Research On Satellite Network Routing Method Based On Software-Defined Network

With the development of satellite communication network technology,satellite communication is widely used in military,life,rescue,disaster relief and other aspects.Satellites are classified into two types: geosynchronous satellites and nongeosynchronous satellites according to their altitude.The research on geosynchronous satellites has been carried out earlier and has been widely used.However,due to limited orbital resources,satellite locations are increasingly scarce.Low-Earth orbit satellites,which are non-geosynchronous satellites,are slowly becoming a research hotspot due to their low orbit and small time delay.However,the low-orbit constellation network has the characteristics of limited node load,frequent topology changes,and long communication distance.Common dynamic routing algorithms have problems such as routing failure,severe packet loss,and large transmission delay;while static routing algorithms based on time slicing have poor flexibility and has no ability to deal with emergencies.In large-scale networks,there will be too many fragments,which will affect the performance of the algorithm.The two types of routing algorithms have poor adaptability in satellite networks.Software-defined network is a new type of network architecture.It is different from the traditional network architecture.It departs the control plane and the data plane.The control plane calculates the routing path,and the data plane completes the transmission of the data stream,provides a new idea to solve the routing problem of the satellite network.This paper combines software-defined network and satellite network to solve the problems of traditional satellite network routing.The main research work and innovations of this paper are as follows:First,this article designs a software-defined satellite network architecture.According to the idea of software-defined network,LEO satellite constellation and ground station are used as data plane,ground controller is used as control plane,and geostationary satellite is used as out-of-band communication channel to realize the combination of satellite network and software-defined network.And based on the functions of the controller and data plane node of the software-defined network,combined with the characteristics and requirements of the satellite network,realize the functions suitable for the satellite network.Secondly,based on the software-defined satellite network architecture,this article proposes a satellite network routing preset method.This method utilizes the movement regularity of the satellite network,the controller pre-calculates the routing path according to the change of the network topology,and issues a new routing entry for the relevant satellite node before the satellite’s forwarding path is disconnected.Data packets are forwarded according to the new routing entry.The performance of the routing algorithm is optimized by merging the old and new shortest path trees and setting the calculation observation time.Third,this article proposes a load balancing method to balance the link load based on the route preset method.For the actual scenario of emergency large data business,first calculate the shortest path for large data business,modify the link cost on the shortest path,and reroute calculations to adjust the transmission path of small data business.In this way,the specificity of the shortest path of the large data business is ensured,and the transmission efficiency of the small data business is also guaranteed.Finally,this article uses RYU 4.34 controller and Riverbed Modeler 18.6 simulation software to build a software-defined satellite network simulation platform.In this paper,the routing preset method and load balancing method,as well as the related topology prediction,flow table distribution and other functions are implemented in the RYU controller,and the satellite node supporting the Open Flow protocol is implemented in the simulation software,and the satellite node can move during simulation be based on the imported satellite orbit.Simulation experiments have built multiple scenarios to verify the performance of the method proposed in this paper.The experimental results show that the method in this paper is far superior to the dynamic routing protocol method in terms of delay,packet loss rate,throughput and control overhead,can well support the communication of large-scale constellation systems.