SDN-Based Network Communication Redundancy Add Its Application In TCC Systems

With the rapid development of high-speed railway, the improvement of the train speed, and a sharp increase in network data traffic, the reliability and flexibility that the rail network required are more and more important. However, a distributed protocol has been used in traditional network architecture to control and manage network, but on the demand of stable operation of existing lines it cannot update equipment online. But by using software-defined network, the equipments can be centrally managed and remotely configured. In addition, link aggregation technology can solve the problem of insufficient bandwidth without retrofitting existing equipments. So this thesis proposes a network redundancy scheme based on software defined network, which can unify management and dynamic configuration of network-wide with link aggregation.Firstly, the current situation and development of the railway network have been analyzed. Besides, the idea and development of software-defined network has been introduced. And the link aggregation have been researched on its principle and frame structure. As a result, with the link aggregation, the backup links can improve the reliability of network.Secondly, in the environment of SDN, the experiments with link aggregation has been performed. The switch has sended LACPDU periodically. When a link is three times overtime, its data communication can transfer to another link to improve the link reliability of communication link.At last, the train line control board and train control center have been simulated and designed. The emulation board has been implemented and communicated with PLC on route setting, the action of rail switch, as well as the temporary speed limit orders from the transponder. In addition, the train control center has been designed and simulated on coding track circuit and communicating with others. This program has been tested in semi-physical signal system network platform and the testing result shows that it can really improve the reliability of safety data network of signal system.