| RE: [chrony-users] need help with large delays reported in ntpdata |
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Thanks Miroslav.
The server is a Masterclock GMR1000. Funny enough, as soon as I disconnected the 1pps input pulse to that GMR1000 unit, and it falls back to GPS for reference, then the precision is improved by a lot. For example:
Stratum 1 with 1pps input (as reported in the output of chronyc ntpdata command):
Remote address : ***.***.52.242 (***634F2)
Remote port : 123
Local address : ***.***.52.101 (***63465)
Leap status : Normal
Version : 3
Mode : Server
Stratum : 1
Poll interval : 10 (1024 seconds)
Precision : -5 (0.031250000 seconds)
Root delay : 0.000000 seconds
Root dispersion : 0.000000 seconds
Reference ID : 474D5200 (GMR)
Reference time : Tue Apr 06 18:13:51 2021
Offset : -0.000000193 seconds
Peer delay : 0.031250019 seconds
Peer dispersion : 0.031250019 seconds
Response time : 0.000412496 seconds
Jitter asymmetry: +0.00
NTP tests : 111 111 1101
Interleaved : No
Authenticated : No
TX timestamping : Kernel
RX timestamping : Kernel
Total TX : 8095
Total RX : 8095
Total valid RX : 8095
Same stratum 1 with 1pps disconnected, shortly after, using GPS as fallback:
Remote address : ***.***.52.242 (***634F2)
Remote port : 123
Local address : ***.***.52.101 (***63465)
Leap status : Normal
Version : 3
Mode : Server
Stratum : 1
Poll interval : 10 (1024 seconds)
Precision : -18 (0.000003815 seconds)
Root delay : 0.000000 seconds
Root dispersion : 0.000000 seconds
Reference ID : 474D5200 (GMR)
Reference time : Tue Apr 06 18:19:15 2021
Offset : -0.000027722 seconds
Peer delay : 0.000116265 seconds
Peer dispersion : 0.000003832 seconds
Response time : 0.000400542 seconds
Jitter asymmetry: +0.00
NTP tests : 111 111 1111
Interleaved : No
Authenticated : No
TX timestamping : Kernel
RX timestamping : Kernel
Total TX : 8105
Total RX : 8105
Total valid RX : 8105
I wonder what might be causing this discrepancy between the 2 references.
Thanks,
Andre
--
Andre Charbonneau
Frequency & Time
Metrology Research Centre
National Research Council Canada / Government of Canada
andre.charbonneau@xxxxxxxxxxxxxx / 613-993-3129
Fréquence et temps
Centre de recherche en métrologie
Conseil national de recherches Canada / Gouvernement du Canada
andre.charbonneau@xxxxxxxxxxxxxx / 613-993-3129
-----Original Message-----
From: Miroslav Lichvar [mailto:mlichvar@xxxxxxxxxx]
Sent: April 6, 2021 4:15 AM
To: chrony-users@xxxxxxxxxxxxxxxxxxxx
Subject: Re: [chrony-users] need help with large delays reported in ntpdata
***ATTENTION*** This email originated from outside of the NRC. ***ATTENTION*** Ce courriel provient de l'extérieur du CNRC
On Sat, Apr 03, 2021 at 07:33:13PM +0000, Charbonneau, André wrote:
> Precision : -5 (0.031250000 seconds)
> Root delay : 0.000000 seconds
> Root dispersion : 0.000000 seconds
> Reference ID : 474D5200 (GMR)
> Reference time : Sat Apr 03 18:55:15 2021
> Offset : +0.000004316 seconds
> Peer delay : 0.031250019 seconds
> Peer dispersion : 0.031250019 seconds
> These peer delay and peer dispersion values are quite large (being connected to the same switch) and constant over time (they don't change). I was looking at the chrony code and this looks like this could be due because of large estimated error?
chrony as a client rounds up the peer delay and dispersion to the precision reported by the server. -5 is not great. What kind of server is that?
--
Miroslav Lichvar
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