[ntp:questions] large dispersion

Dave dave.deconsulting at gmail.com
Fri May 25 13:28:09 UTC 2007


On May 24, 8:09 pm, "Richard B. Gilbert" <rgilber... at comcast.net>
wrote:
> Dave wrote:
> > On May 23, 1:16 pm, "Richard B. Gilbert" <rgilber... at comcast.net>
> > wrote:
>
> >>Dave wrote:
>
> >>>I'm experiencing large values of dispersion when I use 'ntpq -p':
>
> >>>3:22pm:ntp>ntpq -p
> >>>     remote           refid      st t when poll reach   delay
> >>>offset    disp
> >>>==============================================================================
> >>>*10.2.100.10     .GPS.            1 u   25   64  377     0.46
> >>>943.557  439.36
> >>>3:22pm:ntp>
>
> >>> but when I look at the peerstats log file, my dispersion is low:
>
> >>>3:22pm:ntp>tail /var/ntp/ntpstats/peerstats.log
> >>>54243 54804.018 10.2.100.10 9634 0.617563 0.00046 0.31154
> >>>54243 54868.013 10.2.100.10 9634 0.813226 0.00043 0.32210
> >>>54243 54932.018 10.2.100.10 9634 0.099169 0.00046 0.55225
> >>>54243 54996.010 10.2.100.10 9634 0.300057 0.00047 0.28690
> >>>54243 55060.014 10.2.100.10 9634 0.584358 0.00044 0.31111
> >>>54243 55124.009 10.2.100.10 9634 0.781632 0.00047 0.32353
> >>>54243 55188.014 10.2.100.10 9634 0.065932 0.00043 0.55287
> >>>54243 55252.013 10.2.100.10 9634 0.657674 0.00044 0.37859
> >>>54243 55316.018 10.2.100.10 9634 0.943557 0.00046 0.43936
> >>>54243 55380.013 10.2.100.10 9634 0.139388 0.00044 0.59772
> >>>3:23pm:ntp>
>
> >>> I'm also concerned with the large amount of maximum/estimated error
> >>>when I use the xntpdc command 'kerninfo':
>
> >>>xntpdc> kerninfo
> >>>pll offset:           0 us
> >>>pll frequency:        -391.137 ppm
> >>>maximum error:        524704 us
> >>>estimated error:      408368 us
> >>>status:               0089
> >>>pll time constant:    2
> >>>precision:            1 us
> >>>frequency tolerance:  512 ppm
> >>>pps frequency:        0.000 ppm
> >>>pps stability:        512.000 ppm
> >>>pps jitter:           200 us
> >>>calibration interval: 4 s
> >>>calibration cycles:   0
> >>>jitter exceeded:      0
> >>>stability exceeded:   0
> >>>calibration errors:   0
> >>>xntpdc>
>
> >>>Here is the output of the pstats command:
>
> >>>xntpdc> pstats 10.2.100.10
> >>>remote host:          10.2.100.10
> >>>local interface:      10.2.100.5
> >>>time last received:   3s
> >>>time until next send: 61s
> >>>reachability change:  2947s
> >>>packets sent:         59
> >>>packets received:     59
> >>>bad authentication:   0
> >>>bogus origin:         0
> >>>duplicate:            0
> >>>bad dispersion:       15
> >>>bad reference time:   0
> >>>candidate order:      1
> >>>xntpdc>
>
> >>>And lastly, my ntp.conf file:
>
> >>>3:25pm:inet>more ntp.conf
> >>>server 10.2.100.10             # NTP server
>
> >>>driftfile /etc/ntp.drift          # Drift available for next restart
> >>>logfile /var/ntp/ntp.log       # NTP logging
>
> >>>statsdir /var/ntp/ntpstats/
> >>>statistics loopstats peerstats clockstats
> >>>filegen loopstats file loopstats.log type day link enable
> >>>filegen peerstats file peerstats.log type day link enable
> >>>filegen clockstats file clockstats.log type day link enable
> >>>3:25pm:inet>
>
> >>>Anyone have any ideas? I have a GPS signal coming in to a Brandywine
> >>>NTA-100, which is configured at 10.2.100.10. Thanks in advance!
>
> >>If you are using "X"ntpdc you would appear to be using a version that
> >>may be as much as ten years old!   Just what are you using and what are
> >>  you running it on?
>
> > Wow you're right. Heres the version printout:
> > xntpdc 3-5.93e Mon Sep 20 15:47:24 PDT 1999 (1)
>
> > I'm running this on a Sun Fire 4200, Solaris 10. Something this old
> > comes installed on Solaris 10?
>
> Yup!
>
> I think it has something to do with the fact that there is, as yet, no
> RFC for NTP V4.  There is a committee, God help us, working on one.  I
> think it has been about a year now with no visible results!
>
> I'd suggest grabbing a more recent version of the code from somewhere.
> Sun Freeware and Blastwave sites should both have Solaris versions more
> recent than what Sun ships.  There have been quite a few fixes and
> enhancements since 3-5.93e.
>
> If you want/are able to build your own, try the ntp.org web site; there
> are links there to download the source to the stable and development
> versions which are, I believe, at 4.2.something.

I just downloaded ntp v4.2.4 from sunfreeware.com and I'll give that a
try. I'll let you know how it goes!




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