Using ntpdate -b SERVER shortly after SERVER boots - NTP

This is a discussion on Using ntpdate -b SERVER shortly after SERVER boots - NTP ; Uwe Klein wrote: > Richard B. gilbert wrote: [] >> That's an interesting article but it misuses the word "precision". >> Precision is a property of your clock and can be thought of as the >> smallest possible difference in ...

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Thread: Using ntpdate -b SERVER shortly after SERVER boots

  1. Re: Fwd: Using ntpdate -b SERVER shortly after SERVER boots

    Uwe Klein wrote:
    > Richard B. gilbert wrote:

    []
    >> That's an interesting article but it misuses the word "precision".
    >> Precision is a property of your clock and can be thought of as the
    >> smallest possible difference in time that the clock can measure.

    >
    > isn't that "resolution" ?
    > iananes ( i am not a native english speaker ;-)
    >>
    >> A clock can have a precision of 1 microsecond and still be five
    >> minutes slow!
    >>

    >
    > uwe


    Uwe,

    I suspect these terms mean what you choose them to mean. Here is what
    Google has to offer:

    http://www.google.com/search?sourcei...e%3a+precision

    (includes both "number of digits" and "degree of refinement")

    http://www.google.com/search?hl=en&r...on&btnG=Search

    (includes "measure of accuracy or dynamic range of an A/D or D/A
    converter" and "smallest quantity that can be measured").

    From this, I would suggest:

    precision - degree of correctness

    resolution - accuracy of measurement

    Perhaps NTP has its own definitions?

    Cheers,
    David



  2. Re: Using ntpdate -b SERVER shortly after SERVER boots

    Brian Garrett wrote:
    > "Richard B. gilbert" wrote in message


    >>You have NO IDEA how fierce the competition for that prize is!!!!!
    >>
    >>

    >
    > I always assumed it was a dead heat between Netgear and D-Link

    Thats the _other_ prize you're talking about!
    >
    > Brian

    uwe

    >
    >


  3. Re: Using ntpdate -b SERVER shortly after SERVER boots

    Brian Garrett wrote:
    > "Richard B. gilbert" wrote in message
    > news:45D13610.2020705@comcast.net...
    >
    >>Donald Murray, P.Eng. wrote:
    >>
    >>>On 10 Feb 2007 02:16:02 GMT, Steve Kostecke

    >>

    > wrote:
    >
    >>>>On 2007-02-08, Donald Murray, P.Eng. wrote:
    >>>>
    >>>>
    >>>>
    >>>>>How quickly can an isolated ntp server respond to 'ntpdate' queries
    >>>>>after the server starts?
    >>>>

    >>
    >>
    >>>I bet this sounds pretty awful to most of you. It sounds kind of awful
    >>>to me as well.
    >>>
    >>>Thanks for your suggestions. I appreciate everyone taking the time to

    >>

    > respond.
    >
    >>>Do I get a prize for most inappropriate use of ntp? ;-)

    >>
    >>
    >>You have NO IDEA how fierce the competition for that prize is!!!!!
    >>
    >>

    >
    > I always assumed it was a dead heat between Netgear and D-Link
    >
    > Brian
    >
    >


    I don't know about a "dead heat" but there's no doubt in my mind that
    it's fierce competition. The people trying to us NTP to "synchronize
    clocks to each other" without reference to UTC can be found under any rock!


  4. Re: Fwd: Using ntpdate -b SERVER shortly after SERVER boots

    Uwe Klein wrote:
    > Richard B. gilbert wrote:
    >
    >> Harlan Stenn wrote:
    >>
    >>> Donald,
    >>>
    >>> Have you seen http://ntp.isc.org/Support/StartingNTP4 ?
    >>>
    >>> H

    >>
    >>
    >>
    >>
    >> That's an interesting article but it misuses the word "precision".


    > isn't that "resolution" ?
    > iananes ( i am not a native english speaker ;-)


    Don't worry about it. Your English is SO much better than my Deutch.
    (I can make a few polite noises in Español, Deütch, Nihongo (Japanese)
    and Turkish). I'm fluent only in English and it could be argued
    convincingly that I'm not fluent in English either!

    Resolution is a good synonym but NTP usage describes the "precision" of
    a clock in terms of the value of the least significant bit or the
    smallest measurable interval. I think RFC-1305 defines precision
    somewhere but it's hard to find without reading cover-to-cover. I hope
    the V4 RFC has an index!!


