Geographical diversity of Stratum 1 servers - NTP

This is a discussion on Geographical diversity of Stratum 1 servers - NTP ; Looking for a reference on geographical diversity of Stratum 1 servers (GPS appliances, in this case). We have two clocks now (an old Datum TymServ with a Symetricom sticker) and another unknown brand. We'd like to add a third at ...

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Thread: Geographical diversity of Stratum 1 servers

  1. Geographical diversity of Stratum 1 servers

    Looking for a reference on geographical diversity of Stratum 1 servers (GPS
    appliances, in this case). We have two clocks now (an old Datum TymServ
    with a Symetricom sticker) and another unknown brand. We'd like to add a
    third at a completely different facility a mile or more away.

    What, other than the business continuity angle can I use? I'm assuming it
    would be better to have the clocks separated from a GPS perspective, too.

    Cites?

    Thanks!!

    --
    Peter Laws / N5UWY
    National Weather Center / Network Operations Center
    University of Oklahoma Information Technology
    plaws@ou.edu
    -----------------------------------------------------------------------
    Feedback? Contact my director, Craig Cochell, craigc@ou.edu. Thank you!

  2. Re: Geographical diversity of Stratum 1 servers

    >>> In article <47B215BF.4020705@ou.edu>, plaws@ou.edu (Peter Laws) writes:

    Peter> Looking for a reference on geographical diversity of Stratum 1
    Peter> servers (GPS appliances, in this case). We have two clocks now (an
    Peter> old Datum TymServ with a Symetricom sticker) and another unknown
    Peter> brand. We'd like to add a third at a completely different facility a
    Peter> mile or more away.

    Peter> What, other than the business continuity angle can I use? I'm
    Peter> assuming it would be better to have the clocks separated from a GPS
    Peter> perspective, too.

    Peter,

    Please consider adding whatever information you come up with to:

    http://support.ntp.org/bin/view/Supp...eferenceClocks

    --
    Harlan Stenn
    http://ntpforum.isc.org - be a member!

  3. Starting ISC NTP -4.2.4


    Hi All

    Iam trying to install ISC NTP-4.2.4 on RHEL 4. But Im not able to start
    the services.

    I firstly removed the default rpm and then compiled the latest version,
    configured the ntp.conf file, but Iam not able to start the service. I
    give the command /etc/init.d/ntpd start. # prompt comes back.

    Can anyone guide me in figuring out and solving the problem

    Regards
    Vivek Aggarwal
    +91-9945505704

  4. Re: Starting ISC NTP -4.2.4


    >Iam trying to install ISC NTP-4.2.4 on RHEL 4. But Im not able to start
    >the services.


    >I firstly removed the default rpm and then compiled the latest version,
    >configured the ntp.conf file, but Iam not able to start the service. I
    >give the command /etc/init.d/ntpd start. # prompt comes back.


    >Can anyone guide me in figuring out and solving the problem


    Did you do a make install?

    Do you even have a file in /etc/init.d/ntpd? I expect the old
    one came from the rpm and it probably didn't get replaced by
    anything from the ntp source package - those things are too
    system specific.

    Did it give any error messages? They usually end up in
    /var/log/messages unless/until you switch them to another
    log file with a logfile command in your config file.

    /etc/init.d/ntpd is just a shell script. You should be able to
    debug it. (It might take a while if you haven't worked in that
    area before.) Use "echo xxx" as the printf equivalent. "echo $foo"
    will expand foo from the environment variables.

    --
    These are my opinions, not necessarily my employer's. I hate spam.


  5. Re: Starting ISC NTP -4.2.4

    Hi

    Thanks for the quick response. Yaa I did make install, even I copied the
    default startup script too, but its not working. I will check the log
    messages and check if its showing some errors

    Regards
    Vivek Aggarwal

    -----Original Message-----
    From: questions-bounces+q4997c=motorola.com@lists.ntp.org
    [mailto:questions-bounces+q4997c=motorola.com@lists.ntp.org] On Behalf
    Of Hal Murray
    Sent: Wednesday, February 13, 2008 1:41 PM
    To: questions@lists.ntp.org
    Subject: Re: Starting ISC NTP -4.2.4


    >Iam trying to install ISC NTP-4.2.4 on RHEL 4. But Im not able to start
    >the services.


    >I firstly removed the default rpm and then compiled the latest version,
    >configured the ntp.conf file, but Iam not able to start the service. I
    >give the command /etc/init.d/ntpd start. # prompt comes back.


    >Can anyone guide me in figuring out and solving the problem


    Did you do a make install?

    Do you even have a file in /etc/init.d/ntpd? I expect the old
    one came from the rpm and it probably didn't get replaced by
    anything from the ntp source package - those things are too
    system specific.

    Did it give any error messages? They usually end up in
    /var/log/messages unless/until you switch them to another
    log file with a logfile command in your config file.

    /etc/init.d/ntpd is just a shell script. You should be able to
    debug it. (It might take a while if you haven't worked in that
    area before.) Use "echo xxx" as the printf equivalent. "echo $foo"
    will expand foo from the environment variables.

