ATM交换机EPD性能分析

利用ＡＴＭ网络传送ＴＣＰ分组时的一个重要问题是分组中任何一个信元丢失都半导致分组的重传，为解决这一问题，一个方法是发生拥塞时交换机有选择丢弃信元，在有限的存储器容量下，交换机智能化的信元集合源状态与缓存器占用的联合分布，基于这一结果，本文推导出的ＥＰＤ系统的分组丢失率的上界和下界，通过分析比较发现，使用ＥＰＤ的系统，当门限设为缓存器大小时其性能将优于无控制系统。

Performance Evaluation for Early Packet Discard in ATM Switch

A problem in sending TCP traffic over ATM network is that the loss of even one ATM cell will corrupt the whole TCP packet.In order to resolve such a problem,it has been proposed that an ATM switch is used to intelligently discard selective cells when congested.Intelligent discarding policies such as EPD can improve the performance of TCP over ATM network with limited buffer.To analyze its performance,a fluid flow model has been introduced in this paper.The joint distribution of aggregate source state and buffer occupancy is obtained.Based on these results,upper and lower bounds of packet loss probability in an EPD system are derived.The analytical comparison between EPD and oncontrol case has shown that the performance of an EPD system with the threshold set at the buffer size is better than or at least equal to the performance of an uncontrolled system.