[ntp:questions] Looking for a NTP stratum 2 appliance
fmeyer at obs-besancon.fr
Mon May 29 08:24:50 UTC 2017
On Sat, 27 May 2017, Matthew Huff wrote:
> 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.
I jump in the discussion, you can probably get out of problems just
by adding some infos in your QMS, detailing why you need (or not)
to check the UTC(NIST) - GPSTime traceability, and how you achieve
that, if needed ; since NIST declares it provides this information (with a
24 hour delay), you can rely on this to setup a more or less automatic
online check from the NIST website (that would prove to be technically
useless since offests will stubbornly be 0 as far as milliseconds are concerned).
Instead of useless equipment, it is a one time documentation job, a daily
automated data retrieval and check with email alarm for example.
Arguing against possible objections to the 24 hour delay is left to the reader :)
If you do need a proven, real time access to UTC(whatever) <5ms, then it might get
a bit muddier.
(The problem is not between UTC(NIST) and UTC(USNO), both are
equivalently traceable to SI ; the problem is with GPS Time,
that is not UTC(USNO) and not traceable)
> Matthew Huff | 1 Manhattanville Rd
> Director of Operations | Purchase, NY 10577
> OTA Management LLC | Phone: 914-460-4039
> aim: matthewbhuff | Fax: 914-694-5669
>> -----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
>> 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
>> 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
>> offset between UTC(NIST) and UTC(USNO) so they can be considered
>> instances of UTC in the US.
>> questions mailing list
>> questions at lists.ntp.org
> questions mailing list
> questions at lists.ntp.org
François Meyer Tel : (+33) 3 81 66 69 27 Mob : 6 27 28 56 83
Observatoire de Besancon - BP1615 - 25010 Besancon cedex - FRANCE
Institut UTINAM * Universite de Franche-Comte * CNRS UMR 6213 ***
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