Study Of Congestion Control On IP Network

With the evolvement of Internet based on TCP/IP, the scale, users and traffics of Internet have experienced an explosive growth since 1990's. The network congestion has become more serious and complex due to the ever-increasing network application types and dynamic network parameters such as active sessions and round trip time. Congestion often results in decline of quality of service(QoS) in terms of transmission delay and throughput, which affects the utilization of network resource like bandwidth and buffers. The congestion control is always a hot spot in the field of network research.Internet primarily relies on end-to-end congestion control of TCP to avoid network congestion. TCP can not satisfy various demands of every application on the complex network. In fact, it will be more effective for detecting and preventing congestion if the routers perform queue management schemes. Congestion control schemes for the routers have been researched widely. Multimedia applications such as video and audio have come forth continuously in recent years. UDP flows are not concordant to TCP flows because UDP flows have no congestion control scheme.Congestion control schemes of IP Networks are researched in two different ways of routers and terminals, and the active queue management schemes are studied thoroughly. The followings are the main contents and innovations of this article.(1) To solve the problems caused by the calculation of average queue length in RED, AQMS_PLR(Active Queue Management Scheme based on Packet-Loss -Ratio) is proposed by useing the packet loss ratio of the network to calculate the arriving packet. And the drop probability are adaptively adjusted. The result of the experiments shows that AQMS_PLR can reduce the packet delay and jitter while keep the drop ratio.(2) To solve BLUE's limitation of the range of RTT and number of links, ABLUE(Adaptive BLUE) is proposed. The result indicates that ABLUE is better than BLUE in some aspects.