[ntp:questions] Network problems affecting NTP
David Woolley
david at ex.djwhome.demon.invalid
Fri Jul 1 20:44:36 UTC 2011
Eugen COCA wrote:
> Due to a network problem on our provider, the packets were routed on a
Duplicate thread.
> different path than usual yesterday, for several hours. This period,
> NTP displayed wrong offsets:
>
> +GPS_NMEA(1) .GPS. 0 l 16 16 377 0.000
> 0.001 0.002
> ptbtime1.ptb.de .PTB. 1 u 4 64 377 64.545
> -4.450 0.140
> ntps1-1.cs.tu-b .PPS. 1 u 49 64 357 65.944
> -4.335 0.223
> ntp-p1.obspm.fr .TS-2. 1 u 27 64 377 68.793
> -4.233 0.034
> GPS-1.MIT.EDU .GPS. 1 u 53 64 377 155.543
> -4.491 1.779
> oPPS(1) .PPS. 0 l 9 16 377 0.000
> 0.001 0.002
> ntp1.usv.ro .PPS. 1 u 14 64 377 0.290
> 0.016 0.006
> ntp2.usv.ro .PPS. 1 u 4 64 377 0.229
> 0.017 0.027
> ntp3.usv.ro .PPS. 1 u 5 64 377 0.269
> 0.023 0.026
> -ptbtime2.ptb.de .PTB. 1 u 51 64 277 64.426
> -4.276 0.190
> -ntp0.rrze.uni-e .GPS. 1 u 29 64 377 55.088
> -4.486 0.039
> +ntp1.oma.be .PPS. 1 u 64 64 377 63.900
> -4.257 0.509
> -time-a.nist.gov .ACTS. 1 u 11 64 373 204.117
> 16.101 49.841
>
> After the problem was solved, the packets were routed on the usual
> path. The result is:
>
> +GPS_NMEA(1) .GPS. 0 l 35 64 377 0.000
> 0.001 0.002
> ptbtime1.ptb.de .PTB. 1 u 48 256 377 49.194
> -0.021 0.265
> ntps1-1.cs.tu-b .PPS. 1 u 69 256 377 50.778
> -0.044 0.675
> ntp-p1.obspm.fr .TS-2. 1 u 15 256 377 53.307
> 0.242 0.047
> GPS-1.MIT.EDU .GPS. 1 u 95 256 377 140.137
> -0.414 0.637
> oPPS(1) .PPS. 0 l 4 16 377 0.000
> 0.001 0.002
> ntp1.usv.ro .PPS. 1 u 31 64 377 0.198
> 0.000 0.003
> ntp3.usv.ro .PPS. 1 u 50 64 377 0.175
> -0.002 0.004
> ntp4.usv.ro .PPS. 1 u 56 64 377 0.198
> -0.020 0.005
> ptbtime2.ptb.de .PTB. 1 u 187 256 377 49.320
> 0.028 1.192
> ntp0.rrze.uni-e .GPS. 1 u - 256 377 39.578
> -0.073 0.028
> ntp1.oma.be .PPS. 1 u 184 256 377 48.966
> 0.068 0.124
> time-a.nist.gov .ACTS. 1 u 249 256 377 147.557
> 2.230 2.364
>
> One may observe the delays were also affected during this interval.
> Also, the time information served to clients was affected, the
> pool.ntp.org monitoring system confirmed the delay -
> http://www.pool.ntp.org/scores/80.96.120.252. It is obvious that a
> server synchronizing only with Internet sources will be in error as
> there is has no way to determine the problem. Can someone explain this
> behavior ?
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