    >
    > uwe
    >



  5. Re: Using ntpdate -b SERVER shortly after SERVER boots


    Dear Sir Gilbert, Hello Richard,

    Richard B. gilbert wrote:

    > it's fierce competition. The people trying to us NTP to "synchronize
    > clocks to each other


    I am well aware of what design goals are the underpinning of ntp(d).

    On the other hand i have a bag full of situations where
    I want to sync a set of boxes to each other ( somehow )
    but have no requirement for sync to "The Clock".

    Now if I do not have the requirement i am rather keen on
    not trapping myself by dependence on some external service.

    I can understand the ire of the developers and maintainers
    if their core achievement is simply ignored.

    But the pertinent question in this context is _not_:

    is tnpd designed for this setup?

    BUT

    is ntpd suitable for this type of setup.

    A very good idea would be to include some information
    on how to set up an isolated sync domain
    and what to watch out for to get good sync quality.

    This would probably answer about 1/3 of question placed
    in this news group.

    Would a "private" flag in protocol data then be a good idea?


    uwe





  6. Re: Fwd: Using ntpdate -b SERVER shortly after SERVER boots

    David J Taylor wrote:
    > Uwe Klein wrote:
    >
    >>Richard B. gilbert wrote:

    >
    > []
    >
    >>>That's an interesting article but it misuses the word "precision".
    >>>Precision is a property of your clock and can be thought of as the
    >>>smallest possible difference in time that the clock can measure.

    >>
    >>isn't that "resolution" ?
    >>iananes ( i am not a native english speaker ;-)
    >>
    >>>A clock can have a precision of 1 microsecond and still be five
    >>>minutes slow!
    >>>

    >>
    >>uwe

    >
    >
    > Uwe,
    >
    > I suspect these terms mean what you choose them to mean. Here is what
    > Google has to offer:
    >
    > http://www.google.com/search?sourcei...e%3a+precision
    >
    > (includes both "number of digits" and "degree of refinement")
    >
    > http://www.google.com/search?hl=en&r...on&btnG=Search
    >
    > (includes "measure of accuracy or dynamic range of an A/D or D/A
    > converter" and "smallest quantity that can be measured").
    >
    > From this, I would suggest:
    >
    > precision - degree of correctness
    >
    > resolution - accuracy of measurement
    >
    > Perhaps NTP has its own definitions?


    Indeed it does! See RFC-1305 page 11.


  7. Resolution and Precision (was: Using ntpdate -b SERVER shortly after SERVER boots)

    Richard B. gilbert wrote:
    > David J Taylor wrote:

    []
    >> From this, I would suggest:
    >>
    >> precision - degree of correctness
    >>
    >> resolution - accuracy of measurement
    >>
    >> Perhaps NTP has its own definitions?

    >
    > Indeed it does! See RFC-1305 page 11.


    Thanks, but I don't see page numbers here:

    http://www.faqs.org/rfcs/rfc1305.html

    Nor can I quickly see the definitions...

    David



  8. Re: Fwd: Using ntpdate -b SERVER shortly after SERVER boots

    Richard B. gilbert wrote:
    > Uwe Klein wrote:
    >
    >> Richard B. gilbert wrote:
    >>
    >>> Harlan Stenn wrote:
    >>>
    >>>> Donald,
    >>>>
    >>>> Have you seen http://ntp.isc.org/Support/StartingNTP4 ?
    >>>>
    >>>> H
    >>>
    >>>
    >>>
    >>>
    >>>
    >>> That's an interesting article but it misuses the word "precision".

    >
    >
    >> isn't that "resolution" ?
    >> iananes ( i am not a native english speaker ;-)

    >
    >
    > Don't worry about it. Your English is SO much better than my Deutch. (I
    > can make a few polite noises in Español, Deütch, Nihongo (Japanese) and
    > Turkish). I'm fluent only in English and it could be argued
    > convincingly that I'm not fluent in English either!
    >
    > Resolution is a good synonym but NTP usage describes the "precision" of
    > a clock in terms of the value of the least significant bit or the
    > smallest measurable interval. I think RFC-1305 defines precision
    > somewhere but it's hard to find without reading cover-to-cover. I hope
    > the V4 RFC has an index!!


