NTP sync on a standalone network (Windows 2k) - NTP

This is a discussion on NTP sync on a standalone network (Windows 2k) - NTP ; Alexandre Carrausse wrote: > > I have used the tool NTPmonitor V5.0.6.28 - from David Taylor and I can > confirm that everything is synchronised, so at least my main goal is > reached. > If you think there is ...

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Thread: NTP sync on a standalone network (Windows 2k)

  1. Re: NTP sync on a standalone network (Windows 2k)

    Alexandre Carrausse wrote:
    >
    > I have used the tool NTPmonitor V5.0.6.28 - from David Taylor and I can
    > confirm that everything is synchronised, so at least my main goal is
    > reached.
    > If you think there is more I could do (within my constraints), I am open to
    > learn.
    >


    Meinberg also has a pretty good tool for monitoring and can look at
    multiple systems.

    >>> But providing the fact that the remote clients will sync with the main
    >>> time server at the central site, over a 64 kbps network, is it reliable?
    >>>

    >> It's your net network! You should be in a far better position than I to
    >> say if it's reliable or not. You also need to specify what degree of
    >> reliability you need. If you cannot afford the failure of a network, you
    >> need redundant network connections
    >>

    >
    > Let me ask the question in a different way : is the NTP protocol running
    > without any problem over a 64 kbps, or is there any configuration to think
    > about, that would tell the remote "hold on mate, don't be too impatient
    > because I am sending my packets over a 64 kbps line". I have seen somewhere
    > that it could be necessary to implement the huff'n'puff option. Is it true?
    >


    It should. NTP was originally designed in the days when networks were
    not only unreliable but also over slow, by today's standards, networks.
    You also have a closed environment so the worst you will likely get is a
    switch outage or similar.

    >>

    > In fact my application which is based on clusters of servers, is running
    > over DCE Encina (IBM). In order to run, the servers must be very well
    > synchronised between them, and the time difference must never exceed 180 s.
    > If the time diff exceeds the threshold, everything will crash and will be
    > corrupted....
    >
    > I agree that my solution is not acurate, but it is quite stable (based on
    > the spec above), and for the reliability, I may have not to rely only on
    > one time server, but several...
    >


    Yes, DCE needs time accuracy, but only relative to the other nodes so I
    don't think that's a real concern.

    > OK. So it means that if someone change the time on the main server (+/-1000s
    > ie approx 20 mins) the NTP daemon will stop to provide time, and all the
    > machine on the network will start to drift appart?... until someone realise
    > that the NTPDaemon is not started.
    >


    If someone does that on the main server then the leaf nodes are likely
    to decide that it's crazy and not take time from it. Be warned however
    that if it's really acting as a domain controller, those nodes will be
    unable to verify things like passwords. As usual a domain controller
    needs to be secured against unauthorized access and in a secure
    environment like yours should be standard procedure.

    Because of your environment I wouldn't bother with all of these schemes
    to synchronize one system to the outside world. Just go with the scheme
    you already have in place, though do consider upgrading your ntpd
    software if you can.

    Danny
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  2. Re: NTP sync on a standalone network (Windows 2k)

    David Woolley wrote:
    > In article <44e63895$0$32471$626a54ce@news.free.fr>,
    > Alexandre Carrausse wrote:
    >> "Hal Murray" wrote in message
    >> news:_L2dnc1lD-lW5HjZnZ2dnUVZ_v6dnZ2d@megapath.net...
    >>> Using a single system as the master seems like a reasonable approach
    >>> to me. It's simple so you can understand it. Just fixup the time

    >
    > Definitely. Peering was never intended to be use for unsychronised
    > networks. It was not designed for creating a consensus time out of
    > nothing. For a start, local clocks are normally clocks of last
    > resort, so you would have to prefer them, but even then, the whole
    > system would almost certainly wander in frequency and could end up
    > with some machines exceeding the 500ppm maximum correctable frequency
    > offset.
    >


    Dave's new schemes allow this to work very well. It requires manycasting
    but it also needs the newer code.

    > Assuming that the NT port supports remote configuration, I would suggest
    > enabling that when you first stop the master server. You can then fudge
    > the correction, to trim the frequency, without having to stop the server
    > again.
    >


    I does in the same way as Unix versions but that's going away in the future.

    Danny
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  3. Re: NTP sync on a standalone network (Windows 2k)


    >>> adjtimex is the utility to tweak the clock frequency.

    >>
    >> Seems interesting in the long run.
    >> The only data I have found looks like code to be compiled for Unix. Anything
    >> ready for Windows?
    >>

    >
    >No, we've never had an occasion to build it. I don't think it's
    >necessary if you are running ntpd and just synching to the master.


    The idea was to tweak the local clock parameters so that it didn't drift much.

    You can do that by editing the drift file and restarting ntpd.

    I think my suggestion of adjtimex was probably a wild goose chase.

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  4. Re: NTP sync on a standalone network (Windows 2k)

    Hi Alex,


    Alexandre Carrausse schrieb:
    > "Wolfgang S. Rupprecht"
    > wrote in
    > message news:87mza1zqnv.fsf@bonnet.wsrcc.com...
    >> If you are allowed to have fiber-optical signals go into the room (but
    >> not out) you might be able to run a GPS in some not quite so secure
    >> area and send only the NMEA and/or PPS into the secure area.

    >
    > I agree but the link between the GPS antenna and the secure area will be
    > coper, not fiber.
    >
    > Are you aware of a GPS solution that would use fiber?


    Just take a look at this:
    http://www.meinberg.de/english/products/goal.htm

    You can use it with out LANTIME/GPS time servers for example. Or hook up
    one of our GPS receivers and connect that to one of your servers.
    Another possibility would be to use a Meinberg PCI card in your master
    server.

    The GOAL system can be combined with any Meinberg GPS receiver, examples
    are:
    http://www.meinberg.de/english/products/lantime.htm
    http://www.meinberg.de/english/products/gps167.htm
    http://www.meinberg.de/english/products/gps170pci.htm

    Best regards,
    Heiko


    >
    >
    >
    >
    >
    >
    >
    >
    >
    >
    >> -wolfgang
    >> --
    >> Wolfgang S. Rupprecht http://www.wsrcc.com/wolfgang/

    >
    >



    --
    Meinberg radio clocks: 25 years of accurate time worldwide

    MEINBERG Radio Clocks
    www.meinberg.de

    Stand alone ntp time servers and radio clocks based on GPS, DCF77 and
    IRIG. Rackmount and desktop versions and PCI slot cards.

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