[ntp:questions] large dispersion

Dave dave.deconsulting at gmail.com
Wed May 23 15:27:50 UTC 2007


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!




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