Do we need / should be have a refclock? - NTP

This is a discussion on Do we need / should be have a refclock? - NTP ; Hi, I'm fairly new to NTP (although I have read a lot of the documentation on the site and in the wiki) and I'm trying to get some expert advice to help with an internal IT discussion occurring in the ...

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Thread: Do we need / should be have a refclock?

  1. Do we need / should be have a refclock?

    Hi,

    I'm fairly new to NTP (although I have read a lot of the documentation
    on the site and in the wiki) and I'm trying to get some expert advice to
    help with an internal IT discussion occurring in the IT team at my
    company.

    We have about 20-30 linux servers collocated (on two sites - 95% of them
    on one site) and about 30 windows desktops at a different site. The new
    Linux sysadmin has noticed that the NTP client configuration on the
    servers is fairly random (they seem to use various random UK ISP's NTP
    servers (only one NTP server configured for each box)). Clearly that
    needs sorting out - but in the course of the discussion there was a
    debate about whether we ought to get a refclock.

    Could you give some advice on how we should be thinking about this, what
    we should consider, and what the pros and cons of using a refclock are.

    For reference we basically do web hosting for our clients on these
    servers - some run databases and so on but there is nothing particularly
    unusual that the servers do.

    If you think a refclock is a good idea or an important thing to have the
    one that has been suggested is this one
    http://www.atomic-clock.galleon.eu.c...erver/Atomic-C
    lock-Time-Server.htm

    If on the other hand there is a simple place I can RTFM then please
    point me to it :-)

    Robert Hulme
    Technical Consultant
    Anthony Hodges Consulting Limited

    Direct line: (01924) 203904
    Switchboard: (01924) 203900
    Email: Robert.Hulme@ahc.uk.com

    _______________________________________________
    questions mailing list
    questions@lists.ntp.isc.org
    https://lists.ntp.isc.org/mailman/listinfo/questions


  2. Re: Do we need / should be have a refclock?

    Robert Hulme wrote:
    > Hi,
    >
    > I'm fairly new to NTP (although I have read a lot of the documentation
    > on the site and in the wiki) and I'm trying to get some expert advice
    > to help with an internal IT discussion occurring in the IT team at my
    > company.
    >
    > We have about 20-30 linux servers collocated (on two sites - 95% of
    > them on one site) and about 30 windows desktops at a different site.
    > The new Linux sysadmin has noticed that the NTP client configuration
    > on the servers is fairly random (they seem to use various random UK
    > ISP's NTP servers (only one NTP server configured for each box)).
    > Clearly that needs sorting out - but in the course of the discussion
    > there was a debate about whether we ought to get a refclock.
    >
    > Could you give some advice on how we should be thinking about this,
    > what we should consider, and what the pros and cons of using a
    > refclock are.
    >
    > For reference we basically do web hosting for our clients on these
    > servers - some run databases and so on but there is nothing
    > particularly unusual that the servers do.
    >
    > If you think a refclock is a good idea or an important thing to have
    > the one that has been suggested is this one
    > http://www.atomic-clock.galleon.eu.c...erver/Atomic-C
    > lock-Time-Server.htm
    >
    > If on the other hand there is a simple place I can RTFM then please
    > point me to it :-)
    >
    > Robert Hulme


    Robert,

    My broad view would be that if you are providing services for others then
    either:

    - you should have multiple physical connections to the Internet

    or

    - you should have your own stratum 1 server.

    I rate a stratum 1 server as "desirable" rather than "essential". If you
    have some in-house electronics experience making a stratum one server can
    be very simple, for example:

    http://www.david-taylor.myby.co.uk/n...SD-GPS-PPS.htm

    I would then recommend that you adopt a two-tier hierarchy for your NTP
    infrastructure, with some local servers talking to several Internet
    servers (and your own stratum 1 server if you get one), and the rest of
    the kit talking just to those local servers. How exactly you spilt this
    depends (I think) on the connectivity between the sites themselves and
    between the sites and the Internet.

    Cheers,
    David



  3. Re: Do we need / should be have a refclock?

    Robert Hulme wrote:

    > Hi,
    >
    > I'm fairly new to NTP (although I have read a lot of the documentation
    > on the site and in the wiki) and I'm trying to get some expert advice to
    > help with an internal IT discussion occurring in the IT team at my
    > company.
    >
    > We have about 20-30 linux servers collocated (on two sites - 95% of them
    > on one site) and about 30 windows desktops at a different site. The new
    > Linux sysadmin has noticed that the NTP client configuration on the
    > servers is fairly random (they seem to use various random UK ISP's NTP
    > servers (only one NTP server configured for each box)). Clearly that
    > needs sorting out - but in the course of the discussion there was a
    > debate about whether we ought to get a refclock.
    >
    > Could you give some advice on how we should be thinking about this, what
    > we should consider, and what the pros and cons of using a refclock are.
    >
    > For reference we basically do web hosting for our clients on these
    > servers - some run databases and so on but there is nothing particularly
    > unusual that the servers do.
    >
    > If you think a refclock is a good idea or an important thing to have the
    > one that has been suggested is this one
    > http://www.atomic-clock.galleon.eu.c...erver/Atomic-C
    > lock-Time-Server.htm
    >
    > If on the other hand there is a simple place I can RTFM then please
    > point me to it :-)
    >
    > Robert Hulme
    > Technical Consultant
    > Anthony Hodges Consulting Limited
    >
    > Direct line: (01924) 203904
    > Switchboard: (01924) 203900
    > Email: Robert.Hulme@ahc.uk.com
    >
    > _______________________________________________
    > questions mailing list
    > questions@lists.ntp.isc.org
    > https://lists.ntp.isc.org/mailman/listinfo/questions
    >


    You really need to define your requirements. When you have specified
    the accuracy you need and the reliability you need, we can probably give
    better advice. If traceability of your timestamps to a national
    standards lab is a requirement be sure to mention that as well


    A refclock, particularly a GPS timing receiver, provides an ultra stable
    and ultra accurate reference. The stability means that clients can
    synchronize with the server synchronized to that refclock and stay
    within, say, 50 microseconds of it. A great deal depends on the
    hardware and O/S being used. A refclock can, but need not, be
    expensive; mine cost me $200 US. The cheapest I know of is about $85 US.

