The NTPv4 implementation includes provisions for an external clock, where the system clock is implemented by some external hardware device. diff --git a/html/filter.html b/html/filter.html index 0b6976321..5f9ed0abc 100644 --- a/html/filter.html +++ b/html/filter.html @@ -8,9 +8,9 @@

Clock Filter Algorithm

The clock filter algorithm processes the offset and delay samples produced by the on-wire protocol for each peer process separately. It uses a sliding window of eight samples and picks out the sample with the least expected error. This page describes the algorithm design principles along with an example of typical performance.

diff --git a/html/hints.html b/html/hints.html index a4e575929..7749ba9a1 100644 --- a/html/hints.html +++ b/html/hints.html @@ -9,9 +9,9 @@

Hints and Kinks

from Alice's Adventures in Wonderland, Lewis Carroll

Mother in law has all the answers.

- Modified: 11-Sep-2011 -

Last update: + 10-Mar-2014 05:06 + UTC

This is an index for a set of troubleshooting notes contained in individual text files in the ./hints directory. They were supplied by various volunteers in the form of mail messages, patches or just plain word of mouth. Each note applies to a specific computer and operating system and gives information found useful in setting up the NTP distribution or site configuration. The notes are very informal and subject to errors; no attempt has been made to verify the accuracy of the information contained in them.

diff --git a/html/hints/sco.html b/html/hints/sco.html index 97e7cf8ec..d5d1933b3 100644 --- a/html/hints/sco.html +++ b/html/hints/sco.html @@ -11,6 +11,9 @@

SCO Unix hints

Last update: + 21-Oct-2010 23:44 + UTC

Older SCO Unix versions

NTP 4.0.x does not run on SCO Unix prior to version 3.2.5.0.0. If you need NTP on an older SCO Unix system and don't mind to modify your kernel, use 3.5.91 which has patches for SCO Unix 3.2.4.x. Apply the kernel modifications as described in XNTP on SCO 3.2.4.2.

Compiling NTP

diff --git a/html/hints/solaris.html b/html/hints/solaris.html index 5c8b8fe65..4b83862e7 100644 --- a/html/hints/solaris.html +++ b/html/hints/solaris.html @@ -6,9 +6,12 @@ Information on compiling and executing ntpd under Solaris.
-Last Updated: Sun Jun 21 01:32:18 EDT 1998, +

Last update: + 27-Jan-2014 05:31 + UTC, John Hawkinson, <jhawk@MIT.EDU> +

If you're not running Solaris 2.5.1 or later, it is likely that you will have problems; upgrading would be a really good plan. diff --git a/html/hints/vxworks.html b/html/hints/vxworks.html index a617ded2c..eac9312f1 100644 --- a/html/hints/vxworks.html +++ b/html/hints/vxworks.html @@ -12,6 +12,9 @@

VxWorks port of NTP

Last update: + 21-Oct-2010 23:44 + UTC

Creating a port for vxWorks posed some problems. This port may help as a starting point for similar ports to real-time OS's and other embeddable kernels, particularly where main() is not allowed, and where the configure scripts need to be altered.

Configuration issues

I decided to do as little invasive surgery as possible on the NTP code, so I brought the vxWorks header tree in line with the standard Unix tree. The following changes were needed, as a side effect these changes will allow for easy porting of other autoconfigure enabled code.

diff --git a/html/history.html b/html/history.html index 59eb7d120..8b1ad5041 100644 --- a/html/history.html +++ b/html/history.html @@ -8,9 +8,9 @@

Historical Notes

- Modified: 03-Oct-2011 -

Last update: + 10-Mar-2014 05:07 + UTC

Historical Notes on NTP Upgrades

This is an interim report on recent upgrades to the NTPv4 reference implementation code base and documentation. This report documents the upgrade program, which began in June 2007 and continued until March 2008. It is very important to recognize that this historic document describes the upgrade status as of 2008. Additional upgrades have been implemented since then. As of mid 2011, the additional upgrades are documented on the NTP Version 4 Release Notes page.

diff --git a/html/howto.html b/html/howto.html index be23dc810..e89fa788e 100644 --- a/html/howto.html +++ b/html/howto.html @@ -10,9 +10,9 @@

How to Write a Reference Clock Driver

from Pogo, Walt Kelly

You need a little magic.

