Research On Bundle Protocol Routing Algorithm And Realization Of Simulation Platform

Delay Tolerant Networks(DTN)is featured for that the energy volume and storage capacity of nodes are limited and the links are long-delayed and intermittently connected,which results in that there is no persistent end-to-end path in the network.Thus the TCP/IP protocol designed for traditional terrestrial connected networks cannot be well applied to DTN.Adopting store-custody-forward mechanism to solve the communication problem of DTN,Bundle protocol designed by National Aeronautics and Space Administration(NASA)can guarantee reliable data transmission in DTN.However,the Bundle protocol are still facing many challenges in protocol architectures and routing algorithms.First of all,Bundle protocol does not have the mechanism for dynamic topology discovery and maintenance,and nodes in the network can not perceive unexpected changes from other surrounding nodes.Secondly,Contact Graph Routing(CGR)algorithm in Bundle protocol does not take into account the impact of network load and node available buffer in the calculation of routing,and the routing calculation results are not optimal.Finally,the Qo S routing in Bundle protocol is still an unsolved problem.In view of those challenges of Bundle protocol,this paper takes satellite networks as a typical application scenario example in DTN network,and the contributions are as follows:Firstly,the relationship between network node buffer size,link connection timing and network maximum flow in satellite network is analyzed,and Buffer-limited Time Aggregated Graph(BTAG)is adopted to characterize the link connection timing,the link time-varying capacity and the nodes' remaining buffer capacity.For the problem of high algorithm complexity to solve satellite network maximum flow,the maximum flow routing algorithm based on selecting augmenting path early(MFRSN)is proposed for satellite networks.By selecting the earlier path preferentially,MFRSN algorithm can solve network maximum flow quickly,reduce algorithm complexity and increase network throughput.Simulation results verify that the MFRSN algorithm has a better algorithm performance than the Ford-Fulkerson label algorithm.Secondly,load changes and topology changes can lead to link available time period,link available bandwidth and node available buffer changes.For the problem of the existing Bundle protocol is lack of Qo S guarantee,the minimum delay routing algorithm for satellite networks based on load perception(MDRSN)is proposed.By load perception mechanism,MDRSN algorithm can use the cumulative traffic method to obtain the link available time period,link available bandwidth and node available buffer,and calculate the minimum delay route for satellite networks.Simulation results verify that the MDRSN algorithm has a better performance than the CGR algorithm in end-to-end delay and end-to-end delivery rate.Finally,in this paper the dynamic topology discovery and maintenance mechanism and the end-to-end response mechanism are added to the Bundle protocol,and Bundle protocol simulation platform is designed and realized in the Windows operating system.A simulation test bed based on the low-orbit satellites application scenario is built to verify the routing function,data transmission function and the reliability of Bundle protocol.The performance and adaptability to intermittent connected networks of Bundle protocol are tested.Our work lays the basis for the further application of the Bundle protocol in satellite networks and other DTN networks.