Performance Optimization Of Multipath TCP With Software-Defined Network

The traditional TCP protocol serving single path is one of the most important network protocols in the last 50 years,which plays an important role in the efficient and stable transmission of data network.In recent years,with the rapid development of data services and the increasing requirements of emerging services on transmission rate,it has become a development trend to explore multipath transmission to improve network transmission rate.Due to the limitations of the traditional TCP protocol,many defects have been exposed,such as the inability to provide effective management services for multi-path transmission.For this reason,IETF proposed an MPTCP protocol framework that supports multi-path transmission,allowing a single MPTCP connection to establish subflows for data transmission on multiple paths simultaneously.However,according to the analysis of our experimental results,it is found that the existing MPTCP is limited by the lack of global network information and still has many shortcomings.The load balancing of MPTCP cannot guarantee the fair allocation of resources in the resource pool theory,and it often takes tens of seconds before the subflow throughput converges to a stable level,which is not friendly to medium and short streams.In view of the shortcomings of existing MPTCP,this paper proposes an improved MPTCP protocol optimization scheme,S-MPTCP,on the premise of collecting global network information based on software-defined network.Centering on the key concept of expected throughput,the main contributions of this paper are as follows:1.A new routing algorithm is designed.By constructing and solving the maximum flow problem,the optimal subflow routing is calculated and configured for the newly built MPTCP connection to maximize the utilization of network bandwidth resources;2.The resource allocation algorithm is designed to adjust the expected throughput of the relevant subflows,allocate the bandwidth resources explored in the routing algorithm to each connection in the network in a fair and efficient way,and modify the congestion control module to make the subflow's transmission rate converge to the vicinity of its allocated throughput;3.Designed and implemented the above control system based on the Linux kernel of MPTCP and Floodlight controller,and finally measured and evaluated the performance of the system through experiments.The results of various experiments show that the S-MPTCP designed by us can effectively solve the collision of two subflows in the routing and distribution test,and the throughput of S-MPTCP is improved by about 22%compared with the conventional MPTCP.In the load balancing test,S-MPTCP can make the throughput of MPTCP subflow converge to the desired throughput quickly,and the required convergence time is shortened to one-fifth of that of conventional MPTCP,and the fairness between different connection throughputs is improved obviously.