- Modified: 11-Sep-2010 -

Last update: + 10-Mar-2014 05:08 + UTC

The Huff-n'-Puff Filter

- Modified: 15-Nov-2012 -

Last update: + 10-Mar-2014 05:09 + UTC

In scenarios where a considerable amount of data are downloaded or uploaded using DSL or telephone modem lines, timekeeping quality can be seriously degraded. This occurs because the traffic volume, and thus the queuing delays, on the upload and download directions of transmission can be very different. In many cases the apparent time errors are so large as to exceed the step threshold and a step correction can occur during and after the data transfer.

The huff-n'-puff filter is designed to correct the apparent time offset in these cases. It depends on knowledge of the propagation delay when no other traffic is present, such as during other than work hours. The filter remembers the minimum delay over the most recent interval measured usually in hours. Under conditions of large delay, the filter corrects the apparent offset using the sign of the offset and the difference between the apparent delay and minimum delay. The name of the filter reflects the negative (huff) and positive (puff) correction, which depends on the sign of the offset. The filter is activated by the tinker huffpuff command, as described in the Miscellaneous Options page.

diff --git a/html/kern.html b/html/kern.html index e2392e153..b1660451b 100644 --- a/html/kern.html +++ b/html/kern.html @@ -10,9 +10,9 @@

Kernel Model for Precision Timekeeping

gif from Pogo, Walt Kelly

Alice finds the kernel a house of cards.

- Modified: 15-Nov-2012 -

Last update: + 10-Mar-2014 05:10 + UTC

PPSAPI Interface for Precision Time Signals

from NBS Special Publication 432, 1979 (out of print) -

- Modified: 11-Sep-2010 -

Last update: + 10-Mar-2014 05:10 + UTC

`ntp-keygen` - generate public and private keys

gif from Alice's Adventures in Wonderland, Lewis Carroll

Alice holds the key.

- Modified: 29-Nov-2012 -

Last update: + 10-Mar-2014 05:11 + UTC

Leap Second Processing

- Modified: 30-Nov-2012 -

Last update: + 10-Mar-2014 05:11 + UTC

About every eighteen months the International Earth Rotation Service (IERS) issues a bulletin announcing the insertion of a leap second in the Universal Coordinated Time (UTC) timescale. Ordinarily, this happens at the end of the last day of June or December; but, in principle, it could happen at the end of any month. While these bulletins are available on the Internet at www.iers.org, advance notice of leap seconds is also available in signals broadcast from national time and frequency stations, in GPS signals and in telephone modem services. Many, but not all, reference clocks recognize these signals and many, but not all, drivers for them can decode the signals and set the leap bits in the timecode accordingly. This means that many, but not all, primary servers can pass on these bits in the NTP packet heard to dependent secondary servers and clients. Secondary servers can pass these bits to their dependents and so on throughout the NTP subnet.

A leap second is inserted following second 59 of the last minute of the day and becomes second 60 of that day. A leap second is deleted by omitting second 59 of the last minute of the day, although this has never happened and is highly unlikely to happen in future. So far as is known, there are no provisions in the Unix or Windows libraries to account for this occasion other than to affect the conversion of an NTP datestamp or timestamp to conventional civil time.

diff --git a/html/miscopt.html b/html/miscopt.html index c110399cf..8eeac6127 100644 --- a/html/miscopt.html +++ b/html/miscopt.html @@ -9,9 +9,9 @@

Miscellaneous Commands and Options

from Pogo, Walt Kelly

We have three, now looking for more.

- Modified: 31-Jan-2014 -

Last update: + 31-Jan-2014 06:54 + UTC

Monitoring Commands and Options

from Pogo, Walt Kelly

Pig was hired to watch the logs.

- Modified: 31-Jan-2014 -

Last update: + 31-Jan-2014 06:54 + UTC

`ntpd` System Log Messages

from Alice's Adventures in Wonderland, Lewis Carroll

The log can be shrill at times.

- Modified: 11-Sep-2010 -

Last update: + 10-Mar-2014 05:12 + UTC

`ntp-wait` - waits until ntpd is in synchronized state

Last update: + 12-Jul-2011 22:03 + UTC

Synopsis

ntp-wait [ -v ] [ -n tries ] [ -s seconds ]

diff --git a/html/ntpd.html b/html/ntpd.html index 4d92ae9c5..418d199fb 100644 --- a/html/ntpd.html +++ b/html/ntpd.html @@ -11,9 +11,9 @@

`ntpd` - Network Time Protocol (NTP) Daemon

from The Wizard of Oz, L. Frank Baum

You need help from the monkeys.

