TimeWeaver: Opportunistic One Way Delay Measurement Via NTP
TimeWeaver: Opportunistic One Way Delay Measurement Via NTP
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DOI：
10.1109/itc30.2018.00036
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发表时间：
2018-01
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通讯作者：
Ramakrishnan Durairajan;Sathiya Kumaran Mani;P. Barford;R. Nowak;J. Sommers
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作者：
Ramakrishnan Durairajan;Sathiya Kumaran Mani;P. Barford;R. Nowak;J. Sommers
终端主机之间的单向延迟(OWD)对于Internet应用程序、协议和基于测量的分析具有重要意义。我们描述了一种通过被动测量网络时间协议(NTP)流量来识别OWD的新方法。NTP流量提供了从整个互联网上的主机准确、连续地测量OWD的机会。基于对NTP实施和现场行为的详细检查，我们开发了一个称为TimeWeaver的分析工具，它能够评估从NTP测量的OWD的精确度和准确性。我们将TimeWeaver应用于从位于美国的19台服务器收集的约1TB的NTP流量语料库，并报告主机及其关联的OWD的特征，并将其按精度/精度等级进行分类。为了证明这些测量的有效性，我们应用迭代硬阈值奇异值分解来估计来自层次结构中最高层的任意主机之间丢失的OWD。我们表明，这种方法导致了对丢失的OWD的高精度估计，平均错误率在2%量级以下。
One-way delay (OWD) between end hosts has important implications for Internet applications, protocols, and measurement-based analyses. We describe a new approach for identifying OWDs via passive measurement of Network Time Protocol (NTP) traffic. NTP traffic offers the opportunity to measure OWDs accurately and continuously from hosts throughout the Internet. Based on detailed examination of NTP implementations and in-situ behavior, we develop an analysis tool that we call TimeWeaver, which enables assessment of precision and accuracy of OWD measurements from NTP. We apply TimeWeaver to a ~1TB corpus of NTP traffic collected from 19 servers located in the US and report on the characteristics of hosts and their associated OWDs, which we classify in a precision/accuracy hierarchy. To demonstrate the utility of these measurements, we apply iterative hard-threshold singular value decomposition to estimate the missing OWDs between arbitrary hosts from the highest tier in the hierarchy. We show that this approach results in highly accurate estimates of missing OWDs, with average error rates on the order of less than 2%.