Netware Super Library/Netware Super Library.iso/timevent/time868/time868.hlp

OS/2 Help File | 1995-08-30 | 15.4 KB | 391 lines

ΓòÉΓòÉΓòÉ 1. Help for TIME868 ΓòÉΓòÉΓòÉ

Use TIME868 to set your system clock using the Time Protocol. This protocol is
accurate to plus or minus one second. While OS/2 has the ability to keep time
to a fraction of a second (aprox. 1/32 second), most PC hardware does not have
the capability of setting time to a finer resolution than one second.

TIME868 provides a graph of the adjustments made for visual reference.

Related Information:

     Setting up the program
     Dialog fields
     USNO time server
     National Institute of Standards and Technology
     Choosing a time server
     About the Time Protocol
     Registering

 Copyright 1995, Norbert Dey


ΓòÉΓòÉΓòÉ 1.1. Help for Well-known sites ΓòÉΓòÉΓòÉ

This list contains several well-known sites providing time service plus two
customizable entries.

The list of sites is abstracted from the file clock.txt, in the pub/ntp/doc
directory and in the NTP distributions ntp.3.4 and xntp3 in the pub/ntp
directory, both on louie.udel.edu.

The sites selected for inclusion here are all Stratum 2 (not Stratum 1) and are
listed as open access. If you would like to use one of these sites on a regular
basis, it would be gracious to download the clock.txt file for the latest
status and to also observe the access policy listed.

In most cases, your local network or your service provider will already have a
sufficiently accurate clock for regular use.


ΓòÉΓòÉΓòÉ 2. Choosing a time server ΓòÉΓòÉΓòÉ

The basic reason for synchronizing your computer's clock is so that your value
for a particular increment of time is the same or very close to the value used
by your colleagues.

You have two basic choices: you can all synchronize to the same clock or you
can all synchronize to one of several standard clocks.

If you have no need for the exact standard value for the time, you can simply
all synchronize to a conveniently available clock. In many applications, only a
comparison of times is necessary ... this file was created after that file ...
and so forth. As long as the clock is accurate to ordinary human standards (a
minute or so), this is sufficient.

If it is impractical for all of your colleagues to synchronize to the same
clock, you will need to find a server which itself is traceable to a precise
standard clock.

Some Internet service providers and larger institutions will provide time
service which is synchronized to a standard time source. If you have a local
source of accurate time, it is your best choice for a time server.

All of the servers listed by this program are Stratum 2 or better in NTP terms.
This means that they are normally very good clocks. (Sometimes they may have
problems and drift off. A suspicious time should be checked against another
server.)

Not all of the servers listed provide service on both TCP and UDP protocols. If
one protocol does not work, try the other.

Another factor in the choice is the distance to the server in network time. A
server with a long delay will give poorer results than a server with a short
delay. Long delays are perhaps due to network congestion over that route and
therefore will be quite variable. Since the time value being returned by the
server is the time at which the packet left the server, its accuracy depends on
a quick trip to your system.

The network latency is reported in the log. This is calculated as 1/2 of the
total round trip on the assumption that the delay is symetrical.

A useful comparison is the difference between the latency of the selected
server and your Internet provider or gateway.


ΓòÉΓòÉΓòÉ 3. Help for dialog fields ΓòÉΓòÉΓòÉ

The following panels describe the dialog fields.

 Site      selection

 Hostname  of server

 IP        address of server

 TCP       Protocol support

 UDP       Protocol support

 Log       text window

 Graph     of history

 Delay     for Auto-run

 Interval  between samples

 Run       button

 Help      button

 Auto-run  feature

 Continuous Continuous running


ΓòÉΓòÉΓòÉ 3.1. Help for Hostname ΓòÉΓòÉΓòÉ

Enter the hostname here. Use the full name, such as tick.usno.navy.mil. If the
IP address is specified, then this field need not be used.


ΓòÉΓòÉΓòÉ 3.2. Help for IP address ΓòÉΓòÉΓòÉ

If the IP address is known, enter it here. If there are any characters in this
field, the program will try to use this as an IP address.

If you don't know (or are unsure of) the IP address, just leave it blank and
the program will consult the nameserver. The IP address found will be stored
for the next use.