- Modified: 10-Feb-2014 -

Last update: + 10-Mar-2014 05:14 + UTC

`ntpdate` - set the date and time via NTP

from Alice's Adventures in Wonderland, Lewis Carroll

I told you it was eyeball and wristwatch.

- Modified: 31-Jan-2014 -

Last update: + 9-Feb-2014 03:34 + UTC

Disclaimer: This program has known bugs and deficiencies and nobody diff --git a/html/ntpdc.html b/html/ntpdc.html index 38dd64083..7a68dd2f7 100644 --- a/html/ntpdc.html +++ b/html/ntpdc.html @@ -11,9 +11,9 @@

`ntpdc` - special NTP query program

from Alice's Adventures in Wonderland, Lewis Carroll

This program is a big, deprecated puppy.

-Modified: 31-Jan-2014 -

Last update: + 31-Jan-2014 06:54 + UTC

More Help

diff --git a/html/ntpdsim_new.html b/html/ntpdsim_new.html index 0081f74ee..54c67438a 100644 --- a/html/ntpdsim_new.html +++ b/html/ntpdsim_new.html @@ -10,9 +10,9 @@

`ntpdsim` - Network Time Protocol (NTP) Simulator

from The Wizard of Oz, L. Frank Baum

All in a row.

- Modified: 31-Jan-2014 -

Last update: + 31-Jan-2014 06:54 + UTC

`ntpq` - standard NTP query program

from Pogo, Walt Kelly

A typical NTP monitoring packet

- Modified: 31-Jan-2014 -

Last update: + 31-Jan-2014 06:54 + UTC

More Help

diff --git a/html/ntptrace.html b/html/ntptrace.html index cc3081997..bd47bd977 100644 --- a/html/ntptrace.html +++ b/html/ntptrace.html @@ -10,9 +10,9 @@

`ntptrace` - trace a chain of NTP servers back to the primary source

from Alice's Adventures in Wonderland, Lewis Carroll

The rabbit knows the way back.

- Modified: 31-Jan-2014 -

Last update: + 31-Jan-2014 06:54 + UTC

Synopsis

diff --git a/html/parsedata.html b/html/parsedata.html index f9815a1e2..4d3734b91 100644 --- a/html/parsedata.html +++ b/html/parsedata.html @@ -12,6 +12,9 @@

NTP PARSE clock data formats

The parse driver currently supports several clocks with different query mechanisms. In order for you to find a sample that might be similar to a clock you might want to integrate into parse I'll sum up the major features of the clocks (this information is distributed in the parse/clk_*.c and ntpd/refclock_parse.c files).

Last update: + 21-Oct-2010 23:44 + UTC

Meinberg clocks

diff --git a/html/parsenew.html b/html/parsenew.html
index 19ca72027..244612f84 100644
--- a/html/parsenew.html
+++ b/html/parsenew.html
@@ -11,6 +11,9 @@
 	
 		How to build new PARSE clocks
 		Here is an attempt to sketch out what you need to do in order to add another clock to the parse driver: Currently the implementation is being cleaned up - so not all information in here is completely correct. Refer to the included code where in doubt.
+Last update:
+  13-Oct-2010  00:33
+    UTC
 		Prerequisites:
 		
 			Does the system you want the clock connect to have the include files termio.h or termios.h ? (You need that for the parse driver)
diff --git a/html/poll.html b/html/poll.html
index cf9e5b100..aeb9c32cd 100644
--- a/html/poll.html
+++ b/html/poll.html
@@ -8,9 +8,9 @@
 
 
 Poll Process
-
-	Modified: 15-Nov-2012
-
+Last update:
+  10-Mar-2014  05:17
+    UTC
 
