[ntp:questions] jumpy offset/drift

Folkert van Heusden folkert at vanheusden.com
Thu Aug 11 09:15:47 UTC 2005


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

I did some investigating and found that ntpd constantly switches between
servers and my local DCF receiver:

D: Thu Aug 11 09:45:39 CEST 2005
remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*GENERIC(0)      .DCFa.           0 l   44   64  377    0.000   -1.263   1.551
xkeetweej.intran 193.79.237.14    2 u   57   64  376    0.292  -36.520   0.295
+auth1.xs4all.nl 131.188.3.220    2 u   40   64  377    8.192  -16.940   0.719
+ntp1.nl.net     .GPS.            1 u   28   64  377   18.124  -17.941   1.943
+ntp3-rz.rrze.un .DCFp.           1 u   51   64  377   27.485  -17.906   0.988
+sombrero.cs.tu- .PPS.            1 u    7   64  377   26.379  -18.645   3.443

D: Thu Aug 11 09:50:39 CEST 2005
remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*GENERIC(0)      .DCFa.           0 l   24   64  377    0.000    1.781   2.965
- -keetweej.intran 193.79.237.14    2 u   37   64  376    0.329  -36.585   0.476
+auth1.xs4all.nl 131.188.3.220    2 u   15   64  377    8.152  -16.526   8.678
+ntp1.nl.net     .GPS.            1 u    7   64  377   17.500  -17.683   1.116
+ntp3-rz.rrze.un .DCFp.           1 u   33   64  377   27.760  -17.762   1.060
+sombrero.cs.tu- .PPS.            1 u   48   64  377   26.379  -18.645   0.607

D: Thu Aug 11 09:55:39 CEST 2005
remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
xGENERIC(0)      .DCFa.           0 l    3   64  377    0.000    0.727   1.553
- -keetweej.intran 131.188.3.223    2 u   12   64  377    0.001  -32.863   2.539
+auth1.xs4all.nl 131.188.3.220    2 u   54   64  377    7.980  -16.840   0.632
*ntp1.nl.net     .GPS.            1 u   51   64  377   17.500  -17.683   1.480
+ntp3-rz.rrze.un .DCFp.           1 u    8   64  377   27.336  -17.719   0.239
+sombrero.cs.tu- .PPS.            1 u   25   64  377   26.345  -18.291   1.270

D: Thu Aug 11 10:00:39 CEST 2005
remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
xGENERIC(0)      .DCFa.           0 l   44   64  377    0.000   13.671  11.407
+keetweej.intran 130.149.17.8     2 u   51   64  376    0.001  -17.064  13.865
+auth1.xs4all.nl 131.188.3.220    2 u   30   64  377    7.980  -16.840   7.266
*ntp1.nl.net     .GPS.            1 u   29   64  377   18.400  -16.000   8.049
+ntp3-rz.rrze.un .DCFp.           1 u   48   64  377   27.336  -17.719   6.592
- -sombrero.cs.tu- .PPS.            1 u    2   64  377   26.126   -7.061   7.996

D: Thu Aug 11 10:05:39 CEST 2005
remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
xGENERIC(0)      .DCFa.           0 l   27   64  377    0.000   22.224   9.881
+keetweej.intran 130.149.17.8     2 u   31   64  376    0.001   -3.805  12.324
- -auth1.xs4all.nl 193.79.237.14    2 u    7   64  377    8.259   -8.542   7.900
*ntp1.nl.net     .GPS.            1 u    8   64  377   19.238   -2.778   4.548
+ntp3-rz.rrze.un .DCFp.           1 u   24   64  377   27.521    0.092   6.231
+sombrero.cs.tu- .PPS.            1 u   47   64  377   26.126   -7.061   4.784

D: Thu Aug 11 10:10:39 CEST 2005
remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
*GENERIC(0)      .DCFa.           0 l   65   64  377    0.000   12.240   6.299
+keetweej.intran 130.149.17.8     2 u    8   64  377    0.001   -3.805   5.810
+auth1.xs4all.nl 193.79.237.14    2 u   49   64  377    8.265   -2.311   4.822
+ntp1.nl.net     .GPS.            1 u   52   64  377   18.107   -6.202   7.203
+ntp3-rz.rrze.un .DCFp.           1 u    3   64  377   27.521    0.092   6.223
+sombrero.cs.tu- .PPS.            1 u   24   64  377   25.854    4.852   8.769

What I now don't understand is why it sometimes marks the dcf receiver
as a bad clock. The delay is constantly 0 and the offset as well as the
jitter are always low.


On Wed, Aug 10, 2005 at 12:48:20PM +0200, Folkert van Heusden wrote:
> Hi,
> 
> Can someone explain to me why the drift and offset are so jumpy on my
> system? http://keetweej.vanheusden.com/ntp_graph.png
> 
> remote           refid           st t when poll reach   delay  offset   jitter
> ==============================================================================
> *GENERIC(0)      .DCFa.           0 l    2   64  377    0.000 -2.335    1.702
> +keetweej.intran 131.188.3.223    2 u   65   64  376    0.454 -21.215   1.815
> +auth1.xs4all.nl 131.188.3.220    2 u   33   64  377    8.263 -20.380   1.771
> +ntp1.nl.net     .GPS.            1 u   47   64  377   18.165 -20.157   2.443
> +ntp3-rz.rrze.un .DCFp.           1 u   16   64  377   27.401 -20.976   1.243
> +sombrero.cs.tu- .PPS.            1 u   60   64  277   26.595 -20.917   8.623


Folkert van Heusden

- -- 
Auto te koop, zie: http://www.vanheusden.com/daihatsu.php
- --------------------------------------------------------------------
Get your PGP/GPG key signed at www.biglumber.com!
- --------------------------------------------------------------------
Phone: +31-6-41278122, PGP-key: 1F28D8AE
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.1 (GNU/Linux)

iIMEARECAEMFAkL7F0M8Gmh0dHA6Ly93d3cudmFuaGV1c2Rlbi5jb20vZGF0YS1z
aWduaW5nLXdpdGgtcGdwLXBvbGljeS5odG1sAAoJEDAZDowfKNiuHtsAn1mi1Vc1
ut7voMS0IjQ0IaBk87VcAJ9poZHoweVoUPcl3UfO2oo8bfQuHA==
=5HQt
-----END PGP SIGNATURE-----



More information about the questions mailing list