高速网络测量系统时钟同步的研究与分析

在监测网络流量行为中，时钟同步是提供准确的网络测度测量值的前提保证．单向延迟等网络性能测度至少需要毫秒级的同步精度。然而，在高速、大规模、分布式的网络环境下，高速的网络流量影响了系统的时钟响应信号，使得原本是线性模型的相对时钟偏移模型受到影响，这一影响使得即便使用NTP或者GPS，都无法很好地解决时钟同步问题．本文以一个分布式的抽样测量监刚乐境PERME和CERNET地区网主干为依托，详细分析和讨论了高速IP网络中的时钟偏移问题．通过大量真实的实验数据时高速网络中的时钟同步问题进行了研究和分析．同时，对如何解决实验中出现的模型的非线性问题指出了自己的见解．

Clock Synchronization Experiment and Research in High-Speed Network

While monitoring the network traffic behavior, clock synchronization is the guarantee to provide the accurate measurement of network metrics. However, in high-speed, large-scale, distributed network environment, the high-speed traffic hinders the clock single from duly response. As a result, the normal linear model of relative clock offset has been changed, which cause even NTP or GPS cannot resolve the clock synchronization problem. Based on a distributed sample measure and monitor system PERME as well as the backbone of CERNET, clock offset problem in high-speed network has been discussed. Through large number of real experiments, clock synchronization problem has been researched and analyzed. Meanwhile, the paper has given its own opinion of that how to settle the non-linear model problem.