TCP在数据包随机延迟网络中的性能分析

摘要

TCP数据包在网络传输中发生错误有两种形式:丢包与延迟,已有的成果大多只对TCP在丢包网络中的性能进行了建模,缺少对TCP在随机延迟网络中的建模问题的研究,为此提出了一个TCP在随机延迟网络中的性能分析模型.首先给出并证明了判断数据包流是否为正序的充要条件；然后利用该条件得出数据包流正序出现的概率；最后根据模型分析了TCP在随机延迟网络中的性能.实验结果表明,所得出的数据包流在发生随机延迟后正序的概率与实验网络基本吻合,所提出的模型与不考虑延迟的模型相比,对TCP最大拥塞窗口均值的预测误差降低了43％,对其网络吞吐量性能的预测误差降低47％.%There are two types of packet transmission errors in network, packet loss and delay. Most of the recent researches only consider modeling TCP in packet lost networks. The problem of modeling TCP throughput in packet random delay networks is studied. A sufficient and necessary condition to identify whether a data packet flow was slightly out-of-order or in-order was proposed and proved. Based on this condition, the probability that a data packet flow was slightly out-of-order or in-order in packet random delay networks was analyzed. Finally, TCP performance in packet random delay networks was evaluated using the performance model. Numerical results indicate that the difference between the probabilities of data packet flow is slightly out-of-order or in-order calculated using the proposed model and those in real networks is tiny. Compared with the existing models which do not consider packet delay, the proposedmodel reduces TCP maximum congestion window evaluation approximately by 43% and reduces TCPthroughput evaluation approximately by 47%.