Research And Simulation Implementation Of Loop Avoiding Technology Based On Link-State Quickly Perception

With the development of computer network communication technology, people's requirement of the quality of communication is higher and higher. However, the survivability of the network faces various threats. How to enhance the survivability of the network in natural disasters or man-made damage became a very important task. Although the survivability of the network can be guaranteed by the fault processing mechanism, the IP layer of the running dynamic routing protocol achieve their own treatment of the fault through the routing protocol convergence, such as the convergence mechanism of the link state routing protocol, such way of fault treatment has some limitations. For example, through the researching on OSPF protocol, we found that there will be some unavailable routes and these routes can not be used during the convergence process. Among all the unavailable routes, there will be some routes that contain a loop, which can be avoided under certain conditions. "Loop avoiding technology based on rapid awareness of link-state" improves the ability of fault treatment of OSPF through avoiding the loop during route convergence process, this technology can also improve the processing capacity of network failure in IP layer and consequently enhance the network survivability. The technology, avoiding loop in route convergence process has a certain theoretical basis, but the general rule and the adaptability of the network environment and the fault scenarios are still to be further researched.The topic of this thesis is based on the adaptive routing strategy control system, we research the loop avoiding technology based on rapid awareness of link state, and implement the system at the simulation platform, at last do simulation experiment at scenes of different types of fault to verify the feasibility and effectiveness of the system.The main contents of this dissertation are listed as follows:1. Analyzed the principles of OSPF protocol, fault handling mechanism and route convergence process.2. Analyzed the existing technology of loop avoiding technology of the route convergence process.3. Understood the adaptive routing control system, the SSFNet simulation platform and the OSPF protocol module.4. Designed a loop avoidance mechanism based on rapid awareness of link state.5. Simulation experiments were carried out in the scenarios of different failure types with or without the mechanism, then a detailed analysis and comparison on the simulation result was introduced.