27th Annual IEEE Conference on Local Computer Networks, 2002. Proceedings. LCN 2002.
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Abstract

The research discussed in this aper builds on the success of the Network Time Protocol (NTP)which has been synchronizing clocks on hosts all across the Internet for many years.With a different end goal (NTP seeks to setup and maintain agreement of UTC time in network-connected systems)we aug- ment NTP methods with hardware to improve the accuracy of synchronization that is ossible within an ethernet subnet by more than three orders of magni- tude. Our approach involves a study of the sources of non- determinism in NTP exchanges and their removal by special hardware aids.The added hardware has a real-time synchronized clock output and a pro- grammable ?event synch ?output that can be used to synchronize attached real-time equipment. The hardware aids allow us to achieve much better synchronization precision (100 nsec)while also facil- itating the convergence to synchronization in a vastly shorter time -- about one minute rather than hours or days as required by NTP.
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