Design And Implementation Of Routing Mechanisms In SDN-based Space Information Network

Due to the extensive coverage,flexible networking and not bound by geography and infrastructure restrictions,etc.,space information network can provide global ubiquitous wireless environment at any time.It can not only provide wireless services for global users,but also be regarded as means of information communication in space scientific exploration.To adapt the increasing demand of multimedia services,how to design efficient diffserv routing mechanisms has attracted more and more attentions.This thesis introduces Software Defined Networking(SDN)into space information network to decrease the load on the satellite,improve routing computation efficiency and reduce the netwok routing cost,etc.At first,this thesis builds the network model and link model based on the goals of constellation design.According to the thought of SDN,the node models of the space information network are designed,including controller node model,intelligent switch node model and dumb switch node model.In addition,to approach to the real simulation of the routing mechanism in space information network,traffic carried on the network is depicted and dynamically simulated from the perspective of the geographical factors,time factors and service types.Moreover,to overcome the dynamics of space information network,this thesis adopts the virtual topology method to generate the topology snapshots.And snapshots merging algorithm is designed to reduce the number of snapshots.At last,considering the service satisfaction and load satisfaction,two routing strategies including amoeboid-based routing strategy and ripple-spreading-based routing strategy are designed based on the diffserv model.According to the satellite trajectory data and the satellite visibility generated by the software of satellite tool kit,this thesis simulates the proposed mechanisms on the platform of visual studio.The results show that,compared with the benchmark mechanisms,the mechanisms proposed in this thesis have lower packet loss rate andservice request failure rate,especially having fewer routing hops when network load is heavy.Therefore,the proposed mechanisms are feasible and effective.