An Enhanced Performance Of TCP Vegas Based On High Bandwidth Delay Product Network

• Main Authors: Lo Shen-Huei, 羅勝暉
• Other Authors: Chu Yen-Ping
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/07751466039354490371

碩士 === 東海大學 === 資訊工程學系 === 100 === With the evolution of network technology, the network bandwidth and packet transmission distance have been greatly increased. The network environment has gradually evolved into high bandwidth-delay product environment. Low bandwidth TCP protocol has been unable to support the current network environment in high-bandwidth delay product network environment. Therefore, how to enhance TCP transmission performance with high bandwidth-delay product network environment has become a research focus now. Although TCP Vegas has better performance in stability, bandwidth utilization and throughput, it has the problems of early leaving in slow-start phase and slow adjusting speed in congestion window in high-bandwidth delay product network environment. This phenomenon will severely reduce the throughput of TCP Vegas and its ability of grasping network bandwidth. In this paper, we proposed a new enhanced mechanism based on TCP Vegas, High Bandwidth-Delay Product Vegas（HBDP Vegas）. HBDP Vegas assessed the degree of congestion by the ratio of round-trip time and minimum round-trip time. In slow-start phase, HBDP Vegas modified the growth of behaviors of congestion window to enhance the ability of grasping network bandwidth. In congestion avoidance phase, HBDP Vegas dynamically adjusted the value of α and β of TCP Vegas and modified the control method of congestion window to strengthen the ability of adapting to the fast change of network environments. In conclusion, simulation results showed that in slow-start phase, convergence time, competitive situation with other connections and fairness index, HBDP Vegas effectively improved the ability of grasping bandwidth, the response speed of adapting to the change of network environments, and the throughput.