    What about a glossary of terms used?

    uwe

  9. Re: Resolution and Precision

    David J Taylor wrote:

    > Thanks, but I don't see page numbers here:
    >
    > http://www.faqs.org/rfcs/rfc1305.html
    >
    > Nor can I quickly see the definitions...
    >
    > David
    >
    >

    This?:
    Many if not most Internet timekeeping systems
    can tolerate jitter to at least the order of

    the intrinsic local-clock resolution,
    called precision in the NTP specification,

    which is commonly in the range from one to 20 ms.

    uwe

  10. Re: Resolution and Precision

    Uwe Klein wrote:
    > David J Taylor wrote:
    >
    >> Thanks, but I don't see page numbers here:
    >>
    >> http://www.faqs.org/rfcs/rfc1305.html
    >>
    >> Nor can I quickly see the definitions...
    >>
    >> David
    >>
    >>

    > This?:
    > Many if not most Internet timekeeping systems
    > can tolerate jitter to at least the order of
    >
    > the intrinsic local-clock resolution,
    > called precision in the NTP specification,
    >
    > which is commonly in the range from one to 20 ms.
    >
    > uwe


    Who knows?

    In documents I was required to write, ambiguous terms like this were
    properly defined. The Internet documents usually define terms like "may",
    " should", "must" etc. for different levels of compulsion in requirements.

    Yes, a glossary (in the Wiki?) would be an excelletnt idea.

    Cheers,
    David



  11. Re: Resolution and Precision

    David,

    RFC 1305 was the seat of furious controversy. I consider the only
    authorative document is in PostScript, later in PDF. The IETF and I have
    engaged in serious disagreement on PDF formats as against Postel ASCII.
    Everything, and I mean everything today is in PDF - Governent documents
    and forms, University documents and forms, IEEE standards, ACM and IEEE
    publications and everything else I do is in PDF. So, what you see is
    what you get. The PDF of RFC 1305 is on the NTP project page.

    Dave

    David J Taylor wrote:

    > Richard B. gilbert wrote:
    >
    >>David J Taylor wrote:

    >
    > []
    >
    >>>From this, I would suggest:
    >>>
    >>>precision - degree of correctness
    >>>
    >>>resolution - accuracy of measurement
    >>>
    >>>Perhaps NTP has its own definitions?

    >>
    >>Indeed it does! See RFC-1305 page 11.

    >
    >
    > Thanks, but I don't see page numbers here:
    >
    > http://www.faqs.org/rfcs/rfc1305.html
    >
    > Nor can I quickly see the definitions...
    >
    > David
    >
    >


  12. Re: Resolution and Precision (was: Using ntpdate -b SERVER shortlyafter SERVER boots)

    David J Taylor wrote:
    > Richard B. gilbert wrote:
    >
    >>David J Taylor wrote:

    >
    > []
    >
    >>>From this, I would suggest:
    >>>
    >>>precision - degree of correctness
    >>>
    >>>resolution - accuracy of measurement
    >>>
    >>>Perhaps NTP has its own definitions?

    >>
    >>Indeed it does! See RFC-1305 page 11.

    >
    >
    > Thanks, but I don't see page numbers here:
    >
    > http://www.faqs.org/rfcs/rfc1305.html
    >
    > Nor can I quickly see the definitions...
    >
    > David
    >
    >


    Dave Mills has a version, I think it's in PDF, that has page numbers.
    Look under section 3.2.1, common variables.
    http://www.eecis.udel.edu/~mills/database/rfc/rfc1305/


  13. Re: Fwd: Using ntpdate -b SERVER shortly after SERVER boots

    Uwe Klein wrote:
    > Richard B. gilbert wrote:
    >
    >> Uwe Klein wrote:
    >>
    >>> Richard B. gilbert wrote:
    >>>
    >>>> Harlan Stenn wrote:
    >>>>
    >>>>> Donald,
    >>>>>
    >>>>> Have you seen http://ntp.isc.org/Support/StartingNTP4 ?
    >>>>>


    >>>> That's an interesting article but it misuses the word "precision".
    >>>

    >>
    >>
    >>> isn't that "resolution" ?
    >>> iananes ( i am not a native english speaker ;-)

    >>
    >>
    >>
    >> Don't worry about it. Your English is SO much better than my Deutch.
    >> (I can make a few polite noises in Español, Deütch, Nihongo (Japanese)
    >> and Turkish). I'm fluent only in English and it could be argued
    >> convincingly that I'm not fluent in English either!
    >>
    >> Resolution is a good synonym but NTP usage describes the "precision"


    >
    > What about a glossary of terms used?
    >
    > uwe


    A glossary would help too. At 113 8-1/2x11" pages, it's a fair sized
    book and both an index and a glossary would be appropriate additions.


