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Annotation of embedaddon/ntp/html/hints/notes-xntp-v3, revision 1.1.1.1

1.1 misho 1: Notes for NTP Version 3
2:
3: This version operates in much the same manner as Version 2 with the
4: following changes and additions:
5:
6: 1. The protocol machinery operates in conformance with the RFC1305 NTP
7: Version 3 specification. The most visible characteristic of this
8: version is that the poll intervals for all polls, even selected
9: ones, is significantly increased. This is especially desirable when
10: serving a large client population. This implementation supports
11: previous versions as non-configured peers; for version-2 configured
12: peers a "version 2" keyword should be included on the "peer" line.
13:
14: 2. The configuration file has a new keyword: statfile <file>, where
15: <file> is the name of a statistics file." When present, each clock
16: update generates an entry of the form:
17:
18: <day> <sec>.<frac> <addr> <status> <offset> <delay> <disp>
19:
20: where <day> is the modified Julian day, <sec>.<frac> is the time of
21: day, <addr> is the peer address and <status> is the peer status.
22: The <offset>, <delay> and <disp> are the measured offset, delay and
23: dispersion, respectively, of the peer clock relative to the local
24: clock. About once per day the current file is closed and a new one
25: created with names <file>.<gen>, where <gen> starts at one and
26: increments for each new generation.
27:
28: 3. A number of additional platforms are supported. See ./Config file
29: for details.
30:
31: 4. A driver for the TrueTime 468DC GOES Synchronized Clock is
32: included. This driver (refclock_goes.c) should also work for other
33: TrueTime radio clocks, since all use the same format.
34:
35: 5. A replacement driver for the Spectracom 8170 WWVB Synchronized
36: Clock is included. This driver (refclock_wwvb.c) (a) does not
37: require a 1-pulse-per-second signal, (b) supports both format 0
38: (original 8170) and format 2 (Netclock/2 and upgraded 8170), (c)
39: can be connected to more than one computer and (d) automatically
40: compensates for all serial baud rates.
41:
42: 6. A driver for the German time/frequency station DCF77 is included.
43: This requires a special STREAMS module.
44:
45: 7. In Version 2 special line-discipline modules were required for the
46: CHU and WWVB drivers. This code continues to work in Version 3,
47: although it is no longer needed for the WWVB driver. However, this
48: code does not work under STREAMS, as used in SunOS 4.1.1.
49: Equivalent STREAMS modules are supplied with Version 3.
50:
51: 8. Support for an external 1-pulse-per-second (pps) signal is
52: provided. The signal is connected to a serial port (see
53: xntpd/ntp_loopfilter.c for details). When present the leading edge
54: of the pulse establishes the on-time epoch within an interval
55: established by the selected radio clock or other NTP time server.
56: Use of the pps is indicated when the tattletale displayed by ntpq
57: changes from "*" to "o".
58:
59: 9. The clock-selection and poll-update procedures have been modified
60: slightly in order to achieve better performance on high speed LANs
61: with compromise in performance on typical WANs.
62:
63: 10. In order to comply with U.S. Commerce Department regulations, the DES
64: encryption routine lib/authdes.c cannot be exported. For exportable
65: versions of this distribution a DES-encrypted version of this routine
66: lib/authdes.c.des is included along with an unencrypted version
67: lib/authdes.c.export, which allows normal operation, but without the
68: NTP authentication feature. Further information is available in the
69: lib/authdes.c.export file.
70:
71: 11. As an alternative to the DES-based authentication mechanism, an
72: implementation of the RSA Message Digest 5 algorithm is provided.
73: (see applicable copyright information in the library files).
74:
75: 12. A driver for the Magnavox MX4200 GPS clock.
76:
77: 13. A STREAMS module which captures carrier-detect data-lead transitions to
78: connect a precision source of 1-pps, yet avoid the ugly overhead in the
79: usual STREAMS processing. See the ppsclock subdirectory.
80:
81: 14. Support for the Apple A/UX operating system and enhanced support for the
82: Hewlet-Packard HP/UX operating system. See the various README and Config
83: files for further information.
84:
85: See the COPYRIGHT file for authors and copyright information. Note that some
86: modules in this distribution contain copyright information that supersedes
87: the copyright information in that file.
88:
89: If I missed something or neglected to give due credit, please advise.
90:
91: David L. Mills
92: University of Delaware
93: 31 May 1992, amended 23 July 1992, 25 October 1992
94:
95: Bugs and notes
96:
97: A bug in the original tty_clk_STREAMS.c module has been fixed.
98:
99: The poll-interval randomization feature of poll_update (in
100: xntpd/ntp_proto.c) has been extended to apply when the poll interval is
101: increased, as well as reduced. This spreads the update messages in time
102: and helps avoid unpleasant bursts of messages.
103:
104: In the clock_select algorithm the peers selected for combining are
105: limited to those survivors at the lowest stratum, not the entire list.
106: This helps avoid whiplash when large numbers of peers are at the same
107: stratum.
108:
109: The number formerly displayed by ntpq as "compliance" is now the time
110: constant of integration.
111:
112: The DNS resolver xntpd/ntp_intres.c is now integrated into xntpd, making
113: configuration of multiple hosts easier.
114:
115: System and peer event are now written to the system log at priority
116: LOG_INFO.
117:
118: The leap-second code was fixed to avoid broadcasting leap warnings on
119: all except the last day of June and December.

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