[ntp:questions] synchronization distance
David Woolley
david at ex.djwhome.demon.invalid
Sat Dec 4 19:10:42 UTC 2010
David L. Mills wrote:
> David,
>
> I'm not making myself absolutely crystal clear and you are obscuring the
> point.
>
> Windows has an awesome protocol that sets the time. It happens to use
> the NTP packet header format, but is not otherwise compliant with the
> NTPv4 specification, especially the 36-h poll interval limitation, which
> is an engineering parameter based on the expected wander of a commodity
> crystal oscillator. All that doesn't matter at all, other than Windows
> servers are compatible with Windows clients. What does matter is that
> Windows servers are NOT compatible with NTPv4 clients, which SHOULD NOT
> BE USED. Use one of the SNTP variants instead.
To a large extent I would agree with you, but the net effect of this is
to say "if you work for a marketing led company (probably true of most
of the Fortune 500), do not use NTP as it is almost certain that your IT
department has a strict Microsoft policy for their core systems, and are
not time synchronisation experts".
>
> As a diehard workaround, use the tos maxdist command to set the distance
> threshold to something really high, like ten seconds. There is nothing
> whatsoever to be gained by this, as the expected error with update
> intervals of a week will be as bad or worse than with SNTP..
>
> Dave
>
> David Woolley wrote:
>
>> David L. Mills wrote:
>>
>>> BlackList,
>>>
>>> I say again with considerable emphasis: this is a Microsoft product,
>>> not the NTPv4 distribution that leaves here. What you see is what you
>>> get,
>>
>>
>> But it is often NTPv4 reference version that is used as the client and
>> fails to synchronize because the root dispersion is too high.
>>
>> Corporate politics are such that it is difficult to get a Unix system,
>> or even Windows running the reference version, near the root of the
>> time distribution tree. People deeper in the tree then see the
>> effects, even if they are using the reference implementation.
>>
>>> warts and all. I doubt it has anything to do with root distance, or
>>> any other public specification, but that doesn't make any difference
>>> if the customer is satisfied with the performance. Just don't compare
>>> it with anything in the NTP distribution, documentation or
>>> specification.
>>>
>>> Dave
>>>
>>> E-Mail Sent to this address will be added to the BlackLists wrote:
>>>
>>>> David L. Mills wrote:
>>>>
>>>>
>>>>> I had no idea somebody would try to configure current
>>>>> NTPv4 with a poll interval of a week.
>>>>> The current maximum allowed is 36 h.
>>>>>
>>>>
>>>>
>>>> <http://technet.microsoft.com/en-us/library/cc773263%28WS.10%29.aspx>
>>>> <BlockQuote>
>>>> SpecialPollInterval
>>>> This entry specifies the special poll interval in seconds
>>>> for manual peers. ...
>>>> The default value on stand-alone clients and servers is 604,800.
>>>> </BlockQuote>
>>>>
>>>> {7 days}
>>>>
>>>>
>>>>
>>>>
>>
>> _______________________________________________
>> questions mailing list
>> questions at lists.ntp.org
>> http://lists.ntp.org/listinfo/questions
More information about the questions
mailing list