[Git][NTPsec/ntpsec][master] 2 commits: Added the history document.

[Eric S. Raymond]

Eric S. Raymond pushed to branch master at NTPsec / ntpsec


Commits:
2e1da2e1 by Eric S. Raymond at 2019-01-13T00:22:51Z
Added the history document.

- - - - -
7771778e by Eric S. Raymond at 2019-01-13T00:22:51Z
Link the history documrnt to the index page.

- - - - -


2 changed files:

- + docs/history.adoc
- docs/index.adoc


Changes:

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docs/history.adoc
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@@ -0,0 +1,62 @@
+== History of NTP ==
+
+// Early history was found at https://www.galsys.co.uk/about-NTP.html
+
+The first NTP implementation started around 1980 with an accuracy of
+only several hundred milliseconds. That very first implementation was
+documented in Internet Engineering Note
+https://www.rfc-editor.org/ien/ien175.txt[IEN-173]. Later the first
+specification appeared in
+https://www.rfc-editor.org/rfc/rfc778.txt[RFC 778], but it was still
+named Internet Clock Service. At that time clock synchronization was
+needed for the HELLO routing protocol. NTP was introduced in
+https://tools.ietf.org/rfc/rfc958.txt[RFC 958] for the first time,
+mainly describing the packets seen on the network as well as some
+basic calculations involved. Early versions of NTP did not compensate
+any frequency error.
+
+The first complete specification of the protocol and accompanying
+algorithms for NTP version 1 appeared 1988 in
+https://tools.ietf.org/rfc/rfc1059.txt[RFC 1059]. That version already
+had symmetric operation mode as well as client-server mode.
+
+Version 2 introducing symmetric-key authentication (using DES-CBC) was
+described in https://tools.ietf.org/rfc/rfc1119.txt[RFC 1119] only
+about one year later. About the same time another time synchronization
+protocol named Digital Time Synchronization Service (DTSS) was
+presented by Digital Equipment Corporation. At that time the software
+named xntp was written by Dennis Fergusson at the University of
+Toronto. That software evolved to the software distribution that is
+publicly available now.
+
+Combining the good ideas of DTSS with those of NTP produced a new
+specification for NTP version 3, namely
+https://tools.ietf.org/rfc/rfc1992.txt[RFC 1305], in 1992. That
+version introduced formal correctness principles and revised
+algorithms. Furthermore broadcast mode was added to the protocol.
+
+While NTP per se only deals with adjusting the operating system's
+clock, there was some parallel research on improving time keeping
+within the operating system's
+kernel. https://tools.ietf.org/rfc/rfc1589.txt[RFC 1589] (A kernel
+model for precision timekeeping) described a new implementation and
+interface in 1994. That implementation could keep time with a
+precision of up to one microsecond.
+
+While version 3 was still the latest specification available, both,
+the specification and the implementation has been continuously
+improved (this is what xntp3-5 actually implements). Since about 1994
+work for a new version of NTP is in progress. The first new
+specification was https://tools.ietf.org/rfc/rfc2030.txt[RFC 2030],
+Simple Network Time Protocol (SNTP) version 4 for IPv4, IPv6 and OSI.
+This issued in 1996.
+
+External pulses can be used to calibrate and stabilize the operating
+system's clock. Therefore an operating system interface (API) has been
+designed and documented in https://tools.ietf.org/rfc/rfc2783.txt[RFC
+2783] (Pulse-per-second API for Unix-like operating systems, version
+1), finally published in 1999.  This is now implemented in all
+modern Unixes.
+
+
+


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docs/index.adoc
=====================================
@@ -167,6 +167,8 @@ bibliography and briefing slides suitable for presentations are on the
 Synchronization Research Project] page. Additional information is at
 the NTPsec web site {project-weblink}.
 
+You can also read a brief link:history.html[history of NTP].
+
 '''''
 
 image::pic/pogo1a.gif[align="center"]



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