【作者】 熊辉；

【导师】 王耀青；

【作者基本信息】 武汉科技大学 ， 计算机应用， 2003， 硕士

【摘要】 近十几年来，计算机网络经历了飞速的发展，但是伴随而来的是日益严重的拥塞。拥塞控制，是保证网络鲁棒性的关键因素，也是各种管理控制机制和应用的基础，同时又牵涉到网络运行的经济性，已经成为了当前网络研究的一个热点问题。 由于拥塞的解决必须考虑具体的网络环境和条件，这就使得研究者们所提出的方法只可能对某种特定网络适用。ATM网络是未来高速网路的发展方向，ABR业务作为ATM网络提供的重要服务，与其相关的拥塞控制技术相当富于挑战性。 传统的拥塞控制方法是基于直接推断的，有很大的随机性和人为因素，控制效果不好，容易产生数据错误和丢失，且不适合于精确分析和进一步改进。本文提出应用控制理论的相关思想处理拥塞控制问题，将控制理论的成熟方法引入到计算机网络研究的领域中来，这不仅是打破传统拥塞控制模式的新思路，而且是将控制理论和其它相关学科结合的大胆尝试。 本文解释了计算机网络拥塞问题的现象及其成因，介绍了几种流行网络中的拥塞控制方法，和ATM网络的有关知识，并综述了目前关于ATM网络ABR业务拥塞控制的研究成果，分析了较为流行的方法的优点和不足。 论文首先针对一个简化了的ATM网络模型进行了建模和分析，并应用经典控制理论中普遍使用的PI调节器设计了一个控制器，实现了拥塞控制算法。然后，详细的讨论了ATM网络ABR业务拥塞控制的建模问题。针对ATM网络特殊的协议标准，重点分析了网络元素、影响拥塞控制的因素，并提出了在进行数学建模时应当遵循的原则和必须考虑的问题。根据讨论结果，论文建立了一个对应普适网络结构的拥塞控制数学模型，并给出了控制和优化的目标。更多还原

【Abstract】 In recent years, there was a rapid progress in the computer network. But with this progress, the congestion happened more frequently and the situation is becoming worse. Congestion control is not only the key factor to ensure the robust of the network, but also the knowledge base of the implement of many management mechanisms and application. Further more, congestion control does deal with the running efficiency of the network. So, it has been a hotspot of the research of the network technology.As it must be the way to consider the particular network environment and condition to resolve the congestion problem, those congestion control schemes, which were brought forward by researchers, could only be adopted with a certain network type. ATM protocol is the main technology in the future high speed network, and the ABR service is a key service that the ATM network provides. In this field, the congestion control of the ABR Service in ATM network is of a very high challenge.With a great random and man-made factor, the traditional congestion ideas are based on the direct conclusions. Those plans have not very good control effect, and are easily to make data error or lose. One cannot analyze those plans precisely, so it is hard to make an enhancement. This paper is to solve the congestion control problem by utilizing the mature knowledge of the control theory. It is a fully new way to treat the problem and is an audacious attempt to unit the control theory and other subject.This paper explained the phenomenon and the cause of the congestion in the computer network. It also introduced the congestion control algorithm in several popular networks and the knowledge of the ATM network. A survey was promoted to show the latest research works of the congestion control of the ABR service in the ATM network. The excellences and shortcomings of some popular schemes were analyzed.This paper modeled and analyzed a simplified ATM network structure, and designed a controller with the PI adjuster, which was often used in the classical control theory. And then, this paper discussed the modeling method of the congestion control of ABR service in ATM network. It mainly analyzed the elements in the network and the factors, which influenced the effect of the congestion control. It also found out some problems and rules, which must be considered during the processing of modeling. According to the result of the discussion, this paper developed a mathematic congestion model corresponding to a common network structure, and a control and optimize object was established for the future work.更多还原