A New Method for Synchronizing the Time of Networked Computers

本项目旨在设计和测试一种改进计算机网络时间传播的系统。该系统由两部分组成：1)使用拨号电话连接NIST主时间刻度校准时钟的服务器，以及2)通过本地或广域网从服务器请求校准数据的客户端。服务器和客户端构建本地时钟和校准通道的性能模型，并使用这些模型来调整本地时间和校准间隔以保持指定的精度。互联网被用来比较该方法与其他系统的性能。这种方法比现有的网络时间协议更简单，而且可能更准确，因为：1)可以有更多的主服务器，因为它们不需要特殊的硬件。因此，任何客户机和主服务器之间的网络距离都可以很短。2) NIST和每个主服务器之间的通道更容易表征，因为它是稳定的，并且在很大程度上是相互的。其结果是在相同精度水平下减少校准频率，或者在相同校准间隔下提高性能。

This project addresses the design and testing of a system for improving time dissemination on computer networks. The system consists of two parts: 1) servers whose clocks are calibrated using dial-up telephone links to the NIST primary time scale, and 2) clients who request calibration data from the servers via either a local- or wide-area network. The servers and clients construct models of the performance of the local clock and the calibration channel, and use these models to adjust the local time and the interval between calibrations to maintain a specified accuracy. The Internet is being used to compare the performance of the method with other systems. The method is simpler and potentially more accurate than the existing Network TIme Protocol because: 1) there can be many more primary servers since they require no special hardware. The network distance between any client and a primary server therefore can be quite short. 2) The channel between NIST and each primary server is easier to characterize because it is stable and reciprocal to a high degree. The result is either less frequent calibrations for the same level of accuracy or improved performance at the same calibration interval.