[ntp:questions] NTP does not sync; increasing offset - problem with local clock?

Dr. Torsten Rupp rupp at aicas.com
Fri Jun 10 07:20:02 UTC 2005


Dear NTP-users,

I tried for a while to make NTP running on a Suse 9.0 based system, but 
it seems there is strange problem I do not understand: after starting 
ntpd it took some time to synchronize to a server. The log from ntpc:

*ntp1.ptb.de     192.168.1.20     1   16  377 0.02094 -0.032411 0.00124
=time-a.nist.gov 192.168.1.20     1   16  377 0.10571 -0.033428 0.00128

This looks nice, but after some time (a few minutes) the reported 
time-offset is increasing:

*ntp1.ptb.de     192.168.1.20     1   16  377 0.02083 14.481775 0.00075
=time-a.nist.gov 192.168.1.20     1   64  377 0.09814 12.172259 0.00266

The time on the computer is really quite wrong. It took some more time, 
then the time is adjusted in a single big step with the following output 
of ntpdc

=ntp1.ptb.de     192.168.1.20    16   16    0 0.00000  0.000000 0.00000
=time-a.nist.gov 192.168.1.20    16   16    0 0.00000  0.000000 0.00000
      remote           local      st poll reach  delay   offset    disp
=======================================================================
=ntp1.ptb.de     192.168.1.20    16   16    0 0.00000  0.000000 0.00000
=time-a.nist.gov 192.168.1.20    16   16    0 0.00000  0.000000 0.00000
      remote           local      st poll reach  delay   offset    disp
=======================================================================
=ntp1.ptb.de     192.168.1.20    16   16    0 0.00000  0.000000 0.00000
=time-a.nist.gov 192.168.1.20    16   16    0 0.00000  0.000000 0.00000
      remote           local      st poll reach  delay   offset    disp
=======================================================================
=ntp1.ptb.de     192.168.1.20     1   16    1 0.01979  0.016320 7.93750
=time-a.nist.gov 192.168.1.20     1   16    1 0.10609  0.012647 7.93750
      remote           local      st poll reach  delay   offset    disp
=======================================================================
=ntp1.ptb.de     192.168.1.20     1   16    1 0.01979  0.016320 7.93750
=time-a.nist.gov 192.168.1.20     1   16    1 0.10609  0.012647 7.93750
      remote           local      st poll reach  delay   offset    disp
=======================================================================
=ntp1.ptb.de     192.168.1.20     1   16    1 0.01979  0.016320 7.93750
=time-a.nist.gov 192.168.1.20     1   16    1 0.10609  0.012647 7.93750
      remote           local      st poll reach  delay   offset    disp

The problem does not disappear, even I wait for a whole day.

My questions:

- Why is NTP not able to keep the time in sync? Is there a problem with 
my local clock which seems to be too "slow" (more then 500 PPM)? Could 
there be a problem with the kernel (it is the orignal Suse 9.0 kernel 
2.4.21-215-athlon, no SMP)? Could there be missing interrupts? How do 
verify this?

- Why there is a server marked with a "*" even the time offset is quite 
large?

Any help is welcome. Thank you very much.

Torsten




More information about the questions mailing list