Ntp in peer configuration - NTP

This is a discussion on Ntp in peer configuration - NTP ; Hi, I am trying to use NTP in peer configuration. The requirements: 1. The machines on the network can start up at different times. 2. The machines that have come up at a later time than the 1st one, would ...

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Thread: Ntp in peer configuration

  1. Ntp in peer configuration

    Hi,
    I am trying to use NTP in peer configuration.

    The requirements:
    1. The machines on the network can start up at different times.
    2. The machines that have come up at a later time than the 1st one, would perform an ntpdate so as to have a correct notion of time quickly.
    3. The case of multiple machines coming up at the same time should be handled
    4. At no point in time should there be multiple NTP servers thus forming two different clock domains.
    5. All machines on the network should have a common notion of time (offset not larger than 20ms) - not necessarily the 'correct' time(no need of getting time from external servers)

    My Observations:
    If a device that comes up at a later point in time than the 1st does an ntpdate with the 1st, ntpdate fails as the 1st one is not "locked" to any server.

    So, to solve the above, I configured the 1st machine on the network with reference clock as LOCL. So, when the 2nd device comes up, ntpdate is successful. However, this introduces additional complexity like: 2 devices coming up at the same time and both going for LOCL clocks and then I need to detect and resolve it. Also, it might happen that some devices lock to another NTP server other than the one with LOCL, thus, giving rise to mutiple NTP servers.

    Any suggestions/pointers are welcome!

    Regards,
    Ginnie


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  2. Re: Ntp in peer configuration

    On 2008-04-09, Ginni Misra wrote:

    > I am trying to use NTP in peer configuration.


    In a time island.

    > 5. All machines on the network should have a common notion of time
    > (offset not larger than 20ms) - not necessarily the 'correct' time(no
    > need of getting time from external servers)


    NTP synchronizes clocks to a _common_ _time_ _base_. The time base that
    is customarily used is UTC. UTC is ubiquitous (e.g. available via the
    Internet, GPS, GPS over CMDA, HF Radio, ATCS dialup) and is relatively
    inexpensive compared to the cost of generating a local time base of
    similar stability.

    >So, to solve the above, I configured the 1st machine on the network
    >with reference clock as LOCL. So, when the 2nd device comes up, ntpdate
    >is successful. However, this introduces additional complexity like: 2


    You're doing this the hard way.

    An "Orphan mesh" (or web) is the preferred way to handle your situation;
    assuming that you are using NTP 4.2.x.

    Orphan mode is enabled by adding the following line to the ntp.conf of
    all of your systems:

    tos orphan 5

    Then you need to choose the mode for your mesh: unicast, broadcast, or
    multicast. Each system in the mesh needs to be configured to poll all of
    the other systems.

    You may wish to consult the following news-group articles for
    configuration information:

    https://lists.ntp.org/pipermail/hack...ch/002809.html
    http://www.mail-archive.com/question.../msg00986.html

    Those articles do not address setting up a unicast (conventional
    client/server) mesh. If you just have a small number of systems this may
    be the the easiest solution as it avoids configuring NTP authentication.

    Each system in a 4 node mesh could have an ntp.conf which looks like
    this:

    -----------------------------------8X-----------------------------------

    driftfile /path/to/drift.file
    tos orphan 5
    server A iburst
    server B iburst
    server C iburst
    server D iburst

    -----------------------------------8X-----------------------------------

    Make sure that ntpd is started with '-g' so that the initial time can
    make an unlimited step.

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

  3. Re: Ntp in peer configuration

    Ginni Misra wrote:
    > I am trying to use NTP in peer configuration.


    No. You are trying to use NTP in an orphaned configuration, which has
    never had any parents! NTP was not designed for that, although recent
    additions (ophan mode) make it just about workable.

    Timed was designed for that, so you should be investigating that.

    PS. Please restrict your lines to about 70 characters or use a user
    agent that that specifies format=flowed (these will automatically
    restrict the lengths of the lines, but a compatible user agent will
    merge and re-wrap then appropriately).


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