 The   poll process sends  NTP packets at intervals determined by the clock discipline algorithm.  The process is designed to provide a sufficient update rate to maximize accuracy while minimizing network overhead. The  process is designed to operate over a poll exponent range between 3 (8 s) and 17 (36 hr). The minimum and  maximum poll exponent within this range  can be set using the minpoll and maxpoll options of the server command, with default 6 (64 s) and 10 (1024 s), respectively.
  The poll interval is managed by a heuristic algorithm developed over several years of experimentation. It depends on an exponentially weighted  average of clock offset differences, called clock jitter, and a jiggle counter, which is initially set to zero.  When a clock update is received and the offset exceeds the clock jitter by a factor of 4,   the jiggle counter is increased by the poll exponent; otherwise, it is decreased by twice the poll exponent. If the jiggle counter is greater than an arbitrary threshold of 30,  it is reset to 0 and the the poll exponent is increased by 1.  If the jiggle counter is less than -30, it is set to 0 and the  poll exponent  decreased by 1. In effect, the algorithm has a relatively slow reaction to good news, but a relatively fast reaction to bad news.
diff --git a/html/pps.html b/html/pps.html
index 6d97bbd68..0b9bd5d49 100644
--- a/html/pps.html
+++ b/html/pps.html
@@ -10,9 +10,9 @@
 Pulse-Per-Second (PPS) Signal Interfacing
 from Alice's Adventures in Wonderland, Lewis Carroll
 Alice is trying to find the PPS signal connector.
-
-	Modified: 15-Nov-2012
-
+Last update:
+  10-Mar-2014  05:17
+    UTC
 

 Related Links
 
diff --git a/html/prefer.html b/html/prefer.html
index 91c068366..0fd0b8f4b 100644
--- a/html/prefer.html
+++ b/html/prefer.html
@@ -9,9 +9,9 @@
 Mitigation Rules and the prefer Keyword
  from Alice's Adventures in Wonderland, Lewis Carroll
 Listen carefully to what I say; it is very complicated.
-
-	Modified: 15-Nov-2012
-
+Last update:
+  10-Mar-2014  05:18
+    UTC
 

 Related Links
 
diff --git a/html/rate.html b/html/rate.html
index 8e241e5f7..2b47db80b 100644
--- a/html/rate.html
+++ b/html/rate.html
@@ -18,9 +18,9 @@ color: #FF0000;
 Rate Management and the Kiss-o'-Death Packet
 from Pogo, Walt Kelly
 Our junior managers and the administrators.
-
-	Modified: 15-Nov-2012
-
+Last update:
+  10-Mar-2014  05:19
+    UTC
 

 Related Links
 
diff --git a/html/rdebug.html b/html/rdebug.html
index 68366b67e..f14bf43c9 100644
--- a/html/rdebug.html
+++ b/html/rdebug.html
@@ -8,10 +8,10 @@
 
 Debugging Reference Clock Drivers
 from The Wizard of Oz, L. Frank Baum
-Call the girls and the'll sweep your bugs.
-
-	Modified: 11-Sep-2010
-
+Call the girls and they'll sweep your bugs.
+Last update:
+  10-Mar-2014  05:19
+    UTC
 

 Related Links
 
diff --git a/html/refclock.html b/html/refclock.html
index cb464e63c..78cc55e36 100644
--- a/html/refclock.html
+++ b/html/refclock.html
@@ -9,9 +9,9 @@
 
 Reference Clock Support
 Master Time Facility at the UDel Internet Research Laboratory
-
-    Modified: 01-Mar-2014
-
+Last update:
+  10-Mar-2014  05:20
+    UTC
 

 Related Links
 
diff --git a/html/select.html b/html/select.html
index 007126216..6cfa186d0 100644
--- a/html/select.html
+++ b/html/select.html
@@ -9,9 +9,9 @@
 
 
 Clock Select Algorithm
-
-	Modified: 15-Nov-2012
-
+Last update:
+  10-Mar-2014  05:22
+    UTC
 
 The clock select algorithm determines from a set of sources , which are correct (truechimers) and which are not (falsetickers) according to a set of formal correctness assertions. The principles are based on the observation that the maximum error in determining the offset of a candidate cannot exceed one-half the roundtrip delay to the primary reference clock at the time of measurement. This must be increased by the maximum error that can accumulate since then.  The selection metric, called the root  distance,, is one-half the roundtrip root delay plus the root dispersion plus minor error contributions not considered here.
 First, a number of sanity checks is performed to sift the selectable candidate from among the source population. The sanity checks are sumarized as follows:.
diff --git a/html/stats.html b/html/stats.html
index e61854487..943851773 100644
--- a/html/stats.html
+++ b/html/stats.html
@@ -8,9 +8,9 @@
 
 
 Performance  Metrics
-
-	Modified: 15-Nov-2012
-
+Last update:
+  10-Mar-2014  05:23
+    UTC
 Related Links
 
 
diff --git a/html/tickadj.html b/html/tickadj.html
index 830f2c2f6..3c38f844c 100644
--- a/html/tickadj.html
+++ b/html/tickadj.html
@@ -8,9 +8,9 @@
 
 
 tickadj - set time-related kernel variables
-
-	Modified: 11-Jul-2011
-
+Last update:
+  10-Mar-2014  05:24
+    UTC
 
