[ntp:questions] Local clock - sync issue

Kevin Oberman oberman at es.net
Mon Nov 8 19:54:59 UTC 2010


> From: Stephen Vaughan <Stephen.Vaughan at blackboard.com>
> Date: Mon, 8 Nov 2010 10:15:30 -0700
> 
> Hi All,
> 
> Is anyone able to shed some further light on this issue? I plan to remove the LOCAL clock from ntp's configuration, but I'm still keen to know why it's defaulting to the LOCAL clock once network connectivity is down, and then ignoring any of the public NTP servers configured when network connectivity returns. It stays locked to the LOCAL clock for weeks until we actually restart it manually.
> 
> Cheers,
> Stephen
> 
> -----Original Message-----
> From: Kevin Oberman [mailto:oberman at es.net]
> Sent: Wednesday, November 03, 2010 3:00 PM
> To: Stephen Vaughan
> Cc: questions at lists.ntp.org
> Subject: Re: [ntp:questions] Local clock - sync issue
> 
> > From: Stephen Vaughan <Stephen.Vaughan at blackboard.com>
> > Date: Tue, 2 Nov 2010 23:13:47 -0700
> > Sender: questions-bounces+oberman=es.net at lists.ntp.org
> >
> > Hi,
> >
> > We're having an issue with an NTPD whereby it's defaulting (or
> > whatever the correct terminology is) to the LOCAL clock, this is
> > occurring when one of our servers loses connectivity. We have 4
> > server's setup and the local clock is also configured:
> >
> > server  127.127.1.0     # local clock
> > fudge   127.127.1.0 stratum 10
> >
> > ntpq -p output:
> >
> >      remote           refid      st t when poll reach   delay   offset  jitter
> > ==============================================================================
> >  hostname .INIT.          16 u    - 1024    0    0.000    0.000   0.000
> >  hostname .INIT.          16 u    - 1024    0    0.000    0.000   0.000
> >  hostname .INIT.          16 u    - 1024    0    0.000    0.000   0.000
> >  hostname.INIT.          16 u    - 1024    0    0.000    0.000   0.000
> > *LOCAL(0)        .LOCL.          10 l    9   64  377    0.000    0.000   0.001
> >
> > The issue with this is that once it defaults to the LOCAL, it doesn't
> > sync with an external source again, until we manually restart
> > ntpd. I'm sure this is something simple, but I'm hoping someone can
> > assist.
> 
> Patient: Doctor, it hurts when I do this!
> Doctor: Then don't do that. Next patient!
> 
> Why do you have LOCAL in your ntp.conf? It is almost always a REALLY bad
> idea because it leaves the clock free-running.
> 
> It is oft discussed on this list why so many software distributions
> include LOCAL in the default ntp.conf. They really, really should stop
> doing it and so should you.
> 
> The real question is why you are not getting to any of the named servers
> in ntp.conf.
> --
> R. Kevin Oberman, Network Engineer
> Energy Sciences Network (ESnet)
> Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
> E-mail: oberman at es.net                  Phone: +1 510 486-8634
> Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751

I have no explanation, but one thing I am not clear about is whether the
other serves start responding after network connectivity is restored or
whether they respond but local remains the preferred peer.

Once the network is restored, does 'ntpq -p SERVER' work? 
-- 
R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman at es.net			Phone: +1 510 486-8634
Key fingerprint:059B 2DDF 031C 9BA3 14A4  EADA 927D EBB3 987B 3751



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