The Research Of HSTCP Congestion Control Algorithm And Its Improvement Strategy

With the development of Internet and the increase of network users,study on network congestion control become more and more important. TCP is a network technique which was born from practice and is making great progress in practice continuously. Nowadays the stability of network is inseparable with the successful TCP congestion control algorithm.TCP Reno,as the standard TCP congestion control algorithm,utilizes AIMD mechanism to adjust its congestion window.However,along with the development of high bandwidth and great delay networks ,regular TCPs do not achieve good performance when running on such networks. Nowadays study on high speed networks develop quickly at home and abroad,there are many algorithms appeared,among them HSTCP algorithm achieves easily and has good scalability, it is also based on AIMD, when current congestion window size is large, HSTCP will increase its congestion window more quickly and decrease it more slowly than TCP Reno does. Whereas its defects constrain its widely applying.HSTCP congestion control algorithms are investigated systematically in this paper after analysing the limitations of TCP Reno applying in high speed network.the performances and imperfect aspects of HSTCP algorithm also have been studied. For the environment of high speed networks,I make some improvement about the latter part of slow start of HSTCP because of its quick increase,the friendliness with regular TCP and RTT fairness are also enhanced. The proHSTCP improves the window increase mode of follow-up slowstart,adds a fairness factor and decides which congestion avoidance algorithm to use according to the condition whether the Channel bottleneck has been completely used. The enhanced HSTCP improves the window increase mode of follow-up slowstart,adds a fairness factor and decides which congestion avoidance algorithm to use according to the condition whether the Channel bottleneck has been completely used. In theory,the modified HSTCP can be more friendly and improve the RTT fairness evidently.Based on the congestion control algorithm in the present dissertation a performance test is carried out. The results obtained show that the algorithm proposed in this paper has good performance.