[ntp:questions] Offset is always increasing

Riccardo Castellani ric.castellani at alice.it
Tue May 21 11:57:49 UTC 2013


I'm using n. 1 ntp server (XNTPD daemon on HP-UX, called FORCLIENTS,

192.168.1.240) for my clients and I'm obtaining the message
"synchronization 
lost" about every 20 minutes.
Source time is another server (MASTER) on my lan 
which updates its time
directly from Internet servers.


MASTER is OK

FORCLIENTS has a high offset !


ntp.conf of FORCLIENTS (192.168.1.240):


restrict default ignore
server 10.2.3.5
driftfile /etc/ntp.drift
restrict 
127.0.0.1
restrict 127.127.1.1
restrict 10.2.3.5
restrict 192.168.1.240

restrict 192.168.0.0 mask 255.255.0.0 nomodify noquery
server 127.127.1.1
fudge 
127.127.1.1 stratum 10 # show poor quality



ntp.conf of MASTER (10.2.3.5):


restrict default ignore
restrict 127.0.0.1
restrict 192.168.1.240 mask 
255.255.255.255 nomodify
restrict ntp1.inrim.it mask 255.255.255.255 nomodify 
noquery notrap nopeer
restrict ntp2.inrim.it mask 255.255.255.255 nomodify 
noquery notrap nopeer
restrict ntp1.fau.de mask 255.255.255.255 nomodify 
noquery notrap nopeer
restrict ntp2.nl.net mask 255.255.255.255 nomodify 
noquery notrap nopeer
restrict 127.127.1.0 mask 255.255.255.255
server ntp1.
inrim.it
server ntp2.inrim.it
server ntp1.fau.de
server ntp2.nl.net
server 
127.127.1.0
fudge 127.127.1.0
driftfile /var/lib/ntp/drift







My server log 
shows:


20 May 14:38:20 xntpd[19386]: synchronized to LOCAL(1), stratum=10
20 
May 14:39:23 xntpd[19386]: synchronized to 10.2.3.5, stratum=2
20 May 14:54:18 
xntpd[19386]: time reset (step) -1.014343 s
20 May 14:54:18 xntpd[19386]: 
synchronisation lost
20 May 14:58:35 xntpd[19386]: synchronized to LOCAL(1), 
stratum=10
20 May 14:59:38 xntpd[19386]: synchronized to 10.2.3.5, stratum=2
20 
May 15:14:33 xntpd[19386]: time reset (step) -1.010761 s
20 May 15:14:33 xntpd
[19386]: synchronisation lost
20 May 15:16:08 xntpd[13208]: logging to file 
/var/adm/syslog/ntp.log
20 May 15:16:08 xntpd[13208]: tickadj = 625, tick = 
10000, tvu_maxslew =
61875
20 May 15:16:08 xntpd[13208]: precision = 6 usec
20 
May 15:17:29 xntpd[14031]: logging to file /var/adm/syslog/ntp.log
20 May 15:17:
29 xntpd[14031]: tickadj = 625, tick = 10000, tvu_maxslew =
61875
20 May 15:17:
29 xntpd[14031]: precision = 10 usec
20 May 15:21:46 xntpd[14031]: synchronized 
to 10.2.3.5, stratum=2
20 May 15:21:46 xntpd[14031]: time reset (step) 
-0.216182 s
20 May 15:21:46 xntpd[14031]: synchronisation lost
20 May 15:26:03 
xntpd[14031]: synchronized to LOCAL(1), stratum=10
20 May 15:27:06 xntpd
[14031]: synchronized to 10.2.3.5, stratum=2
20 May 15:42:01 xntpd[14031]: time 
reset (step) -1.005840 s
20 May 15:42:01 xntpd[14031]: synchronisation lost
20 
May 15:46:18 xntpd[14031]: synchronized to LOCAL(1), stratum=10
20 May 15:47:21 
xntpd[14031]: synchronized to 10.2.3.5, stratum=2
20 May 16:02:16 xntpd[14031]: 
time reset (step) -1.009925 s
20 May 16:02:16 xntpd[14031]: synchronisation 
lost
20 May 16:06:33 xntpd[14031]: synchronized to LOCAL(1), stratum=10
20 May 
16:07:36 xntpd[14031]: synchronized to 10.2.3.5, stratum=2



nptd -qn shows:




remote refid st t when poll reach delay offset
disp

============================================================================
==

10.2.3.5 193.204.114.232 2 u 16 64 7 1.92 -158.96 3927.72
127.127.1.1 
127.127.1.1 10 l 15 64 17 0.00 0.000
1885.01



My time source server is ok 
(10.2.3.5) and I can exclude problems into my
lan.



remote local st poll 
reach delay offset disp

=======================================================================
=ntp1.
nl.uu.net 10.2.3.5 1 1024 377 0.04411 -0.003625 0.12183
=ntp1.inrim.it 10.2.3.5 
1 1024 377 0.01971 -0.000409 0.12172
*ntp2.inrim.it 10.2.3.5 1 1024 377 0.01923 
-0.000046 0.12175
=LOCAL(0) 127.0.0.1 10 64 377 0.00000 0.000000 0.03072
=ntp1.
rrze.uni-e 10.2.3.5 1 1024 377 0.05191 -0.009084 0.12178





Can you indicate 
suggestions please ? The problem is Offset bigger 128 ms
?!?! Offset is 
increasing until to 700-800 ms.

I run ntpdate to update immediately clock and 
I can see small offset but
after few minutes grows again until to exceed 128 
ms.

How can I solve it ?


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