[ntp:questions] Ginormous offset and slow convergance

Pete Ashdown pashdown at xmission.com
Tue Nov 29 18:42:27 UTC 2011


Running with an Oncore GPS & a TAPR TAC.  If I "ntpdate -b" a nearby
synchronized server before I start ntpd, the offsets initially look pretty
good:

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 GPS_ONCORE(0)   .GPS.            0 l    -   16    0    0.000    0.000   0.000
 time-C.timefreq .ACTS.           1 u   39   64    1   37.534  -11.785   0.001
 ntp-nasa.arc.na .GPS.            1 u   38   64    1   19.868   -0.948   0.001

As time goes on, things start to get crazier:

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
xGPS_ONCORE(0)   .GPS.            0 l    6   16  377    0.000  -999.97   0.003
 time-C.timefreq .ACTS.           1 u   50   64    3   37.370  -16011.   0.080
 ntp-nasa.arc.na .GPS.            1 u   52   64    3   19.823  -16000.   0.046

More time with 100% reachability:

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
xGPS_ONCORE(0)   .GPS.            0 l    5   16  377    0.000  -15999.   0.002
+time-C.timefreq .ACTS.           1 u   19   64  377   37.887  -16011.   0.122
*ntp-nasa.arc.na .GPS.            1 u   24   64  377   19.760  -16000.   0.027

Finally after 30 minutes, a lock and convergence, but still big offsets:

     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
oGPS_ONCORE(0)   .GPS.            0 l    4   16  377    0.000  172.425  34.702
+time-C.timefreq .ACTS.           1 u   29   64   77   37.579  151.544 104.339
*ntp-nasa.arc.na .GPS.            1 u   22   64   77   19.779  165.811 106.581


Is there anything I can do to decrease the convergence time?



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