Reflections on Ten Years of Network Time Service

摘要

The year 2004 marks the 10th anniversary since the start of U.S. Naval Observatory (USNO) time dissemination on the Internet using the Network Time Protocol (NTP). In 1994, our service was inauspicious: two 50MHz/32MB servers on a 56kb WAN link handling one packet every 17 seconds. Today, three servers in Washington, D.C., process over five thousand packets per second from millions of clients across the U.S. and 63 other nations. At the USNO Alternate Master Clock at Schriever AFB, Colorado, two additional servers provide NTP. Seventeen USNO servers with embedded GPS provide U.S. regional coverage from Alaska to Hawaii, from Washington state to Florida, from southern California to Maine. For the past 6 years, USNO has provided time service on the SIPRNET from Washington, D.C., and Schriever AFB. SIPRNET timing will soon expand with remote SAASM GPS servers. Throughout its history USNO, with the assistance of cooperating agencies, has provided free public time dissemination, from time balls to telegraphic time, wireless broadcasts, telephone time, LORAN, GPS, and Internet time. NTP is lightweight, reliable, accurate, and robust. Freely distributed, it has been ported to numerous devices and operating systems. The architecture of NTP is permanently in evolutionary development and in remote system maintenance.