ΓòÉΓòÉΓòÉ 3.3. Help for TCP radio button ΓòÉΓòÉΓòÉ

If the site provides the Time service via TCP, check this button. If you are
uncertain, just give it a try. If the service is not provided, the request will
time out in a few seconds.


ΓòÉΓòÉΓòÉ 3.4. Help for UDP radio button ΓòÉΓòÉΓòÉ

If the site provides the Time service via UDP, check this button. If you are
uncertain, just give it a try. If the service is not provided, the request will
time out in a few seconds.


ΓòÉΓòÉΓòÉ 3.5. Help for log ΓòÉΓòÉΓòÉ

The log is a record of the actions taken when processing a request for the
time. It also records any errors encountered.


ΓòÉΓòÉΓòÉ 3.6. Help for graph ΓòÉΓòÉΓòÉ

The graph record the last 20 results for this server. Each server is recorded
separately. The horizontal black line is the local notion of UTC. The green
band across the center of the graph indicates the span of plus and minus 1
second from local UTC.

The horizontal scale is the time from the first of the 20 samples to the last.
Samples taken closely together in time will appear close together on the graph.

The red line indicates the amount of adjustment necessary to the local clock. A
value above the center line indicates that the local clock was ahead, while
below indicates behind.

If everything is working well, the red line will stay within the green band
once the inital correction is made. If the red line is consistantly above the
green band, then your clock is running fast. If it is consistently below the
green band, then it is running slow.


ΓòÉΓòÉΓòÉ 3.7. Help for delay ΓòÉΓòÉΓòÉ

When Auto-run is selected, the program will wait this number of seconds before
taking the sample. The minimum value is 5 seconds to allow time for the user to
cancel the Auto-run.

The Auto-run may be cancelled by simply clicking on the check-box.


ΓòÉΓòÉΓòÉ 3.8. Help for interval ΓòÉΓòÉΓòÉ

When continuous run is selected, the program will check the time at this
interval. The minimum value is 1 hour. There is no value in checking more often
than this. In fact, there is little to be gained by checking more than once per
day. This minimum also prevents a bombardment of the server with requests.


ΓòÉΓòÉΓòÉ 3.9. Help for Run ΓòÉΓòÉΓòÉ

Pressing this button will check the time immediately.


ΓòÉΓòÉΓòÉ 3.10. Help for Help ΓòÉΓòÉΓòÉ

Select the menu item Help above for using Help. Select for General Help.


ΓòÉΓòÉΓòÉ 3.11. Help for Auto-run ΓòÉΓòÉΓòÉ

When this is selected, the program will automatically check the time after a
short delay. If continuous running is not selected, the program will then exit.


ΓòÉΓòÉΓòÉ 3.12. Help for Continuous ΓòÉΓòÉΓòÉ

When this is selected, the program will check the time each interval.


ΓòÉΓòÉΓòÉ 4. Other Information ΓòÉΓòÉΓòÉ

     About the Time Protocol
     USNO time server
     National Institute of Standards and Technology
     UTC


ΓòÉΓòÉΓòÉ 4.1. Time Protocol ΓòÉΓòÉΓòÉ

 Network Working Group

 Request for Comments: 868

 J. Postel - ISI

 K. Harrenstien - SRI

           May 1983

 Time Protocol

 This RFC specifies a standard for the ARPA Internet community.  Hosts on the
 ARPA Internet that choose to implement a Time Protocol are expected to adopt
 and implement this standard.

 This protocol provides a site-independent, machine readable date and time.
 The Time service sends back to the originating source the time in seconds
 since midnight on January first 1900.

 One motivation arises from the fact that not all systems have a date/time
 clock, and all are subject to occasional human or machine error.  The use of
 time-servers makes it possible to quickly confirm or correct a system's idea
 of the time, by making a brief poll of several independent sites on the
 network.

 This protocol may be used either above the Transmission Control Protocol (TCP)
 or above the User Datagram Protocol (UDP).

 When used via TCP the time service works as follows:

   S: Listen on port 37 (45 octal).

   U: Connect to port 37.

   S: Send the time as a 32 bit binary number.

   U: Receive the time.

   U: Close the connection.

   S: Close the connection.

 The server listens for a connection on port 37.  When the connection is
 established, the server returns a 32-bit time value and closes the connection.
 If the server is unable to determine the time at its site, it should either
 refuse the connection or close it without sending anything.

