Research And Application Of Network Topology Discovery Technology

Network topology is an important means and tool for network management, and is the basis of other management functions. But it's a very tedious and impossible task to get the topology of a large and heterogeneous network by manual method, therefore topology discovery become a hot issue of network management.Firstly by analyzing the specific process and all the performance indicators of topology discovery, the paper gets a performance evaluation model which can improve the efficiency of research and the performance of topology discovery method. According to the model the paper then analyzes the methods of equipment discovery and type distinguishing to make them better.Secondly the paper analyzes and compares the advantages and disadvantages of various kinds of link layer topology discovery. Due to the topology discovery methods for single subnet can't be used for multi-subnet switched domain and the existing methods for multi-subnet switched domain still have many defects, the paper proposes a new method. The method uses the whole concept as the guidline, separates the network to some switch domains. In each switch domain it firstly establishes the connections between switchers in the critical region and then uses the leaf node method to complete the topology. The method is accurate and applicable, furthermore it doesn't require complete address forwarding table.Thirdly the paper proposes a method based on three layer switching and VLAN technology due to three layer switchers and VLAN technology are more and more extensively used on campus network and enterprise network. The method first groups all the VLANs, after this process a port of a three layer switcher only appears in one VLAN group. Though each VLAN group may has equipments that belong to multiple subnets, a VLAN group can be abstracted to a special single subnet, so it can discovery the topology of a VLAN group by reforming the method for single subnet.Finally the visualization and storage technology of topology are initially studied. A network management system is designed and developed, of which the topology discovery module realizes the methods of the paper. The topology discovery module obtained accurate topology of campus network when it is tested, and the result shows that verifies the correct of the paper's methods.