Study On Congestion Control Of High-speed Network

Congestion, or the buildup of traffic in a certain place of the network exists when the communication network was created. Congestion has a profound effect on the overall performance of the network, and is even capable of making the network paralyzed. Thus, congestion control is an essential subject likely to affect the stable and reliable operation of the network, and is also an important issue to be considered in network design. The purpose of congestion control is to improve the utilization of the network resources and to provide the traffic sources with fair resource allocation. With the convergence of the communication technology and the computer technology, traditional telephone switching has evolved into the present B-ISDN, and is go on to advance towards the trend of high-speed and intelligence. In current high-speed networks, the architectures of communication protocols are becoming increasingly complex, and there is a growing variety of traffic types, whose transmission requirements and statistic characteristics differ from one to another. Consequently, congestion in high-speed networks is becoming increasingly complicated, which will undoubtedly bring new challenges to the congestion control.Based on the description of congestion control measures and their implementation algorithms, as well as the statistic characteristics of the communication traffic in literature at home and abroad, this paper studies the closed-loop control mechanism defined by ATM Forum for ABR service types, followed by an analysis and comparison of the advantages and disadvantages of various control algorithms. It then improves a simple but effective control algorithm for traffic flow. This paper also deals with the setup of models for communication traffic. Finally, on the basis of the nature relation between the self-similarity of the communication traffic flow in high-speed networks and the chaos, this paper proposes a prediction model for network traffic flow.This paper falls into the following 7 sections.1. Concerning about the congestion control measures and their implementation algorithms in high-speed networks. ATM Forum categorizes the congestion control measures into the management approaches to communication traffic in high-speed networks. In the defined Traffic Management Specification Version 4.0ISJ, ATM services are grouped into 5 major categorizes. Different control methods are to be employed for different service types. The Rate-base Feedback Control is used for ABR service types. Among the various methods which have implemented the above feedback mechanism, the first generation method, i.e., the binary method is easy to operate with simple design. Its limitations are it is unstable, a feature able to decrease its effectiveness, and it has poor fairness. The second generation rate method makes a great improvement in stability and fairness, but it makes the design complicated and brings burden to the switch..2. Discussing the queuing theory and the development of its applications. The queuing theory is a major tool for switching systems in performance analysis andsystem design. As the architecture, switching and transmission technologies of communication networks evolve, great changes have taken place in the service input processes service regulations of switches. However, the basic patterns and the performance analysis indexes remain unchanged. Up to date, the queuing theory has been the most often employed analysis tool. As the traffic flow into the network is complicated, simulation experiments have substituted the conventional mathematic analytic analysis. In high-speed networks, the effect of service inputs from self-similarity on the performance of the queuing system is a problem yet to be settled.3.Considering the description of the traffic flow characteristics in high-speed networks. The paper describes the behaviors of self-similarity of the traffic flow in high-speed networks and summarizes the various definitions for self-similarity. The definitions demonstrate, from different aspects, the different characte...