[ntp:questions] NTP Stratum 1 performance

Miguel Gonçalves miguel.barbosa.goncalves at gmail.com
Sun May 12 14:18:15 UTC 2013


Hi!

Just added another GPS receiver (Trimble Acutime Gold) to the group of my
local NTP servers

ntp2# ntpq -pn
     remote           refid      st t when poll reach   delay   offset
 jitter
==============================================================================
*127.127.29.0    .GPS.            0 l   13   16  377    0.000   -0.005
0.028
o127.127.22.0    .PPS.            0 l   13   16  377    0.000    0.011
0.004
 10.0.2.3        .GPS.            1 u   13   16  377    0.144    0.003
0.008
 10.0.2.4        .PPS.            1 u   14   16  377    0.141    0.002
0.023

--- /var/log/ntp/loop ---
56424 50668.991 0.000005465 143.990 0.000001791 0.003282 4
56424 50684.990 0.000005338 143.990 0.000001049 0.003070 4
56424 50700.991 0.000004809 143.990 0.000001724 0.002872 4
56424 50716.991 0.000005051 143.990 0.000001031 0.002686 4
56424 50732.991 0.000004922 143.990 0.000001820 0.002513 4
56424 50748.991 0.000004719 143.990 0.000000884 0.002350 4
56424 50764.990 0.000005080 143.990 0.000003020 0.002199 4
56424 50780.991 0.000004878 143.990 0.000001369 0.002057 4
56424 50796.991 0.000003500 143.990 0.000001648 0.001924 4
56424 50812.991 0.000005153 143.979 0.000001416 0.004399 4
56424 50828.990 0.000002782 143.979 0.000001728 0.004115 4
56424 50844.990 0.000005969 143.979 0.000001363 0.003849 4
56424 50860.991 0.000006246 143.979 0.000001833 0.003600 4
56424 50876.991 0.000006221 143.979 0.000001225 0.003368 4
56424 50892.990 0.000007199 143.979 0.000001887 0.003150 4
56424 50908.990 0.000007880 143.979 0.000001045 0.002947 4
56424 50924.991 0.000008274 143.979 0.000001917 0.002756 4
56424 50940.991 0.000008683 143.979 0.000001362 0.002578 4
56424 50956.991 0.000007505 143.979 0.000001635 0.002412 4
56424 50972.990 0.000009421 143.979 0.000001218 0.002256 4
56424 50988.990 0.000010146 143.979 0.000002219 0.002110 4
56424 51004.991 0.000010624 143.979 0.000001026 0.001974 4
--- /var/log/ntp/loop ---

Just wondering what is the expected offset for a stratum 1 server as
10.0.2.3 and 10.0.2.4 are always under 5 us but this server (with Trimble
Acutime Gold) wanders a bit. The server has been turned on for 2 days now
so I guess it is stable. Additionally the room has AC and the temperature
is always around 22 ºC (I have a monitoring system the records the
temperature every minute and it wanders between 21 and 23).

Any ideas?

Regards,
Miguel


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