Issues On The Network Congestion Control

With the explosive incrase of Internet size, the number of users and the network applications, Internet is suffering more and more loss packets and some performance depravation problems, and network congestion is one of the severe problems.The direct result of the network congestion is the performance decline of the whole network which includes: the packet loss rate increases, the end-to-end delay increases, the network throughput decreases, and the network system may go through congestion collapse. When the network is in the state of congestion collapse, the network throughput will decreases sharply with tiny load increment.There are many reasons that cause network congestion, and the main of which are listed as follows: the lack of buffer capacity, the lack of bandwidth, the low ability of processor, the weakness of the TCP/IP protocol congestion control, the intended attack of some user, the chaos and bifurcation of the network system.In the present Internet, since the network congestion is inevitable, we must take effective and active methods to avoid and control the congestion, try to reduce the possibility of network congestion to the lowest level, attempt to make the network resume its normal work even after the congestion, and the congestion control should ensure the network efficiency. So, the network congestion control is the main way to improve the network performance and reform the service quality. The investigation of the network congestion control is important not only in the theory but also in the application.In recent years, there are many papers that relate to the network congestion control, and the related studies mainly focus on the following fields: the modeling of the network congestion control system, the nonlinear dynamic behaviors of the network congestion control, the improvement of TCP congestion control algorithms, the investigation of active queue management, et al.In this dissertation, some issues in TCP congestion control and active queue management are studied, which are detailed as follows: (1) Four main TCP congestion control algorithms are studied. The four algorithms areTCP-Tahoe, TCP-Reno, TCP-SACK, TCP-Vegas, and their characteristic, meritand defect are analyzed. Some different network topologies are provided, and the...