Design Of Distributed Controller And Reliability Research For Software Defined Space-sky Information Network

With the deep research on the space-sky information network, its technology has been developed rapidly, which plays an increasingly important role in people's scientific, cultural and productional activities,and has become a global research hotspot. However, compared with the terrestrial network, there are some problems such as protocol heterogeneity, time-varying topology, poor link quality and limited resources, which bring the research pressure to the network's scalability,compatibility and reliability. With the development of SDN technology and its advantages, more and more domestic and foreign scholars in the academia and industry have launched the research and application on software defined space-sky information network.Based on the concept of space-sky information network and SDN,this thesis improves an architecture of software defined space-sky information network. Based on the architecture, it focuses on the study of distributed controller system, the multi-layer network routing algorithm,the data and control plane reliability. The main work and innovation of this paper are as follows:By refering SDN technology, this thesis improves an software defined space-sky information network architecture model, in which GEO acts as the control plane, LEO and MEO as the data plane and ground station as the management and application plane. The model enhances the control and management capability of the space-sky information network, and improves the availability, reliability and expansibility of the network.By analyzing the system requirements and functional logic, this thesis focuses on the modular design and research of the distributed controller system in the software defined space-sky information network.The controller implements distributed registration and management capabilities through Zookeeper, and the distributed database stores and maintains global network information views. Through testing, the controller's distributed module is working properly, and has considerable processing power with floodlight in the performance. In order to adapt to the space-sky information network, this thesis designed the routing calculation module of the controller, and improved the MLSR routing algorithm which based on the minimum delay and multiple-layer satellite network. The simulation results show that the improved algorithm's cross-layer average end-to-end delay performance is improved by about 16% compared to MLSR.Aimed at the high dynamic characteristics of space-sky information network, based on the content of OpenFlow and OF-CONFIG standard protocol, this thesis presents the switch migration strategy and controller failover mechanism under the condition of ensuring liveness, security,serializability and small migration delay, to achive that control and data plane can be reliable routing and forwarding without interruption in high-dynamic environment.