[ntp:questions] PPS Driver -- getting wrong REFID and stratum when peer isn't local refclock
John Ackermann N8UR
jra at febo.com
Sun Apr 16 16:29:15 UTC 2006
Hi --
I'm not sure if this is a bug, or a configuration problem. I'm running
ntp-stable-4.2.0a-20050720 on a FreeBSD 5.4 system with PPS kernel enabled.
I am trying to use the PPS driver with a refclock that provides only a
PPS signal on the DCD line, but no other timecode. Therefore, I am
using an external system as the prefer peer, and this, I think is the
problem.
Although the logs and billboard show that I am sync'd to the PPS signal
and all appears well (ntptime also shows expected kernel pps results),
there are two anomalies:
1. The "refid" is showing as the IP address of the (remote) prefer peer.
2. The stratum of the PPS clock shows as 1, not 0. As a result, the
machine advertises itself to remote hosts as a stratum 2 box.
Attached below are the output of ntpq -p, plus my ntp.conf file.
This behaviour breaks the ability to properly use a standalone PPS
source like a Cesium clock. Should it work this way? Is there
something wrong with my configuration? As a workaround, I'm wondering
whether the dreaded local refclock might be usable as the prefer peer,
since I'm using kernel time discipline to keep it sane. Does that make
sense?
Thanks,
John
----
Here's the output of ntpq -p:
tick# ntpq -p
remote refid st t when poll reach delay offset jitter
==============================================================================
oPPS(0) 192.168.1.230 1 l 24 64 377 0.000 0.001 0.004
+tock.febo.com .PPSG. 1 u 20 256 377 0.465 -0.021 0.041
-toe.febo.com .PPSW. 1 u 19 256 377 0.484 -0.034 0.083
+databox.febo.co .PPSG. 1 u 18 256 377 0.335 -0.047 0.005
(192.168.1.230 is tock.febo.com)
Here's ntp.conf:
# tick ntp.conf
logfile /var/log/ntpd
driftfile /etc/ntp.drift
statsdir /var/log/ntpstats/
statistics loopstats peerstats clockstats
filegen loopstats file loopstats type day enable
filegen peerstats file peerstats type day enable
filegen clockstats file clockstats type day enable
# PPS
enable pps
server 127.127.22.0
fudge 127.127.22.0 flag3 1
fudge 127.127.22.0 refid PPS
server tock.febo.com prefer iburst
server toe.febo.com iburst
server databox.febo.com iburst
More information about the questions
mailing list