[ntp:questions] strange ntpd behaviour when modyfing stratum

Grzegorz Daniluk lin_g at o2.pl
Fri Aug 22 14:40:39 UTC 2008

Hi all,
I'm running ntp-4.2.4p4 on FreeBSD.
I was observing today the ntpd with ntpq and manipulating the stratum 
number of local time sources in ntp.conf.
I've noticed that when I've disabled all pps sources and worked only 
with two gps antennas (receiving to ntp nmea frames only, ignoring pps, 
I set stratum 8 for antenna0 and stratum 12 for antenna1) the ntp has 
chosen antenna0 (so the source with higher stratum) and that's what I've 
But then I've set all the sources in ntp.conf (gps nmea and pps, ocxo 
pps, rubidium pps) and put stratum 12 option near one of them and 
stratum 8 near the others. I saw that ntp has chosen the pps source that 
had the lower stratum number (12). The same situation appeared when 
setting stratum 12 option to another pps source. Every time the pps 
source with the lower stratum number was chosen(even gps pps (having 
stratum 12 number) had '*' in ntpq when ocxo and rubidium had '+' 
(having stratum 8 number)for all the time). During that all of the 
sources had very nice and nearly the same delay, offset and jitter.

Has someone any idea why it behaved so strange with pps sources?

Thank you for your help.

Best Regards,
Grzegorz Daniluk

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