jkrey@ISI.EDU (Joyce K. Reynolds) (10/25/89)
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RFC 1128:
Title: Measured Performance of the Network Time
Protocol in the Internet System
Author: D. Mills
Mailbox: Mills@UDEL.EDU
Pages: 20
Characters: 633,742
pathname: RFC:RFC1128.PS
This paper describes a series of experiments involving over 100,000
hosts of the Internet system and located in the U.S., Europe and the
Pacific. The experiments are designed to evaluate the availability,
accuracy and reliability of international standard time distribution
using the DARPA/NSF Internet and the Network Time Protocol (NTP),
which is specified as an Internet Standard in RFC-1119. NTP is
designed specifically for use in a large, diverse internet system
operating at speeds from mundane to lightwave. In NTP a distributed
subnet of time servers operating in a self-organizing, hierarchical,
master-slave configuration exchange precision timestamps in order to
synchronize subnet clocks to each other and national time standards
via wire or radio.
The experiments are designed to locate Internet hosts and gateways
that provide time by one of three time distribution protocols and
evaluate the accuracy of their indications. For those hosts that
support NTP, the experiments determine the distribution of errors and
other statistics over paths spanning major portions of the globe.
Finally, the experiments evaluate the accuracy and reliability of
precision timekeeping using NTP and typical Internet paths involving
DARPA, NSFNET and other agency networks. The experiments demonstrate
that timekeeping accuracy throughout most portions of the Internet can
be ordinarily maintained to within a few tens of milliseconds, even in
cases of failure or disruption of clocks, time servers or networks.
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Joyce K. Reynolds