 When used via UDP the time service works as follows:

   S: Listen on port 37 (45 octal).

   U: Send an empty datagram to port 37.

   S: Receive the empty datagram.

   S: Send a datagram containing the time as a 32 bit binary number.

   U: Receive the time datagram.

 The server listens for a datagram on port 37.  When a datagram arrives, the
 server returns a datagram containing the 32-bit time value.  If the server is
 unable to determine the time at its site, it should discard the arriving
 datagram and make no reply.

 The Time

 The time is the number of seconds since 00:00 (midnight) 1 January 1900 GMT,
 such that the time 1 is 12:00:01 am on 1 January 1900 GMT; this base will
 serve until the year 2036.

 For example:

 the time  2,208,988,800 corresponds to 00:00  1 Jan 1970 GMT,

 2,398,291,200 corresponds to 00:00  1 Jan 1976 GMT,

 2,524,521,600 corresponds to 00:00  1 Jan 1980 GMT,

 2,629,584,000 corresponds to 00:00  1 May 1983 GMT,

 and -1,297,728,000 corresponds to 00:00 17 Nov 1858 GMT.


ΓòÉΓòÉΓòÉ 4.2. U.S. Naval Observatory ΓòÉΓòÉΓòÉ

The U.S. Naval Observatory has established two new network time servers for
reliable, accurate time over the Internet and Milnet WANS:

 tick.usno.navy.mil 192.5.41.40

 tock.usno.navy.mil 192.5.41.41

 These HP9000/747i systems host Datum VME synchronized generators using IRIG-b
 timecode from USNO Master Clock #2. The system clocks of these servers are
 synchronized to within a few tens of microseconds of USNO Master Clock 2.

 UTC(USNO) is provided over the network via a number of protocols. At present,
 access is unrestricted.


ΓòÉΓòÉΓòÉ 4.3. National Institute of Standards and Technology ΓòÉΓòÉΓòÉ

NIST (National Institute of Standards and Technology) provides time service at
time.nist.gov (132.163.135.130).

The NIST Network Time Server is synchronized to the NIST cesium clock ensemble.
The server transmits time using three common internet protocols:  tcp/ip,
udp/ip and NTP (Network Time Protocol).


ΓòÉΓòÉΓòÉ 4.4. Universal Time, Coordinated ΓòÉΓòÉΓòÉ

This is also known as GMT (Greenwich Mean Time) and Zulu (Zero) time. UTC is an
international standard for reporting time.

The zero meridian crosses Greenwich, England, home of the Royal Observatory.


ΓòÉΓòÉΓòÉ 5. Setup ΓòÉΓòÉΓòÉ

Before starting to use the program, check to see if your clock is somewhat
close to the correct time. If your clock is more than 4-5 minutes slow, the
first correction may trick your dialer into thinking that the idle time has
exceeded its limit and disconnect you.

If this happens, just reconnect. The first correction has already been made and
the next try will cause no problems.

The Auto-run feature was designed for those of us who are only connected to the
Internet once or twice a day. When this feature is selected, the program will
wait for the specified delay, then get the time and exit.

The initial delay should be set just long enough for the initial burst of
network traffic (the newsreader starting, etc) to settle down. If TIME868 is
competing with everything else for your PPP or SLIP link, the delays may be too
long for accurate time collection.

If you have a permanent connection to the Internet or to a time-server on a
LAN, you may wish to keep the program running and use the  Continuous running
feature to check the time periodically. Once or twice a day should be all that
is necessary.

The program will run fine while minimized.


ΓòÉΓòÉΓòÉ 6. Registering the program ΓòÉΓòÉΓòÉ

TIME868 is freeware. A picture postcard or an email note is appreciated.

      Norbert Dey
      PO Box 103
      Newberg OR 97132
      USA

 Bug reports and suggestions may be sent to [e-mail]

 Thank you, Norbert Dey

 DISCLAIMER

 The author of this program accepts no responsibility for damages that are
 caused by this program and make NO WARRANTY or representation, either express
 or implied, with respect to this software.  This software is provided "AS IS,"
 and you assume the entire risk when you use it.


ΓòÉΓòÉΓòÉ <hidden>  ΓòÉΓòÉΓòÉ

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