[ntp:questions] Client using Meinberg NTP can't sync with ntp server problem

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Thu Jul 10 13:22:23 UTC 2014


On 2014-07-10 02:24, vothanhhung22 at gmail.com wrote:
> On Thursday, July 10, 2014 10:49:55 AM UTC+7, William Unruh wrote:
>> On 2014-07-10, vothanhhung22 at gmail.com <vothanhhung22 at gmail.com> wrote:
>>> On Thursday, July 10, 2014 3:53:42 AM UTC+7, David Woolley wrote:
>>>> On 09/07/14 18:30, E-Mail Sent to this address will be added to the
>>>> BlackLists wrote:
>>>>> vothanhhung22 at gmail.com wrote:
>>>>>>        remote           refid      st t when poll reach   delay   offset  jitter
>>>>>> ==============================================================================
>>>>>> *218.189.210.3   137.189.4.10     2 u    -  512   17   30.634  -46.455  23.503
>>>>> --^ It is synced !
>>>>>> associd=0 status=0615 leap_none, sync_ntp, 1 event, clock_sync,
>>>>> -----------------------------------^^^^^^^^-----------^^^^^^^^^^
>>>>>    It is synced !
>>>>> What makes you think it can't sync?
>>>>>    When clearly it is.
>>>> +1 (I make that 3 in total).
>>>> Also this isn't Meinberg's ntpd, it is the reference ntpd.  Only the
>>>> installer is from Meinberg.
>>> Hi all,
>>> After 2 hours it can sync now but I would expect it sync every 15 minutes because my program need precision time.
>> You have no idea how ntpd works do you? ntpd gets the time from its
>> servers. It then adjusts the rate of your clock in order to bring its
>> time in line with those remote clocks. eventually ( 1-10 hrs) its rate
>> will be the same as the remote rate, and its time will be the same as
>> the remote time. Thereafter it will slowly adjust things to stay in
>> sync.
>>
>> Your time will be within somewhere between 10 usec and 10ms of UTC once
>> everything settles down. What does "my program needs precision time"
>> mean? Within 1 pico second of UTC? wihin 10 sec of UTC?
> Thanks for your explaination. The reason I use NTP because I want my computer
> clock have the same time as the server. It is always 1 or 2 minutes behind
> compare to the ntp server. That's why I need it to sync the display time
> every 10 minutes.
> But as you said "nothing should happen before about an hour from when you started."
> means there is nothing I can do to "force" it sync every 10 minutes?

You can start ntpd with -g option which allows it to step your system time once,
when it first starts; using iburst "pool hk.ntp.pool.org iburst" will allow the
correct offset to be set within about 16s after startup. Thereafter it will stay
within +/-128ms of UTC; after it has settled, that should be about +/-10ms off UTC.
As another poster said, adding "pool asia.ntp.pool.org iburst" may improve your
offset.
Once it gets to long poll intervals, it actually improves the drift compensation
more, and reduces the offset further.
-- 
Take care. Thanks, Brian Inglis


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