[ntp:questions] Strange server behaviour

Danny Mayer mayer at ntp.isc.org
Tue Jan 10 03:19:51 UTC 2006


Mauro Fiacco wrote:
> I have a stand-alone NTP server (ntp-v4.2.0), it is a freeBSD PC, with
> Rubidium PPS source. The server does not synchronize with higher stratum
> servers (although I monitor other servers with noselect).
> 
> Only one client uses it for synchronisation, over a private subnet.
> 
> When I start NTP the server measures its stability of about 5-10ppm 
> (as reported by ntpdc -c sysinfo), which converges to 2-5ppb within few
> hours.
> 
> Once the server has converged to ppb stability, I start my client, a
> run lasts for several days with the server maintaining good stability.
> 
> As I am testing with different client configurations, I need to stop and
> start the client every so often. When I do it, the stability of the
> server worsen instantaneously to ppm, before re-converge to lower
> values. As shown in the loopstats below:
> 
> ... very much stable to ppb range before this....
> 53744 42322.684 0.000000000 27.103912 0.000000954 0.001390 6
> 53744 42387.686 0.000000000 27.103912 0.000000954 0.001204 6
> 53744 42452.689 0.000000000 27.103912 0.000000954 0.001043 6
> ... here the client was killed ...
> 53744 42516.691 0.000000000 38.240784 0.000000954 5.568436 6
> 53744 42579.684 0.000000000 38.240784 0.000000954 4.822407 6
> 53744 42644.688 0.000000000 38.240784 0.000000954 4.176327 6
> 53744 42708.691 0.000000000 38.240784 0.000000954 3.616805 6
> 53744 42771.684 0.000000000 38.240784 0.000000954 3.132245 6
> 53744 42837.686 0.000000000 27.094574 0.000000954 6.198203 6
> 53744 42902.689 0.000000000 27.094574 0.000000954 5.367801 6
> 53744 42966.691 0.000000000 27.094574 0.000000954 4.648652 6
> 53744 43030.684 0.000000000 27.098007 0.000000954 4.025851 6
> 53744 43094.686 0.000000000 27.098007 0.000000954 3.486489 6
> 53744 43158.689 0.000000000 27.098007 0.000000954 3.019388 6
> 53744 43223.691 0.000000000 27.098007 0.000000954 2.614867 6
> 53744 43287.684 0.000000000 27.094116 0.000000954 2.264542 6
> ... slowly converging to ppb....
> 
> (Note that 0 offset and 0 network jitter are due to the fact that the
> server is not disciplined to any other server)
> 
> The problem is repeatable. I know it does make little sense... I am just
> at a loss with it. Any suggestions on why this is happening?
> 
> Thank you.
> 
> Mauro
> 
> PS:
> ntp.conf main parameters:
> 
> keys ./ntp.keys
> requestkey 1
> controlkey 1
> 
> driftfile /etc/ntp.drift
> 
> enable stats
> statistics loopstats peerstats clockstats rawstats sysstats
> filegen loopstats file loopstats type none enable
> filegen peerstats file peerstats type none enable
> filegen clockstats file clockstats type none enable
> filegen rawstats file rawstats type none enable
> filegen sysstats file sysstats type none enable
> 
> enable pps
> server 127.127.22.0
> fudge 127.127.22.0 stratum 1
> fudge 127.127.22.0 refid RBDM
> fudge 127.127.22.0 flag3 1
> 
> server zzzz.yyyy.net noselect
> 
> server 127.127.1.0
> fudge 127.127.1.0 stratum 1
> 
> restrict default kod notrap nomodify nopeer noquery
> restrict 127.0.0.1
> 
I don't understand why you would fudge the refclock to stratum 1 since
it should be stratum 0 and that's the default for a refclock. Even worse
you are also using a local clock and fudging it to stratum one. If you
have a refclock you certainly don't need a local clock. Get rid of that,
get ride of fudging the stratum of the refclock and things should become
normal.

Danny





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