论文标题
iHorology：将障碍降低到微秒级别的互联网时间
iHorology: Lowering the Barrier to Microsecond-level Internet Time
论文作者
论文摘要
高精度，同步时钟对于越来越多的互联网应用程序至关重要。标准协议及其关联的服务器基础架构已显示出通常使客户时钟在数十毫秒的顺序上同步。我们解决了高精度互联网计时的主要挑战之一 - 客户端和时间服务器之间对路径不对称的时钟误差的内在贡献，这是微秒级准确性的基本障碍。我们首先利用一项测量研究的结果来量化不对称性及其对时间的影响。然后，我们描述了解决路径不对称问题的三种方法：LBBE，SBBE和K-SBBE，每种都基于时间戳与多个服务器交换，目的是为每个客户端的不对称界定界限。我们通过模拟和论证探索他们的能力和局限性。我们表明，可以实现微秒准确性的目标以及如何实现，并如何实现实质性改进。
High precision, synchronized clocks are essential to a growing number of Internet applications. Standard protocols and their associated server infrastructure have been shown to typically enable client clocks to synchronize on the order of tens of milliseconds. We address one of the key challenges to high precision Internet timekeeping - the intrinsic contribution to clock error of path asymmetry between client and time server, a fundamental barrier to microsecond level accuracy. We first exploit results of a measurement study to quantify asymmetry and its effect on timing. We then describe three approaches to addressing the path asymmetry problem: LBBE, SBBE and K-SBBE, each based on timestamp exchange with multiple servers, with the goal of tightening bounds on asymmetry for each client. We explore their capabilities and limitations through simulation and argument. We show that substantial improvements are possible, and discuss whether, and how, the goal of microsecond accuracy might be attained.
