Snmp-based Network Topology Discovery System And Its Realization

Today's information society depends on computer network so much that the reliability of computer network has become a more crucial issue. As a result, it is very significant to pay attention to network management nowadays. Topology discovery is the basis of network management. By acquiring the information of network topology, network administrators can manage and optimize the network much better. However, because of the dynamic nature and large scale of today's IP networks, keeping track of topology information manually seems an impossible task. The purpose of this thesis is to design new topology discovery and display algorithms and deploy them to implement an accurate and effective topology discovery system.This thesis introduces several common protocols which could be used in topology discovery at first. And these protocols are compared to each other according to their network load, speed, accuracy and suitable application when they are applied to discover the network topology. In addition, this thesis is concerned with summarizing seven topology discovery algorithms, and comparison of the advantages and disadvantages among these algorithms is also presented. There are two key issues for all topology discovery algorithms: alias names of routers and topology display, and several methods exist to solve these questions. However, these solutions have their own weakness. Three improved topology discovery algorithms are proposed in this thesis. First, for the traditional algorithm that utilizes an address table to identify the alias names of routers, this thesis presents a new improved algorithm based on a single and consistent data structure. Not only the time complexity of those two algorithms but also the space complexity is analyzed in the thesis. Second, to avoid the topology equivocal display problem, this thesis presents a new topology display algorithm, named TDASC, based on symmetrical circle. Moreover, DFS-TDASC, a new TDASC algorithm using the idea of depth first search, is also discussed at the same time to resolve the problem when TDASC is applied in the reality.Finally, these three new algorithms consist of a complete topology discovery system, and it has been implemented and tested in the real networks. It is shown that these algorithms are efficient and accurate.