| Re: [chrony-users] Two nearly identical boxes behaving differently |
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On 10/11/17 04:16, Miroslav Lichvar wrote:
On Fri, Nov 10, 2017 at 03:39:13AM +1100, Paul J R wrote:
The config on both is identical:
refclock SHM 0 offset 0.395 delay 0.2 refid NMEA noselect
refclock PPS /dev/pps0 refid PPS poll 4 prefer lock NMEA
server 10.69.69.1
One cant seem to poll pps:
root@ntp03:~# chronyc sources
210 Number of sources = 3
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#? NMEA 0 4 377 10 -264ms[ -264ms] +/-
110ms
#? PPS 0 4 0 - +0ns[ +0ns] +/- 0ns
^* 10.69.69.1 2 6 177 46 -4689ns[ -14us] +/-
92ms
The offset of the NMEA source is probably too large to be locked with
the PPS. You will need to adjust the offset value on the SHM line to
bring it closer to UTC and allow PPS to lock.
Indeed that did turn out to be the issue, thanks for the pointer, hadn't
considered that. Haven't really tried too many gps/pps implementations
with chrony so far so somewhat new territory for me. Having said that,
this is the first one i've built with and mtk3339 chip in it as well.
Thanks for the pointer!
And the other cant poll the server:
root@ntp04:~# chronyc sources
210 Number of sources = 3
MS Name/IP address Stratum Poll Reach LastRx Last sample
===============================================================================
#? NMEA 0 4 377 19 -24ms[ -24ms] +/-
105ms
#* PPS 0 4 277 18 +39ns[ -5ns] +/-
56ns
^? 10.69.69.1 0 7 377 - +0ns[ +0ns] +/-
0ns
As a first step, it would be good to confirm that the server is
responding. tcpdump-mini would be a good tool for that. :) If it does
respond, then a second step would be to recompile chrony with
debugging enabled, run chronyd with -d -d and see if there is
anything interesting.
I can only guess when i soldered in the gps board i've damaged the
router in some spectacularly unique way. Even down to the bit level, the
boxes are identical. I added a few more time sources and one has issues
with some time servers (but not all), the other works without issue. Did
a mirror port on the switch its connected to and data looks fine,
switched their configs around, changed the port they're plugged into,
tested their network latency and bandwidth, everything checks out. Last
step is to recompile the firmware with debug on.
Running them with only gps/pps time sources and pointing clients at
them, they perform almost the same too, so why one refuses to talk to
some time sources and the other is working ok is quite mystifying and
hopefully debug might tell me a few things.
Thanks for the reply!
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