Research Of Network Performance Measurement

More and more have people's lives been being influenced and changed by Computer Network, especially the Internet. Meanwhile, Networks are more and more complex. Network measurement is the important way by which we can understand networks and make use of them better. Performance measurement is one of important fields in the area. Bandwidth is a kind of valuable network resources, the measurement of bandwidth especially available bandwidth is of significant meaning. So we must search after effective, accurate, practicable measurement methods and tools. Establishing application performance metrics and implementing according measurement tools are also vital for development of various applications, and for monitoring, management of networks.The major contributions of this dissertation are summarized as follows:(1) An available bandwidth measurement tool named DPathload is presented, which can adopt well for the fluctuation of network flows. After systematically analyzing of the art of research of bandwidth measurement, we find the ambiguity of available bandwidth metrics and present a hierarchical method for defining bandwidth metrics. Current available bandwidth measurement tools neglect the property of fluctuation of available bandwidth, and so their results are far away of true. DPathload can make adaptive adjusts to the fluctuation of flows, distinguish and eliminate the effect of "noise" and presents a more precise measurement results.(2) A policy of selecting the length of measurement packets is presented. The reasonable choice can lessen negative effect resulted by measurement load to applications and improve the measurement veracity. But there is very little result about this research area. By simulation experiments and some analyses, we proposed that 800 bytes is the preferred measurement packet length.(3) The performance metrics and measurement tools of five popular applications are proposed. For the purpose of assessing the end-to-end performances of applications, including FTP, HTTP, TELNET, POPS and SMTP, we analyze the characteristics and communication process of every application and present according performance measurement metrics, such as FTP connecting request time and FTP data transmission throughput and so on. Combing with theactive application probing mode presented in the large-scale network performance measurement system NIPMAS, we develop corresponding measurement tools and validate one of them. The results indicate httpprob, HTTP performance measurement tool, can accurately report the true performance of HTTP application. Now these tools are applied in the NIPMAS.