[ntp:questions] Request: step value modifcation&verfication in ntp.conf

Sowmya Manapragada skoganty at gmail.com
Sat Apr 8 14:30:22 UTC 2017


Hello,

A request, have a query on how to verify/test modifications done to ntp
step threshold value in ntp.conf:

ntp version: 4.2.8p9
OS: windows 7 in a small lan, clients configured to sync with timesync ntp
servers.
*Modifications done* :
*ntp.conf*
# Specifies the step threshold in seconds. The default without this command
is 0.128 s. If set to zero, step adjustments will never occur.# Note: The
kernel time discipline is disabled if the step threshold is set to zero or
greater than 0.5 s. Further details are on the
#  Clock State Machine page (
https://www.eecis.udel.edu/~mills/ntp/html/clock.html).
tinker step 0.128  => changed this to    ==>  tinker step 3
*query:*
 How do i really test verify this change is really working ?
documentation says this:
(https://www.eecis.udel.edu/~mills/ntp/html/clock.html)
If, due to extreme network congestion, an offset spike exceeds the step
threshold, by default 128 ms, the spike is discarded. However, if offset
spikes greater than the step threshold persist for an interval more than
the stepout threshold, by default 300 s, the system clock is stepped to the
correct time
 current observations:
1:> if offset > 3 sec (tinker step 3) ==> it appears clock is slewing --
not stepping
      if offset < 3 sec (tinker step 3) ===> it appears clock is slewing
(expected)
Not able to simulate condition where offset spike is > 3sec for an interval
more than stepout threshold (300 sec). Any method to simulate this condtion
?
other observations:
2:> if the ntp reference server time is 5:05 pm and my local clock is 5:00
pm => restart ntpd ==> clock "steps" and local clock time is stepped to
5:05 pm
3:>if the ntp reference server time is 5:05 pm and my local clock is 5:00
pm==>no restart of ntpd=> after 8 / 9 min, the local clock is synced with
the ntp reference time ( local clock is slewed and gradually adjusted to
sync to ntp reference time)


thanks in advance,
Shyam


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