[ntp:questions] Unexplained steps
Pierre Dubuc
pldubuc at yahoo.ca
Tue Sep 4 20:23:46 UTC 2007
Replying to message <ccadnTdE1bIKMkDbnZ2dnUVZ_q7inZ2d at megapath.net>
> Date: Tue, 04 Sep 2007 14:18:47 -0500
> From: Hal Murray <hal-usenet at ip-64-139-1-69.sjc.megapath.net>
> Newsgroups: comp.protocols.time.ntp
> Subject: Re: Unexplained steps
>
>
>> I'm totally confused by this series of snapshots below. Running 4.2.4p3
>> under NetBSD-3.1/patch, I started seeing some strange steps this morning.
>> I added some logging instructions in ntp.conf and restarted the daemon,
>> and the steps keep happening.
>
>> remote refid st t when poll reach delay offset jitter
>> ==========================================================================
>> +bonnie.Concordi 128.233.154. 2 u 100 128 377 6.343 2.477 2.026
>> -menthe.telecom. 204.123.2.5 2 u 102 128 377 7.382 1.237 0.961
>> -ecmail1.cmc.ec. 18.26.4.105 2 u 106 128 377 10.624 -4.249 0.521
>> *time.nrc.ca 132.246.168. 2 u 32 128 377 11.493 1.803 9.186
>> +time1.chu.nrc.c 209.87.233.5 2 u 93 128 377 17.017 2.217 2.699
>> -sylvester.sraq. 18.26.4.105 2 u 98 128 377 13.797 10.346 0.756
>
> THe above looks reasonable to me.
>
>
>>
>> remote refid st t when poll reach delay offset jitter
>> ==========================================================================
>> +bonnie.Concordi 132.205.122. 3 u 909 1024 377 7.226 -1.739 499.407
>> +menthe.telecom. 204.123.2.5 2 u 779 1024 377 10.374 -3.187 498.440
>> +ecmail1.cmc.ec. 18.26.4.105 2 u 904 1024 377 10.529 -7.725 499.646
>> +time.nrc.ca 132.246.168. 2 u 848 1024 377 14.625 0.161 27.797
>> *time1.chu.nrc.c 209.87.233.5 2 u 254 1024 377 1014.49 496.743 0.644
>> +sylvester.sraq. 18.26.4.105 2 u 4 1024 377 1016.93 508.733 2.030
>
> That looks strange/bad.
>
>
>> Sep 4 13:57:16 mac ntpd[7566]: time reset +0.496903 s
>> Sep 4 13:57:49 mac ntpd[7566]: synchronized to 199.212.17.21, stratum 2
>> Sep 4 13:57:50 mac ntpd[7566]: time reset -0.505313 s
>> Sep 4 13:58:08 mac ntpd[7566]: synchronized to 132.208.250.3, stratum 2
>
> It stepped 1/2 second in one direction, and then stepped back
> roughly the same amount.
>
> What's your connection to the network like? A link with a delay
> of about a second in one direction for a while might explain that
> sort of quirk. It could also be something strange "out there"
> somewhere in the great network between your ISP and the rest
> of the world.
>
I didn't notice anything different about the connection. I tried to ping
one of the servers a few minutes before the step, when the billboard looks
like everything is about to bust, and got something like a 28ms round
trip, which is perfectly normal.
I did turn off the router's logging feature. I don't know enough about its
inner workings, but it may be performing some kind of reverse DNS lookup
as part of its logging, and may very well hold up the connection until the
lookup is complete. We'll see how that goes...
--
Pierre Dubuc
pldubuc at yahoo.ca
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