Motorola Canopy CMM as NTP server - NTP

This is a discussion on Motorola Canopy CMM as NTP server - NTP ; Hello! Motorola Canopy is wireless networking system. Up to six Canopy sector access points (AP) can be used together as cluster managed by CMM (Cluster Management Module). CMM contains GPS receiver which is used to synchronize multiple transmitters. CMM has ...

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Thread: Motorola Canopy CMM as NTP server

  1. Motorola Canopy CMM as NTP server

    Hello!

    Motorola Canopy is wireless networking system. Up to six Canopy
    sector access points (AP) can be used together as cluster
    managed by CMM (Cluster Management Module). CMM contains GPS
    receiver which is used to synchronize multiple transmitters. CMM
    has IP address and NTP server running on port 123. The server
    reports itself as Stratum-1.

    Some people use CMM as primary time source of their networks. I
    have tried this too. But my ntpd quickly "disqualified"
    those "Stratum-1" units and reverted to Stratum-2 servers! ntpq
    showed that CMM units had unacceptable jitter values (hundreds
    of milliseconds).

    Packet sniffer showed that Canopy CMM always reports time
    rounded to integer number of seconds. This is the problem. CMM
    has very accurate GPS time inside it but reports only seconds
    through NTP. I am unsure is it bug or "feature".

    I have requested feedback from Motorola. For now, do not use
    Canopy CMM as NTP server for anything but Canopy equipment.

    Dmitry.
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  2. Motorola Canopy CMM as NTP server

    In article <200609291235.38183.dimss@telecentrs.lv>,
    dimss@telecentrs.lv (Dmitry Ivanov) wrote:

    > Packet sniffer showed that Canopy CMM always reports time
    > rounded to integer number of seconds. This is the problem. CMM
    > has very accurate GPS time inside it but reports only seconds
    > through NTP. I am unsure is it bug or "feature".


    It's a bug if it doesn't also report a precision of 0. If it does
    report a precision of zero, I would have thought it would have used
    all of its allowed error budget on that one term, so would be very
    difficult to select.


  3. Re: Motorola Canopy CMM as NTP server

    On Monday 02 October 2006 09:28, David Woolley wrote:
    > It's a bug if it doesn't also report a precision of 0. If it
    > does report a precision of zero, I would have thought it would
    > have used all of its allowed error budget on that one term, so
    > would be very difficult to select.


    Thank you, David! Apparently, CMM reports precision of 2 secs:

    ------------------------------------------------------------

    User Datagram Protocol, Src Port: ntp (123), Dst Port: 33388
    (33388)
    Network Time Protocol
    Flags: 0x12
    Peer Clock Stratum: primary reference (1)
    Peer Polling Interval: invalid (0)
    Peer Clock Precision: 2.000000 sec
    Root Delay: 0.0000 sec
    Clock Dispersion: 0.0000 sec
    Reference Clock ID: Global Positioning Service
    Reference Clock Update Time: Oct 2, 2006 08:36:34.0000 UTC
    Originate Time Stamp: NULL
    Receive Time Stamp: Oct 2, 2006 08:36:34.0000 UTC
    Transmit Time Stamp: Oct 2, 2006 08:36:34.0000 UTC
    Key ID: 00000000
    Message Authentication Code: 00000000000000000000000000000000
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