 Synopsis
 tickadj [ -Aqs ] [ -a tickadj ] [ -t tick ]
diff --git a/html/warp.html b/html/warp.html
index da37a0f09..1d42dd63f 100644
--- a/html/warp.html
+++ b/html/warp.html
@@ -8,9 +8,9 @@
 
 
 How NTP Works
-
-	Modified: 15-Nov-2012
-
+Last update:
+  10-Mar-2014  05:24
+    UTC
 Related Links
 
 
diff --git a/html/xleave.html b/html/xleave.html
index 9f32b9ffc..417185cec 100644
--- a/html/xleave.html
+++ b/html/xleave.html
@@ -10,9 +10,9 @@
 NTP Interleaved Modes 
 from Pogo, Walt Kelly
 You need a little magic.
-
-	Modified: 15-Nov-2012
-
+Last update:
+  10-Mar-2014  05:25
+    UTC
 

 
 In the protocol described in the NTP specification and reference implementation up to now, the transmit timestamp, which is captured before the message digest is computed and the packet  queued for output,  is properly called as a softstamp The receive timestamp, which is captured after the input driver interrupt routine and before  the packet is queued for input,  is properly called  a drivestamp.  For enhanced accuracy it is desirable to capture the transmit timestamp  as close to the wire as possible; for example, after the output driver interrupt routine.

Association Management

Related Links

Command Index

Related Links

Build Options

Related Links

Copyright Notice

Event Messages and Status Words

Related Links

Clock Discipline Algorithm

Table of Contents

Automatic Server Discovery Schemes

Related Links

bc635VME/bc350VXI Time and Frequency Processor

Synopsis

Generic NMEA GPS Receiver

Synopsis

Hewlett Packard 58503A GPS Receiver and HP Z3801A

Synopsis

Arcron MSF Receiver

Synopsis

Shared Memory Driver

Synopsis

Trimble Palisade and Thunderbolt Receivers +Last update: + 21-Oct-2010 23:44 + UTC

Motorola Oncore GPS receiver

Synopsis

Rockwell Jupiter GPS receiver

Synopsis

Chrono-log K-series WWVB receiver

Synopsis

Dumb Clock

Synopsis

Ultralink Clock

Synopsis

Conrad parallel port radio clock

Synopsis

Forum Graphic GPS Dating station

Synopsis

hopf Serial Line Receivers (6021 and kompatible)

Synopsis

Questions or Comments:

hopf PCI-Bus Receiver (6039 GPS/DCF77)

Questions or Comments:

JJY Receivers

Synopsis

Zyfer GPStarplus Receiver

Synopsis

RIPE NCC interface for Trimble Palisade

Synopsis

NeoClock4X - DCF77 / TDF serial line receiver

Synopsis

Spectracom TSYNC PCI

Synopsis

GPSD NG client driver

Synopsis

IRIG Audio Decoder

Synopsis

Radio CHU Audio Demodulator/Decoder

Synopsis

Generic Reference Driver

Synopsis

Magnavox MX4200 GPS Receiver

Synopsis

MX4200 Receiver Data Format

Table of Contents

Motorola ONCORE - The Shared Memory Interface

Introduction

European Automated Computer Time Services

External Clock Discipline and the Local Clock Driver

Clock Filter Algorithm

Hints and Kinks

SCO Unix hints

Older SCO Unix versions

Compiling NTP

VxWorks port of NTP

Configuration issues

Historical Notes

Historical Notes on NTP Upgrades

How to Write a Reference Clock Driver

Related Links

Trimble Palisade and Thunderbolt Receivers +
Last update: + 21-Oct-2010 23:44 + UTC

`ntp-keygen` - generate public and private keys

`ntpd` System Log Messages

`ntp-wait` - waits until ntpd is in synchronized state

`ntpd` - Network Time Protocol (NTP) Daemon

`ntpdate` - set the date and time via NTP

`ntpdc` - special NTP query program

`ntpdsim` - Network Time Protocol (NTP) Simulator

`ntpq` - standard NTP query program

`ntptrace` - trace a chain of NTP servers back to the primary source

Mitigation Rules and the `prefer` Keyword

`tickadj` - set time-related kernel variables