[ntp:questions] Problem troubleshooting gps/pps on freebsd 8.1

Peter S pst at telia.com
Thu Dec 16 15:01:29 UTC 2010

> You may be suffering from a refclock_nmea bug where multiple sentences
> were processed including stuffing an offset in the clock filter, when
> only one should go that far.  Either configure the GPS to send only
> one of GPRMC or GPGGA (both of which ntpd understands) or refer to
> html/driver/driver20.html for the mode to use in ntp.conf to instruct
> it to process only one or the other of the sentences you're seeing
> each second.

That's great Dave. I upgraded to 4.2.7p78 and it started to work!

[root@ ~]# ntpq -p
     remote           refid      st t when poll reach   delay
offset  jitter
oGPS_NMEA(0)     .GPS.            0 l   12   16  377    0.000
-0.001   0.002

Now that it is working I wonder how I should best configure ntp.
I will have two ntp servers on two separate LANs but with a firewall
in between.

Both ntp servers have their own GPS with PPS so I guess I want each
server to use that but if it's not working fall back to using the
other ntp server through the firewall. The ntp servers can't access
the internet. If both GPS stopped working or have lost their fix I
would like both ntp servers to still be in sync to each other.

Any suggestions would be much appreciated!


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