【作者】 刘庆峰；

【导师】 卢辉斌；

【作者基本信息】 燕山大学 ， 电路与系统， 2004， 硕士

【摘要】 高速计算机通信网络的关键技术之一是异步传输模式（ATM：Asynchronous Transfer Mode）技术。在ATM网络中，信息的拥塞及丢失是影响网络业务服务质量的主要原因。自适应比特率（ABR：Available Bit Rate）业务是唯一一种可采用反馈机制进行流量控制的业务，因此，近年来ABR业务流量的控制和管理问题成为一个研究热点。通信网络是一个庞大的复杂系统，ATM网络拥塞控制的研究对网络的控制和通信均具有重要的理论意义和实用价值。本文正是以此为研究对象，将控制理论概念引入到网络通信中，很好地解决可控流的拥塞控制问题。本文首先介绍了ATM网络的基本原理，ABR业务的反馈机制，以及ABR流量控制机制，分析了现有的ATM网络拥塞控制原理。其次，对现有基于速率的流量控制算法进行了分析，这些算法中大多都能提高活动连接和连接装置的公平性，但是，也给交换机带来更大的复杂性。基于这点，本文提出了一种流量控制算法，并将部分速率计算工作从交换机转移到源端系统中进行。结果表明，该算法能够减少交换机的速率计算工作以及交换复杂性。而且，还降低了交换机在每一时间间隔内为每条链路计算负载因子的难度，从而使网络中的队列长度保持在稳定状态下，进而达到了网络的全局最优性。最后，本文对提出的算法进行了仿真实验。由于本算法引入三个参数，这三个参数的值对本算法进行拥塞控制的效果起到决定性作用，因此，在仿真中，重点对三个参数的取值范围进行仿真，给出了该参数的最优解，同时，在相同的仿真模型中，对ERICA+算法也进行仿真，对仿真结果进行比较，结果表明该算法达到了很好的效果。该方法和算法的提出，对解决ATM网络的拥塞问题提供了理论指导，具有一定理论意义和实践意义。更多还原

【Abstract】 One of future high-speed computer communication network technologies is Asynchronous Transfer Mode(ATM)technology. The loss and congestion of information are main reasons that affect the quality of service in ATM network. Available Bit Rate(ABR)service is the only one type of traffic that can be controlled using the feedback mechanism, so, in the recent, the control and management of ABR service becomes a hot subject. The communication network is a large and hybrid system, the research on congestion control of ATM network has great significance in theory and practice for the control and communications of network. The paper is just based on it and the control theory is used to solve the congestion of controllable flow in communications network.The paper begins with the basic work principle of networks, and the feedback mechanism of ABR, and the flow control mechanism of ABR, and analyses ATM network congestion control principle in existence.Secondly, analyses rate-based flow control arithmetics in existence, most of these arithmetics improve both the fairness among active connections and the link utilization by putting more and more complexity into a switch. In the paper, we propose a flow control arithmetic in which part of rate-calculation work is moved from switches to source-systems. As a result, the proposed arithmetic reduces the rate-calculation effort and switch complexity in the switch. Furthermore, it reduces the difficulty for calculating load factor every measurement interval in switches, as well as more and more stable queue occupancy in the network, thereby it attain the full furthest excellence.In the end, we simulate for the proposed arithmetic. For three parameters put into the proposed arithmetic, they are most important for the congestion control impact of the proposed arithmetic, so in simulation, the emphases puts value scope of three parameters to simulate, and the right value is given. In the same simulation configuration, puts ERICA+ to simulate, and compares<WP=6>simulation result, the result indicates that method attains good purpose. The proposed method and arithmetic affords the theory guidance for the congestion of the ATM network, and have some theory and practice significance.更多还原