5 Network Time Protocol (NTP)
NTP is a common method for the synchronization of hardware clocks in local and global networks. The basic
concept, version 1 [Mills88], was published in 1988 as RFC (Request For Comments). Experiences acquired
from its practical use on the Internet was followed by version 2 [Mills89]. The NTP software package is an
implementation of the actual version 3 [Mills90], based on the specification RFC-1305 from 1990 (directory
doc/NOTES). Permission to use, copy, modify and distribute this software for any purpose and without fee is
hereby granted (read File COPYRIGHT).
NTP operates in a way that is basically different from that of most other timing protocols. NTP does not
synchronize all connected clocks; instead it forms a hierarchy of timeservers and clients. Each level in this
hierarchy is called a stratum, and Stratum 1 is the highest level. Timeservers at this level synchronize them-
selves by means of a reference time source such as a radio controlled clock, satelliet receiver or modem time
distribution. Stratum 1 Servers distribute their time to several clients in the network which are called Stratum 2.
Highly precise synchronization is feasible because of the several time references. Every computer synchro-
nizes itself with up to three valued time sources. NTP enables the comparison of the hardware times and the
adjustment of the internal clock. A time precision of 128 ms, and often better than 1 ms, is possible.
5.1 NTP Clients
The NTP software package was tested on different UNIX systems. Almost all UNIX-like systems come with a
pre-installed NTP client software. In order to use the LANTIME as an NTP server, it is required to add its
IP address to the client configuration. NTP client software are available for most other operating systems like
Microsoft Windows or MAC OS.
The following WEB site is recommended to get the latest version of NTP:
http://www.ntp.org
You can find more information on our web page at:
https://www.meinbergglobal.com/english/sw/ntp.htm
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Date: 2nd July 2020
LANTIME CPU Expansion Shelf
Summary of Contents for LCES
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