[ntp:questions] Tricking NTP's driftfile

David L. Mills mills at udel.edu
Wed Jun 25 14:32:57 UTC 2008


In the current development version reference clocks are reachable on the 
first poll. The preferred orphan mode is available intantly. The releasr 
version tends to lag the development version by some time; however, the 
design where refclocks are reachable on the first poll has been active 
for quite some time.


Steve Kostecke wrote:
> On 2008-06-24, David J Taylor <david-taylor at blueyonder.co.uk> wrote:
>>Steven wrote:
>>>While the master goes through its synchronization routine (~10 mins),
>>>the slaves cannot obtain the time (see below). Even after the master
>>>is responsive, the drift file is not written to.
>>Why does the master take that long?
> Using the current stable release of NTP (4.2.4) the Undisciplined Local
> Clock syncs after 4 "polls". The first "poll" occurs shortly after ntpd
> starts; let's say at ~ 10 seconds. The next three polls occur at
> minpoll. So with the default poll of 64 seconds ntpd needs:
> 10+(3*64) or ~ 202 seconds or ~ 3 min 22 seconds to declare the
> Undisciplined Local Clock to be "synced".
> If minpoll is reduced to 16 seconds (minpoll 4) the Undisciplined Local
> CLock "sync time" is:
> 10+(3*10) or ~ 40 seconds
> IIRC recent NTP-dev releases now immediately "sync" to the Undisciplined
> Local Clock at startup.

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