On 2015-02-03 03:32, François Meyer wrote:
Hi,
I have 2 stratum 1 Freebsd boxes in roughly the same configuration,
ie a network stratum 1 peer and a Cs 1PPS ; they are working
ok afaics, but both report a sys_jitter of 0.001907 that seem to be an
impasable lower limit. Does anyone have some link/explanation
regarding the mechanism behind this limit ?
What are your Cs drift rates?
What do your peerstats and loopstats show for these servers?
Below are ntpq -p and ntpq -c rv output for both machines :
saturne :
remote refid st t when poll reach delay offset jitter
==============================================================================
oPPS(0) .PPS. 0 l 25 64 377 0.000 0.001 0.002
+192.168.12.7 .PPS. 1 s 31 64 377 0.366 0.042 0.040
*ntp-p1.obspm.fr .TS-4. 1 s 123 64 372 11.399 0.012 0.378
associd=0 status=0115 leap_none, sync_pps, 1 event, clock_sync,
version="ntpd 4.2.8@1.3265-o Wed Jan 7 15:31:43 UTC 2015 (1)",
processor="i386", system="FreeBSD/10.1-RC3", leap=00, stratum=1,
precision=-19, rootdelay=0.000, rootdisp=1.375, refid=PPS,
reftime=d87b1e49.6f35f1e4 Tue, Feb 3 2015 10:15:37.434,
clock=d87b1e63.2e1257cd Tue, Feb 3 2015 10:16:03.179, peer=5700, tc=6,
mintc=3, offset=0.000750, frequency=-196.055, sys_jitter=0.001907,
clk_jitter=0.002, clk_wander=0.000, tai=35, leapsec=201507010000,
expire=201512280000, host="saturne.obs-besancon.fr", flags=0x80003,
digest="md5", signature="md5WithRSAEncryption", update=201501291235,
cert="saturne.obs-besancon.fr saturne.obs-besancon.fr 0x1",
until=201601151330
Note frequency drift is -196ppm - is this reasonable for this machine, and
is this number constantly increasing or just varying around this value?
192.168.12.7:
remote refid st t when poll reach delay offset jitter
==============================================================================
oPPS(0) .PPS. 0 l 5 64 377 0.000 -0.001 0.002
*saturne.obs-bes .PPS. 1 s 44 64 177 0.362 -0.033 0.029
ntp-p1.obspm.fr .INIT. 16 s - 1024 0 0.000 0.000 0.000
associd=0 status=01f8 leap_none, sync_pps, 15 events, no_sys_peer,
version="ntpd 4.2.8@1.3265-o Wed Jan 14 20:49:48 UTC 2015 (1)",
processor="i386", system="FreeBSD/10.1-RELEASE", leap=00, stratum=1,
precision=-19, rootdelay=0.000, rootdisp=1.090, refid=PPS,
reftime=d87b1c7d.57c3637c Tue, Feb 3 2015 10:07:57.342,
clock=d87b1c83.53a0827a Tue, Feb 3 2015 10:08:03.326, peer=28975, tc=6,
mintc=3, offset=-0.000736, frequency=-2.064, sys_jitter=0.001907,
clk_jitter=0.002, clk_wander=0.000, tai=35, leapsec=201507010000,
expire=201512280000
Note 192.168.12.7 shows no_sys_peer and ntp-p1.obspm.fr stuck in INIT.
Rootdisp on both systems seems pretty high for PPS sources.
Normally there is a GPS associated with each PPS source.
What are your PPS and time sources?
Do you have local preferred sources in both configs to provide UTC?
Are both servers defined to each other as peers?
Peers can not share any sources.
Common sources cause a timing loop error which should be logged.
What do your logs show?
Could you share your configs?
--
Take care. Thanks, Brian Inglis
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