[ntp:questions] NTP Peer Keeps Swapping on Start-up

SteveW qsw000 at email.mot.com
Mon Oct 4 15:19:49 UTC 2010


I am seeing a case where one board in my system keeps switching its
peer back and forth between its local clock and a remote ntp server
for about 40 minutes when it first comes up.  Eventually, it correctly
starts using the remote ntp server.

My setup includes a stratum 1 server (40.14.0.254) that is connected
to one board in my system (144.190.31.2).  The second board that is
swapping its peer back and forth is connected to this first board.
Both boards are running linux.  A snippet of some ntpq output is shown
below:

[09:36:02]      remote           refid      st t when poll reach
delay   offset  jitter
[09:36:02]
==============================================================================
[09:36:02] +144.190.31.2    40.14.0.254      2 u    5   16   17
0.365    0.022   0.004
[09:36:02] *LOCAL(1)        .LCL.           14 l    5   16   17
0.000    0.000   0.004

[09:37:02]      remote           refid      st t when poll reach
delay   offset  jitter
[09:37:02]
==============================================================================
[09:37:02] *144.190.31.2    40.14.0.254      2 u   11   16  177
0.365    0.022   0.004
[09:37:02]  LOCAL(1)        .LCL.           14 l    1   16  377
0.000    0.000   0.004

[09:37:12]      remote           refid      st t when poll reach
delay   offset  jitter
[09:37:12]
==============================================================================
[09:37:12] +144.190.31.2    40.14.0.254      2 u    3   16  377
0.345    0.012   0.011
[09:37:12] *LOCAL(1)        .LCL.           14 l   11   16  377
0.000    0.000   0.004

…


Any ideas why this would be happening, and what is the best approach
to debug?  Is there a specific ntpq command that can provide enough
information?  Is there a debug level that I can set when I start the
ntp daemon that will dump this information … if so, what should I be
looking for in the debug?

Many thanks,
SteveW




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