    --
    These are my opinions, not necessarily my employer's. I hate spam.

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

  6. Re: Geographical diversity of Stratum 1 servers

    Peter Laws wrote:
    > Looking for a reference on geographical diversity of Stratum 1 servers
    > (GPS appliances, in this case). We have two clocks now (an old Datum
    > TymServ with a Symetricom sticker) and another unknown brand. We'd like
    > to add a third at a completely different facility a mile or more away.
    >
    > What, other than the business continuity angle can I use? I'm assuming
    > it would be better to have the clocks separated from a GPS perspective,
    > too.
    >
    > Cites?


    AFAIK geographical diversity does nothing to improve the time. It does
    add some robustness. If you are powered from different substations,
    good. Are the sites far enough apart to avoid being caught in the same
    flood, fire, earthquake, explosion, chemical/biological/radiologcal
    contamination, etc?

    There is something called "differential GPS" which can help refine
    position data; e.g. if you have GPS at both a known and an unknown
    location, the difference between readings can be used to refine the
    unknown position.

    The GPS computation of location, elevation, and time involves a system
    of four simultaneous equations which can be solved for time, lattitude,
    longitude, and elevation. Doing an extended "site survey" can refine
    your location and elevation. The better location data, the better the
    solution for time.


  7. Re: Starting ISC NTP -4.2.4

    On 2008-02-13, Aggarwal Vivek-Q4997C wrote:

    > Iam trying to install ISC NTP-4.2.4 on RHEL 4. But Im not able to start
    > the services.


    There is no such thing as ISC NTP.

    You are probably using the NTP Reference Implementation from
    www.ntp.org.

    > I firstly removed the default rpm and then compiled the latest version,
    > configured the ntp.conf file, but Iam not able to start the service. I
    > give the command /etc/init.d/ntpd start. # prompt comes back.


    ntpd is a daemon. So it does not produce output on the console.

    You have to look in your syslog for ntpd related messages or your ntp
    log (if you have that configured). Use 'ntpq -p' to see the peerstatus
    billboard for your ntpd.

    The current Distribution Documentation is linked from
    http://www.ntp.org/documentatation.html and http://support.ntp.org/doc

    Community Supported Documentation is available at
    http://support.ntp.org/support

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

  8. Re: Starting ISC NTP -4.2.4

    I've compiled some RPMs for RHEL/CentOS that are using the latest stable
    version of NTP... Or you can build your own from the SRC RPM...

    http://ntp.extremeoverclocking.com/rpm/


    Jason


    > Hi All
    >
    > Iam trying to install ISC NTP-4.2.4 on RHEL 4. But Im not able to start
    > the services.
    >
    > I firstly removed the default rpm and then compiled the latest version,
    > configured the ntp.conf file, but Iam not able to start the service. I
    > give the command /etc/init.d/ntpd start. # prompt comes back.
    >
    > Can anyone guide me in figuring out and solving the problem
    >
    > Regards
    > Vivek Aggarwal


  9. Re: Geographical diversity of Stratum 1 servers

    Are both your current clocks using the same GPS antenna? If so, there is a
    common point of failure right there.

    If you put a 3rd clock w/3rd antenna at a different location you can do some
    interesting measurements between the 3.

    GPS is going to give you the most accurate / stable time (assuming you don't
    have interference). WWVB & LORAN-C are alternatives to GPS... But unless
    your location prevents the use of GPS is would still be the preferred time
    source.

    If you ever want to get rid of the Tymserve, I'll take it!


    > Looking for a reference on geographical diversity of Stratum 1 servers

    (GPS
    > appliances, in this case). We have two clocks now (an old Datum TymServ
    > with a Symetricom sticker) and another unknown brand. We'd like to add a
    > third at a completely different facility a mile or more away.
    >
    > What, other than the business continuity angle can I use? I'm assuming it


    > would be better to have the clocks separated from a GPS perspective, too.


  10. Re: Geographical diversity of Stratum 1 servers

    > The GPS computation of location, elevation, and time involves a system
    > of four simultaneous equations which can be solved for time, lattitude,
    > longitude, and elevation. Doing an extended "site survey" can refine
    > your location and elevation. The better location data, the better the
    > solution for time.


    The Tymserve (assuming model 2100 since that was the last and most popular)
    does a site-survey on power-up. Unfortunately you can't manually input your
    location (if you know it is more accurate) but the TS2100 does a pretty good
    job. It also disciplines an oscillator from the 1PPS so that it can flywheel
    in holdover mode.

    Jason

  11. Re: Geographical diversity of Stratum 1 servers

    Jason Rabel wrote:
    >> The GPS computation of location, elevation, and time involves a system
    >> of four simultaneous equations which can be solved for time, lattitude,
    >> longitude, and elevation. Doing an extended "site survey" can refine
    >> your location and elevation. The better location data, the better the
    >> solution for time.