    The fast, easy, and cheap solution, is to designate one of those Linux
    boxes as your house timeserver and configure it to use four or five
    internet servers. Then tell all the other boxes to synchronize with it.
    You can expect everybody to stay within ten to twenty milliseconds of UTC.

    If you need better reliability than a single in house server can
    provide, you can use more. That is a good reason to define your
    requirements up front.

  4. Re: Do we need / should be have a refclock?

    On Thu, 6 Jul 2006 09:09:55 GMT in comp.protocols.time.ntp,
    robert.hulme@ahc.uk.com (Robert Hulme) wrote:

    >Hi,
    >
    >I'm fairly new to NTP (although I have read a lot of the documentation
    >on the site and in the wiki) and I'm trying to get some expert advice to
    >help with an internal IT discussion occurring in the IT team at my
    >company.
    >
    >We have about 20-30 linux servers collocated (on two sites - 95% of them
    >on one site) and about 30 windows desktops at a different site. The new
    >Linux sysadmin has noticed that the NTP client configuration on the
    >servers is fairly random (they seem to use various random UK ISP's NTP
    >servers (only one NTP server configured for each box)). Clearly that
    >needs sorting out - but in the course of the discussion there was a
    >debate about whether we ought to get a refclock.
    >
    >Could you give some advice on how we should be thinking about this, what
    >we should consider, and what the pros and cons of using a refclock are.
    >
    >For reference we basically do web hosting for our clients on these
    >servers - some run databases and so on but there is nothing particularly
    >unusual that the servers do.
    >
    >If you think a refclock is a good idea or an important thing to have the
    >one that has been suggested is this one
    >http://www.atomic-clock.galleon.eu.c...erver/Atomic-C
    >lock-Time-Server.htm
    >
    >If on the other hand there is a simple place I can RTFM then please
    >point me to it :-)


    Check the web and wiki pages, but if you're not serving time to others
    and don't need high accuracy, but just want correct time and
    consistency netween your own systems, you probably don't need a
    refclock.

    If you have a lightly loaded Linux server at each of your sites, you
    could set up a couple of time servers, each referenced to at least
    four stratum 2 NTP servers close to them on the internet, with a
    couple of UK NTP pool servers as backups in case one of more of the
    stratum 2 servers go down.

    The other Linux servers at each site can then be set up as NTP clients
    to your two NTP servers, with a few UK NTP pool servers as backups in
    case your internal servers go down.

    The Windows machines can be set up as SNTP clients to your two NTP
    servers using built in Windows internet time facilities.

    --
    Thanks. Take care, Brian Inglis Calgary, Alberta, Canada

    Brian.Inglis@CSi.com (Brian[dot]Inglis{at}SystematicSW[dot]ab[dot]ca)
    fake address use address above to reply

  5. Re: Do we need / should be have a refclock?

    Brian Inglis wrote:
    []
    > The Windows machines can be set up as SNTP clients to your two NTP
    > servers using built in Windows internet time facilities.


    ... or you can run "real" NTP on Windows as well using, for example, the
    Meinberg build:

    http://www.meinberg.de/english/sw/ntp.htm

    and have the benefits of better timekeeping performance, and the ability
    to monitor remotely.

    David



  6. Re: Do we need / should be have a refclock?

    On Sun, 09 Jul 2006 17:48:58 GMT in comp.protocols.time.ntp, "David J
    Taylor"
    wrote:

    >Brian Inglis wrote:
    >[]
    >> The Windows machines can be set up as SNTP clients to your two NTP
    >> servers using built in Windows internet time facilities.

    >
    >.. or you can run "real" NTP on Windows as well using, for example, the
    >Meinberg build:
    >
    > http://www.meinberg.de/english/sw/ntp.htm
    >
    >and have the benefits of better timekeeping performance, and the ability
    >to monitor remotely.


    Had the OP said Windows servers, I'd agree, but he mentioned only
    desktops, for which NTP is overkill IMHO.

    --
    Thanks. Take care, Brian Inglis Calgary, Alberta, Canada

    Brian.Inglis@CSi.com (Brian[dot]Inglis{at}SystematicSW[dot]ab[dot]ca)
    fake address use address above to reply

  7. Re: Do we need / should be have a refclock?

    Brian Inglis wrote:
    > On Sun, 09 Jul 2006 17:48:58 GMT in comp.protocols.time.ntp, "David J
    > Taylor"
    > wrote:
    >
    >> Brian Inglis wrote:
    >> []
    >>> The Windows machines can be set up as SNTP clients to your two NTP
    >>> servers using built in Windows internet time facilities.

    >>
    >> .. or you can run "real" NTP on Windows as well using, for example,
    >> the Meinberg build:
    >>
    >> http://www.meinberg.de/english/sw/ntp.htm
    >>
    >> and have the benefits of better timekeeping performance, and the
    >> ability to monitor remotely.

    >
    > Had the OP said Windows servers, I'd agree, but he mentioned only
    > desktops, for which NTP is overkill IMHO.


    Possibly, but for me the advantage of having just one software type to
    manage (i.e. ntp alone rather than mixed ntp and Microsoft SNTP) would
    outweigh having to install NTP on the desktops. Swings and roundabouts!

    David



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