FTP条件下CSMA/CD协议信道访问公平性研究

Study on CSMA/CD channel access fairness under FTP

在共享式局域网环境下,信道的惟一性与主机接入的随机性构成了一对矛盾,这必然导致从不同主机发送的数据帧在共享信道上发生碰撞,为了降低碰撞所引发冲突的机率,数据链路层采用了CSMA/CD协议,但是该协议能否保证信道分配的公平性是一个鲜有研究的课题。文章结合应用层FTP协议,在NS2仿真环境下搭建实验拓扑并仿真模拟,通过性能分析,证明CSMA/CD可以有效保障信道访问公平性并维持FTP性能。

In shared LAN（Local Area Network）, the unique channel and random access host constitute a contradiction, which results in collision of frames generated from different hosts. In order to reduce the probability of collision, CSMA/CD protocol is used in data link layers. However, whether the protocol can ensure the fairness of channel allocation is a topic barely researched. Network LAN topology is designed under FTP and simulation is executed by using NS2 in this paper. Performance analysis shows that CSMA/CD can effectively protect channel allocation fairness and maintain FTP performance.