In the real world, the computer network is made up of many kinds of different type of networks.Routers make connection between these networks, so they play an important role in the process of computer network building and running. In the large-scale network, OSPF(Open Shortest Path First) is the most popular protocol of the IGP(Interior Gateway Protocol), and it is mainly used to choose routing path dynamically. With the requirements of the network increasing, the credibility of the routers need be prompted imperiously.OSPF considers the bandwidth as the only factor of the link cost when calculating the shortest path tree, which cannot guarantee the reliability and credibility of routers, because it is possible to make the router with low credibility as the next-hop router. This thesis deeply analyzes the principle of operation of the OSPF protocol and combines with the mature technology of the trust value computing model base on the TMS (trust management system).The routers must gain the trust certificate from the TMS before they join the network. The trust certificate is used to exchange the trust value between routers which is used to calculate the shortest path tree and generate the trusted routing table.In addition to bandwidth, the scheme of this thesis regards other parameters as influence factors of trust value, such as time delay, packet loss and so on, which can make routers find the most suitable routing path and create the trusted routing table.On the one hand, routers can be based on neighbor routers'running information and local policies to determine the next-hop router which matches the local policies and has a higher trust value.On the other hand, routers report their subjective trust value to neighbor routers in real time, which can update routing table dynamically and effectively. This thesis makes a complete description of the scheme of the trusted reconstruction of OSPF protocol of internet protocol network from preliminary design to protocol implementation, and it is proved to some extent that the scheme is practicable through making test cases and results analysis. |