网络性能的分析、评价模型及其软件实现

【作者】 刘树刚；

【导师】 刘培玉；

【作者基本信息】 山东师范大学 ， 管理科学与工程， 2000， 硕士

【摘要】 研究计算机网络的性能对于提高网络的速度、克服网络的瓶颈具有十分重要的意义。对网络的性能进行分析和评价，也是进行网络规划和优化的基础，因为一个真正满足用户需求的网络必须是一个高性能的网络。网络性能的研究，对于网络协议的评价、改善和开发也具有重要的参考价值。 本文首先研究并总结了网络性能的定量描述指标，找出了影响网络性能的主要因素。求出反映定量指标间关系的数学表达式是研究网络性能的目标之一，而概率论、随机过程和排队论是进行网络性能分析的重要数学工具。 本文重点对环形网和总线网的性能进行了详细的分析和评价，并对二者的相对性能作了比较。数学分析法、计算机模拟法和实际测量法是三种基本的分析、评价方法。由于测量法针对一个已经存在的网络，无法对网络的性能进行预测，虽然准确但不适合待建网络的性能研究，所以本文采用的是前两种方法。 对于环形网，首先分析了参数α对网络利用率和延迟的影响，并利用排队论知识给出了多令牌环形网的性能情况；然后针对本文提出的一个单令牌环形同模型，对其性能进行了详细的分析，并给出了模拟的方法、步骤及对模拟结果的评价。 而对于总线网，则分别对纯ALOHA、分槽ALOHA、CSMA和CSMA/CD的吞吐量和延迟进行了分析，重点是CSMA/CD的分析。文中给出了各种情况下吞吐量S与提供的负载G之间的关系表达式，画出了相应的函数曲线，并对它们的性能情况进行了比较。总线网和环形网的相对性能文中也作了比较。 最后，本文的软件实现部分在文中所提性能模型的基础上，模拟了令牌环网和CSMA/CD总线网的运行情况，并验证了性能分析所得结论的正确性，而且从输出数据中找到一定的规律。更多还原

【Abstract】 It is of great significance to study the performance of computer networks in order to raise the network speed and overcome the network bottleneck. The network performance analysis and evaluation is also the basis of network plan and optimization, for a network that fully fills the requirement of its user should be a high performance one. Meanwhile, the research of network performance has important reference value for evaluating, improving and developing network protocols. In this thesis, the performance measures and key factors, which have influence on performance, are studied and summarized. One target to study the network performance is to find out the mathematical expressions between each measure. Probability, Random Process and Queueing Theory are important and useful mathematical tools for network analysis. This thesis mainly analyzes and evaluates the performance of token ring and bus networks, and compares their relative performance as well. Mathematical analysis, computer simulation and spot testing are three basic methods for performance analysis and evaluation. Because spot testing only works well under an existed network environment and is unable to forecast the network performance, it is not appropriate to study the performance of a network to be built. In this thesis the former two methods are adopted. In terms of token ring, the influence of parameter a on network utilization and delay is analyzed first. The performance of multiple token ring is presented in the light of the knowledge of Queueing Theory. Then a performance model is put forward and its performance is analyzed in detail. The simulation method, steps and results are also provided. As to bus network, pure ALOHA, slotted ALOHA, CSMA and CSMA/CD are dealt with. The throughput and delay of above protocols,especially that of CSMAICD are analyzed. The relationship expression between throughput and offered load are given, and correspondent function curves are plotted. Their relative performance is also investigated. The relative performance between bus network and token ring network is also compared in this thesis. The last section of this thesis is software implement. It simulates the token ring and CSMA/CD running based on the performance models given in this thesis. The results can be used to verify the correctness of the conclusions drawn from the analysis. Through the output data, some characteristics can be found, too.更多还原