Research On Closed Loop Control Mechanism Of Multilevel Network Nodes Based On AQM And Differentiated Service

In recent decades, Internet has come into contact with many aspects of people's life. On the one hand, it greatly promoted the progress and development of the society;on the other hand, computer communication network suffers from congestion problem unavoidably due to uncoordinated resource sharing. How to effectively manage and control the complicated computer network, how to design better control structure and control arithmetic to reduce the congestion problem and transmission time-delay and how to satisfy all kinds of requirements of modern network application have led to the concerns of science domain and become the hot spots of communication study field.In order to solve the congestion and time-delay situation currently lied in computer network, the paper discusses the main characteristics and study targets of various congestion control mechanism in detail, illustrates the modeling principle and process of the network simulation, studies the simulation model based on real object, and gives the basal structure of three layers network simulation model. The closed loop control mechanism of network node based on active queue management (abbr. AQM) arithmetic is proposed through the study of a few kinds of typical AQM arithmetic, such as RED, BLUE, ARED, SRED and so on. In order to improve the multimedia transmission service quality, the paper proposes a kind of new closed loop control mechanism, which associates differentiated service (abbr. DiffServ) with probability drop strategy and BP neural network (NN) PID control. At last, a multilevel network node model is designed and the control mechanism based on multilevel network nodes is proposed according to complicated network structure. In this paper, the control structure figures, math models and control algorithms are given, and online simulation based on OPNET show good performance of three proposed control mechanisms.Supported by open foundation of the Field Bus Technology & Automation the key lab of Beijing, my research focuses on network congestion control of AQM and DiffServ, a large quantity of research is done and some achievement has been attained, and contributes to network long-distance control.