[ntp:questions] Synchronize clocks without a reference clock

Per Hedeland per at hedeland.org
Fri Mar 30 19:36:51 UTC 2007


In article <slrnf0qap9.i0h.kostecke at stasis.kostecke.net> Steve Kostecke
<kostecke at ntp.isc.org> writes:
>On 2007-03-26, Per Hedeland <per at hedeland.org> wrote:
>
>> "Maarten Wiltink" <maarten at kittensandcats.net> writes:
>>
>>> [With orphan mode] You're still picking a single clock to follow,
>>>only now it's a random one.
>>
>> I guess this is correct for the current implementation, though there
>> ought to be a potential for an "intelligent" selection - e.g. taking
>> the drift value into consideration to reduce the risk of this problem:
>
>How can you measure drift without an accurate reference (e.g. a
>timebase) ?

Well, I was mainly thinking of the case where you have orphan mode set
up as a fallback to external servers - then the drift value that has
been calculated while external servers were reachable is a good "quality
indicator". But I assume the non-"masters" in an orphan-only setup
calculate a drift relative to the "master" - in that case, if you're
happy with the drift of the "master", you will be least unhappy if the
host with the lowest drift relative to the departed "master" is chosen
as the new "master".

--Per Hedeland
per at hedeland.org




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