  14. Re: Fwd: Using ntpdate -b SERVER shortly after SERVER boots

    >>> In article <5o89a4-3sb.ln1@robert.houseofmax.de>, Uwe Klein writes:

    Uwe> What about a glossary of terms used?

    http://ntp.isc.org/Support/NTPRelatedDefinitions

    H

  15. Re: Using ntpdate -b SERVER shortly after SERVER boots

    On 2007-02-13, Richard B. gilbert wrote:
    > Brian Garrett wrote:


    > [---=| Quote block shrinked by t-prot: 27 lines snipped |=---]


    Please trim the quoted material in your articles.

    > The people trying to us NTP to "synchronize clocks to each other"
    > without reference to UTC can be found under any rock!


    NTP synchronizes computer clocks to a common time-base. This is usually
    UTC, but it does not have to be.

    The important thing is that you have a "stable tick". Otherwise you have
    clocks chasing a moving target.

    --
    Steve Kostecke
    NTP Public Services Project - http://ntp.isc.org/

  16. Re: Resolution and Precision

    mills@udel.edu wrote:
    > David,
    >
    > RFC 1305 was the seat of furious controversy. I consider the only
    > authorative document is in PostScript, later in PDF. The IETF and I
    > have engaged in serious disagreement on PDF formats as against Postel
    > ASCII. Everything, and I mean everything today is in PDF - Governent
    > documents and forms, University documents and forms, IEEE standards,
    > ACM and IEEE publications and everything else I do is in PDF. So,
    > what you see is what you get. The PDF of RFC 1305 is on the NTP
    > project page.
    > Dave


    Thanks, Dave.

    I see that reference 25 points to:
    Abstract:
    http://www.eecis.udel.edu/~mills/dat...5/rfc1305a.pdf
    Body: http://www.eecis.udel.edu/~mills/dat...5/rfc1305b.pdf
    Appendices:
    http://www.eecis.udel.edu/~mills/dat...5/rfc1305c.pdf

    On page 11 of the body, the word "precision" is used in the context where
    I would use "resolution". It isn't used in the sense of "how close to the
    correct time is this clock", which I might call accuracy. Perhaps it
    would be helpful to have these terms defined somewhere? Perhaps the terms
    are used differently by different cultures, even!

    Cheers,
    David



  17. Re: Resolution and Precision (was: Using ntpdate -b SERVER shortly after SERVER boots)

    Richard B. gilbert wrote:
    []
    > Dave Mills has a version, I think it's in PDF, that has page numbers.
    > Look under section 3.2.1, common variables.
    > http://www.eecis.udel.edu/~mills/database/rfc/rfc1305/


    Thanks, Richard. I already answered Dave's reply about this.

    David



  18. Re: Resolution and Precision

    I see Harlan has now pointed to the NTP definitions:

    http://ntp.isc.org/bin/view/Support/...tedDefinitions

    Thanks,
    David



  19. Re: Fwd: Using ntpdate -b SERVER shortly after SERVER boots

    Harlan Stenn wrote:
    >>>>In article <5o89a4-3sb.ln1@robert.houseofmax.de>, Uwe Klein writes:

    >
    >
    > Uwe> What about a glossary of terms used?
    >
    > http://ntp.isc.org/Support/NTPRelatedDefinitions
    >
    > H

    Hey, Thanks.
    No wishes remaining for Xmas.

    uwe

  20. Re: Using ntpdate -b SERVER shortly after SERVERboots

    Richard B. gilbert wrote:
    > Donald Murray, P.Eng. wrote:
    >> On 10 Feb 2007 02:16:02 GMT, Steve Kostecke wrote:
    >>
    >>> On 2007-02-08, Donald Murray, P.Eng. wrote:
    >>>
    >>>
    >>>> How quickly can an isolated ntp server respond to 'ntpdate' queries
    >>>> after the server starts?

    >
    >> I bet this sounds pretty awful to most of you. It sounds kind of awful
    >> to me as well.
    >>
    >> Thanks for your suggestions. I appreciate everyone taking the time to respond.
    >> Do I get a prize for most inappropriate use of ntp? ;-)

    >
    >
    > You have NO IDEA how fierce the competition for that prize is!!!!!
    >
    > I don't think we've seen anybody trying to NTP to drive nails or fix a
    > dripping faucet but sooner or later we'll get those too.


    Well using it as a thermometer is one of the more interesting usages...

    Danny
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    questions mailing list
    questions@lists.ntp.isc.org
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