixed IP address, and then utilize the route matching method to judge the relationship of the relative position between two peers. With the relative position of all peers, those peers whose relative position is nearer will be selected out as neighborhood ones so that the topology mismatching problem can be solved efficiently. The experiment indicates the constructed overlay matches well with the physical network.As the second method, the core idea is to deduce the neighborhood relationship among the peers with the assignment blocks of IP address. In order to restrict the area of selecting peers, the concept of Location and Super Location is introduced for constructing the two layers overlay. With these means, the matching degree between overlay network and physical network can be improved. The simulation experiment shows that this method has great advantages in many aspects such like reducing the delay between peers, decreasing the connection adjustment for the new joining peer, etc.In the last part of this paper, we give a brief introduction to the design and implementation of simulation program used in the experiments, besides that, some network models and algorithms used in program are mentioned in the part.