[ntp:questions] Server stopped syncing to PPS?
Peter Eriksson
peter at ifm.liu.se
Fri Feb 3 10:09:55 UTC 2006
How can one find out *why* a server suddenly decieded that the
PPS signal should be ignored (even though it looks just fine)
after having been running fine for a day or so? (It choose the PPS
source after a little while just as it should behave).
System: Sun Ultra 5, Solaris 9, NTP 4.2.0a, ARBITER GPS clock
# /ifm/bin/ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
+ntp1.sp.se .PPS. 1 u 66 64 376 12.803 1.646 3.563
+ntp2.sp.se .PPS. 1 u 45 64 377 15.386 2.901 2.184
+Time1.Stupi.SE .PPS. 1 u 57 64 377 11.445 3.674 3.145
+Time2.Stupi.SE .PPS. 1 u 21 64 377 10.441 3.154 1.139
+ntp0-rz.rrze.un .GPS. 1 u 17 64 377 74.422 2.797 2.686
+ntps1-0.cs.tu-b .PPS. 1 u 70 64 176 75.067 3.061 11.140
+time.nist.gov .ACTS. 1 u 50 64 377 157.545 2.023 3.557
-time-b.nist.gov .ACTS. 1 u 15 64 377 124.831 -6.468 4.648
+timekeeper.isi. .GPS. 1 u 53 64 177 197.808 3.831 7.902
+cornelis.lysato 192.36.134.17 2 u 46 64 377 5.733 3.328 3.954
*GPS_ARBITER(0) .GPS. 0 l 59 64 376 0.000 0.020 0.022
-PPS(0) .PPS. 0 l 24 64 377 0.000 0.053 0.010
On a related issue - what's the correct procedure to adjust the offset for
the GPS and PPS signals so that my server will be more in "sync" with
other NTP servers around the world?
As you can see from the list I added a number of stratum 1 servers to my
config in order to try to see what the offset really should be, but it's
kind of hard to really decided that it should be. And 'time-b.nist.gov'
seems to be really off a lot of time...
Another issue that I've seen is that if I unplug the serial cable from
the GPS and then after a while reinsert the cable it seems like NTPD never
starts talking to the GPS again. Dunno why though... This is a bit annoying
(think power outage that temporarily kills the GPS receiver but not the
server).
Config file:
# more /etc/ntp.conf
enable pps
server ntp1.sp.se
server ntp2.sp.se
server time1.stupi.se
server time2.stupi.se
server ntp0.fau.de
server ntps1-0.cs.tu-berlin.de
server time.nist.gov
server time-b.nist.gov
server timekeeper.isi.edu
server cornelis.lysator.liu.se
### Arbiter GPS clock
server 127.127.11.0 prefer
fudge 127.127.11.0 time1 0.02015
### PPS Discipline
server 127.127.22.0
fudge 127.127.22.0 flag3 1
#fudge 127.127.22.0 time1 0.002
driftfile /etc/ntp.drift
statsdir /var/ntp/ntpstats/
statistics loopstats clockstats
filegen loopstats file loopstats type day link enable
filegen clockstats file clockstats type day link enable
- Peter
--
--
Peter Eriksson <peter at ifm.liu.se> Phone: +46 13 28 2786
Computer Systems Manager/BOFH Cell/GSM: +46 705 18 2786
Physics Department, Linköping University Room: Building F, F203
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