[ntp:questions] debugging strange ntp in virtual environment

Riccardo Castellani ric.castellani at alice.it
Wed Sep 18 17:16:42 UTC 2013


My NTP server has strange problem and my clients cannot update their time 
clock.
My NTP server is Linux and NTP version is 4.2.0.a
This NTP server is a virtual machine (by P2V) but few months ago it was 
working fine.
My clients get following msg when I run ntpd daemon: 'no server suitable for 
synchronization found'
In client 'A' I run this command 'ntpq -pn' :

     remote           refid      st t when poll reach   delay   offset 
disp
==============================================================================
 myntpserver    0.0.0.0         16 u   29   64    0     0.00    0.000 
16000.0


In client 'B' I run this command 'ntpq -pn' :
     remote           refid      st t when poll reach   delay   offset 
disp
==============================================================================
myntpserver    83.84.69.80     16 u   38   64    0     2.78  -758.11 16000.0

In NTP server 'ntpq -pn' shows:

     remote           refid      st t when poll reach   delay   offset 
jitter
==============================================================================
*193.204.114.232 .CTD.            1 u   22   64  375   20.863  -672.31 
232.744
+193.204.114.233 .CTD.            1 u   22   64  377   20.846  -884.47 
178.639
+193.79.237.14   .PPS.            1 u   17   64  377   26.264  -819.79 
181.462
x192.93.2.20     .GPSi.           1 u   16   64  377   32.996  -1039.3 
262.130
+131.188.3.221   .DCFp.           1 u   22   64  377   42.731  -818.20 
179.726

I reset drift file, I restarted daemon but 'offset' value increases in few 
hours until to be 800-1000.

In NTP server 'ntpq -c rv' shows:

assID=0 status=c6f4 sync_alarm, sync_ntp, 15 events, event_peer/strat_chg,
version="ntpd 4.2.0a at 1.1196-r Fri May 12 09:51:35 EDT 2006 (1)"?,
processor="i686", system="Linux/2.6.11-1.1369_FC4smp", leap=11,
stratum=16, precision=-18, rootdelay=0.000, rootdispersion=197.910,
peer=18845, refid=STEP,
reftime=00000000.00000000  Thu, Feb  7 2036  7:28:16.000, poll=6,
clock=0xd5e45b57.a691d9b1, state=2, offset=0.000, frequency=0.000,
noise=775.898, jitter=238.455, stability=0.000


I installed another server (this time physical server) in the same lan, 
configured in the same way, same ntp version and it works fine!!!
It's physical server, unique difference ! Clients can update time from 
physical server and no update from the virtual server !

In physical server  'ntpq -pn' shows:

     remote           refid      st t when poll reach   delay   offset 
jitter
==============================================================================
*193.204.114.232 .CTD.            1 u  216  512  335   22.177   -4.268 
0.244
+193.204.114.233 .CTD.            1 u   98  512  331   20.756   -4.873 
0.351
-131.188.3.221   .DCFp.           1 u  201  512  335   49.258  -12.984 
2.276
+193.79.237.14   .PPS.            1 u  203  512  335   27.570   -5.418 
1.051

In physical server 'ntpq -c rv' shows:

assID=0 status=0644 leap_none, sync_ntp, 4 events, event_peer/strat_chg,
version="ntpd 4.2.0a at 1.1196-r Fri May 12 09:51:35 EDT 2006 (1)"?,
processor="i686", system="Linux/2.6.11-1.1369_FC4smp", leap=00,
stratum=2, precision=-17, rootdelay=22.177, rootdispersion=35.682,
peer=64524, refid=193.204.114.232,
reftime=d5e45b36.ce35610a  Wed, Sep 18 2013 19:02:46.805, poll=9,
clock=0xd5e45c4d.f6807bbb, state=4, offset=-4.293, frequency=8.223,
noise=0.823, jitter=0.951, stability=40.108


Can you help me to debug my problem 



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