[ntp:questions] Looking for a NTP stratum 2 appliance

Matthew Huff mhuff at ox.com
Sat May 27 11:01:12 UTC 2017


I'll pass this along to our auditors, but I doubt it will make any difference. For another example, we had to block all access to removable USB drives because of possible transfer of unauthorized data, but DropBox was okay. We have to archive all IM messages, but not phone calls. /boggle

Again, the goal is to satisfy auditors, not do the right thing. But either way, we are synced to two S1 clocks on all of our ntp clients which have their source as GPS. So we are correct, either way.

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> -----Original Message-----
> From: questions [mailto:questions-bounces+mhuff=ox.com at lists.ntp.org]
> On Behalf Of Paul
> Sent: Saturday, May 27, 2017 1:32 AM
> To: Harlan Stenn <stenn at ntp.org>
> Cc: NTP Questions <questions at lists.ntp.org>
> Subject: Re: [ntp:questions] Looking for a NTP stratum 2 appliance
> 
> On Fri, May 26, 2017 at 10:33 PM, Harlan Stenn <stenn at ntp.org> wrote:
> 
> > NIST doesn't control GPS.  That's done by USNO and the USAF.
> >
> 
> This is true(ish)* but irrelevant.  NIST defines traceability to NIST
> and
> GPS can be a component of UTC(NIST) traceability.
> 
> More importantly the premise of this issue is incorrect (if it has been
> properly presented).  If I have an S2 clock peering both with a GPS
> disciplined S1 clock and a NIST clock via NTP then "apparent" errors
> ("drift") are measurements of network instability not variance from
> UTC(NIST).  E.g. this line:
> 
>  time-d.nist.gov .NIST.           1 u   35  512    7   48.037    1.714
> 2.137
> 
> does not mean this clock has a 1.7ms offset and 2.1ms of jitter with
> respect to UTC(NIST).
> 
> Since NIST specs the NTP error O(50ms) due to network issues it's
> insufficient for the stated need in any case.
> 
> *NIST publishes the delta and the two groups work to maintain
> constrained
> offset between UTC(NIST) and UTC(USNO) so they can be considered
> equivalent
> instances of UTC in the US.
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