    >
    > The Tymserve (assuming model 2100 since that was the last and most popular)
    > does a site-survey on power-up. Unfortunately you can't manually input your
    > location (if you know it is more accurate) but the TS2100 does a pretty good
    > job. It also disciplines an oscillator from the 1PPS so that it can flywheel
    > in holdover mode.
    >
    > Jason

    You can enter the position manually. And program the receiver mode. I
    added a lot of access to the embedded trimble receiver. It's been a
    while so I don't remember the details but look in the command shell
    /timing/gps/util.

  12. Re: Starting NTP -4.2.4

    Aggarwal Vivek-Q4997C wrote:
    > Hi All
    >
    > Iam trying to install ISC NTP-4.2.4 on RHEL 4. But Im not able to start
    > the services.
    >


    You'd have a very hard time doing that since there is no ISC NTP. There
    is an NTP reference implementation from ntp.org.

    Danny

  13. Re: Geographical diversity of Stratum 1 servers

    Peter Laws wrote:
    > Looking for a reference on geographical diversity of Stratum 1 servers (GPS
    > appliances, in this case). We have two clocks now (an old Datum TymServ
    > with a Symetricom sticker) and another unknown brand. We'd like to add a
    > third at a completely different facility a mile or more away.
    >
    > What, other than the business continuity angle can I use? I'm assuming it
    > would be better to have the clocks separated from a GPS perspective, too.


    Thanks to all that helped with this, here and off-line. Turns out the
    Datum TymServe 2100 (yep, that old) wasn't as dead as believed.

    I've got it flashed to the last version of the fw and it's connected to an
    antenna in another building and it is still, to my knowledge, working (I
    forgot to get the port provisioned on the switch so I can't log in! :-D ).

    So, if it continues to function, it becomes the 3rd Stratum 1 server.

    A follow-up if I may - it doesn't appear that I can peer the 2100s together
    so my thinking is to have a group of Stratum 2s "around" the three Stratum
    1s. They are all peered together and point to the 3 Stratum 1s for their
    time. Everyone else then will point at the stratum 2s.

    Is there a better way to do this or will this work?

    --
    Peter Laws / N5UWY
    National Weather Center / Network Operations Center
    University of Oklahoma Information Technology
    plaws@ou.edu
    -----------------------------------------------------------------------
    Feedback? Contact my director, Craig Cochell, craigc@ou.edu. Thank you!

  14. Re: Geographical diversity of Stratum 1 servers

    Peter Laws wrote:
    > Peter Laws wrote:
    >
    >> Looking for a reference on geographical diversity of Stratum 1 servers
    >> (GPS
    >> appliances, in this case). We have two clocks now (an old Datum TymServ
    >> with a Symetricom sticker) and another unknown brand. We'd like to add a
    >> third at a completely different facility a mile or more away.
    >>
    >> What, other than the business continuity angle can I use? I'm
    >> assuming it
    >> would be better to have the clocks separated from a GPS perspective, too.

    >
    >
    > Thanks to all that helped with this, here and off-line. Turns out the
    > Datum TymServe 2100 (yep, that old) wasn't as dead as believed.
    >
    > I've got it flashed to the last version of the fw and it's connected to
    > an antenna in another building and it is still, to my knowledge, working
    > (I forgot to get the port provisioned on the switch so I can't log in!
    > :-D ).
    >
    > So, if it continues to function, it becomes the 3rd Stratum 1 server.
    >
    > A follow-up if I may - it doesn't appear that I can peer the 2100s
    > together so my thinking is to have a group of Stratum 2s "around" the
    > three Stratum 1s. They are all peered together and point to the 3
    > Stratum 1s for their time. Everyone else then will point at the stratum
    > 2s.
    >
    > Is there a better way to do this or will this work?
    >


    Depending on the number of clients you need to support, you might not
    need a layer of stratum two servers. If it's possible to configure this
    box to use broadcast mode, you could simply tell it to broadcast a "time
    hack" to your network every 64 seconds or whatever interval you find
    works best. As each client initializes, it will query the server to get
    the round trip delay, crypto keys, etc. Once the client has done its
    initial hand shaking, it will just sit there and listen. It's generally
    possible for an NTP server to support several hundred or even several
    thousand clients.


  15. Re: Geographical diversity of Stratum 1 servers

    Richard B. Gilbert wrote:

    > Depending on the number of clients you need to support, you might not
    > need a layer of stratum two servers. If it's possible to configure this
    > box to use broadcast mode, you could simply tell it to broadcast a "time


    Well, ideally every system on campus, which is probably well over 10,000
    aggregate, but I only really care about servers. Even of those, probably
    less than 20 or so need *really* accurate time.

    Right now, almost everything is pointed at one of the Stratum 1 servers.
    Not very robust should that die.

    Broadcast/multicast? Probably not as we'll be moving the appliances to an
    administrative network at some point. Could do multicast from the Stratum
    2 systems, though.


    --
    Peter Laws / N5UWY
    National Weather Center / Network Operations Center
    University of Oklahoma Information Technology
    plaws@ou.edu
    -----------------------------------------------------------------------
    Feedback? Contact my director, Craig Cochell, craigc@ou.edu. Thank you!

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