High Jitter in NTP and poll value never goes above 128
- by Aseem
I have a lot of servers syncing to the same NTP servers (4). Not every server is in the same LAN. Some are 3 hops away from the NTP servers and some are 6 hops away.
On couple of servers I see that the poll value never touches the 1024 mark and the jitter value is in double digits. Could it be due to the system hardware? These are windows servers (physical) and require as accurate time as possible. Please advice what I should do.
Some of the stats that I collected manually from the bad box (which is 6 hops away from the ntp servers)
C:\Program Files (x86)\NTP>ntpq -p -n
remote refid st t when poll reach delay offset jitter
==============================================================================
+*.*.*.25 *.*.*.233 2 u 12 128 377 1.210 -12.579 14.913
+*.*.*.26 *.*.*.233 2 u 96 128 377 1.067 -2.235 9.885
**.*.*.27 *.*.*.233 2 u 24 128 377 1.038 -7.569 11.178
+*.*.*.28 *.*.*.233 2 u 49 128 377 1.288 -11.058 14.544
remote refid st t when poll reach delay offset jitter
==============================================================================
+*.*.*.25 *.*.*.233 2 u 124 128 377 0.614 -6.212 5.329
+*.*.*.26 *.*.*.233 2 u 93 128 377 0.910 -9.431 3.111
+*.*.*.27 *.*.*.233 2 u 1 128 377 0.824 -7.428 3.129
**.*.*.28 *.*.*.233 2 u 84 128 377 1.503 -8.230 3.511
remote refid st t when poll reach delay offset jitter
==============================================================================
**.*.*.25 *.*.*.233 2 u 117 128 377 1.235 -4.084 11.405
+*.*.*.26 *.*.*.233 2 u 96 128 377 1.335 -11.813 13.130
+*.*.*.27 *.*.*.233 2 u 130 128 377 1.549 -14.036 16.381
-*.*.*.28 *.*.*.233 2 u 79 128 377 1.258 13.395 22.203
remote refid st t when poll reach delay offset jitter
==============================================================================
**.*.*.25 *.*.*.233 2 u 88 128 377 1.235 -4.084 14.068
+*.*.*.26 *.*.*.233 2 u 63 128 377 1.335 -11.813 17.086
+*.*.*.27 *.*.*.233 2 u 103 128 377 1.549 -14.036 20.691
-*.*.*.28 *.*.*.233 2 u 47 128 377 1.258 13.395 20.231
remote refid st t when poll reach delay offset jitter
==============================================================================
+*.*.*.25 *.*.*.233 2 u 47 64 377 0.652 -15.805 14.077
**.*.*.26 *.*.*.233 2 u 11 64 377 1.013 -14.423 11.375
-*.*.*.27 *.*.*.233 2 u 63 64 377 0.765 -2.030 7.680
+*.*.*.28 *.*.*.233 2 u 4 64 377 1.191 -17.980 14.393
remote refid st t when poll reach delay offset jitter
==============================================================================
-*.*.*.25 *.*.*.233 2 u 3 128 377 1.576 18.665 21.999
+*.*.*.26 *.*.*.233 2 u 73 128 377 0.637 -5.012 14.405
**.*.*.27 *.*.*.233 2 u 127 128 377 0.272 -8.237 14.438
+*.*.*.28 *.*.*.233 2 u 123 128 377 1.190 -14.383 18.875
C:\Program Files (x86)\NTP>ntpdc -c loopinfo
offset: -0.016430 s
frequency: 7.106 ppm
poll adjust: 18
watchdog timer: 133 s
offset: -0.016430 s
frequency: 7.106 ppm
poll adjust: 18
watchdog timer: 341 s
offset: -0.000149 s
frequency: 6.645 ppm
poll adjust: 0
watchdog timer: 383 s
offset: 0.015735 s
frequency: 6.725 ppm
poll adjust: 7
watchdog timer: 577 s
offset: -0.010331 s
frequency: 6.748 ppm
poll adjust: 21
watchdog timer: 567 s
offset: -0.009427 s
frequency: 6.687 ppm
poll adjust: 28
watchdog timer: 301 s
offset: -0.007361 s
frequency: 6.612 ppm
poll adjust: 30
watchdog timer: 155 s
offset: -0.008106 s
frequency: 4.358 ppm
poll adjust: 30
watchdog timer: 291 s
NTP.conf
# NTP configuration file
# Use drift file
driftfile "C:\Program Files (x86)\NTP\ntp.drift"
# Logs
statistics loopstats peerstats clockstats
statsdir "C:\Program Files (x86)\NTP\logs\" # directory for statistics files
filegen peerstats file peerstats type day enable
filegen loopstats file loopstats type day enable
filegen clockstats file clockstats type day enable
logfile "C:\Program Files (x86)\NTP\logs\syslog.txt"
# Use specific NTP servers
server *.*.*.25 minpoll 4 maxpoll 7 iburst
server *.*.*.26 minpoll 4 maxpoll 7 iburst
server *.*.*.27 minpoll 4 maxpoll 7 iburst
server *.*.*.28 minpoll 4 maxpoll 7 iburst
