Re: simple time server - NTP

This is a discussion on Re: simple time server - NTP ; >if you were expecting to >have to start a program everytime, you weren't particularly interested in >high accuracy. Sure I was. The program takes however long it needs to start up and then tells the client "The time right now ...

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Thread: Re: simple time server

  1. Re: simple time server

    >if you were expecting to
    >have to start a program everytime, you weren't particularly interested in
    >high accuracy.


    Sure I was. The program takes however long it needs to start up and
    then tells the client "The time right now is precisely ..." The
    client gets the message and knows that the time at that moment is that
    plus transmission delay. Ideally, it uses NTP so as to eliminate the
    transmission delay as well.

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    Bryan Henderson Phone 408-621-2000
    San Jose, California
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  2. Re: simple time server

    Bryan Henderson wrote:

    >>if you were expecting to
    >>have to start a program everytime, you weren't particularly interested in
    >>high accuracy.

    >
    >
    > Sure I was. The program takes however long it needs to start up and
    > then tells the client "The time right now is precisely ..." The
    > client gets the message and knows that the time at that moment is that
    > plus transmission delay. Ideally, it uses NTP so as to eliminate the
    > transmission delay as well.
    >


    It takes a couple of hours for the program to figure out "what the time
    is precisely". It can then tell some other system that the time, just a
    moment ago, was "precisely. . . ." That second system's notion of what
    time it is will be slightly less accurate than that of the first system.

    Once that first system has synchronized its clock, ntpd can maintain
    synchronization. If you shut down ntpd, you can expect to wait a while
    before it, again, figures out "precisely what time it is". Most people
    leave their NTP servers running 24x7 when possible.

    And NTP does not "eliminate the transmission delay". It assumes that
    the round trip delay is symmetrical and only if the delay is truly
    symmetrical does it account for the delay exactly.

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