[ntp:questions] Issues trying to sync to NIST public servers

Greg.Dowd at microchip.com Greg.Dowd at microchip.com
Mon Feb 4 20:01:45 UTC 2019

I'm not certain I understand the traceability concern as stated since they are both traceable to UTC.  NIST servers are traceable to UTC(NIST) while GPS is traceable to UTC(USNO).  It is true that NIST is charged with distributing time to commercial entities in the US (via WWVB/NTP/Popcorn/etc) so that is probably where the legal requirement comes in.  But as you say, I think you can make good arguments for have a more diverse (and robust) synchronization network with NIST servers being an element of it.  Then, with proper logging, it should be possible to show the clock reference as validated by NIST server queries while not having to always be directly synchronized to them.  Most servers are in free fall all the time anyway with just the occasional ping to the servers.  At least from a sync point of view.

Greg Dowd
Principal Engineer, FTD
3870 N. First St. | San Jose | CA 95134 | USA
Office: 408.964.7643
Email: greg.dowd at microchip.com
Company Website:  www.microsemi.com

-----Original Message-----
From: questions [mailto:questions-bounces+greg.dowd=microsemi.com at lists.ntp.org] On Behalf Of François Meyer
Sent: Saturday, February 2, 2019 3:40 PM
To: questions at lists.ntp.org
Subject: Re: [ntp:questions] Issues trying to sync to NIST public servers


Yes, the main reason behind the requirement is probably the traceability to UTC of the stratum 0 used by the server : NIST servers are traceable to UTC, which is (formally) not the case for a server with a GNSS as stratum 0.

In case NIST servers are hard to reach, a metrologically defendable fallback could be to use ntp servers from another national metrology institute which would provide the same traceability to UTC.

From the US, servers operated by the NRC in Canada is the most sensible (geographically speaking) option, and those servers have the same traceability status as NIST servers.


Just log the reason why you pick a server outside the US, locate and log the page on the NRC site stating the traceability to UTC of their time servers and Bob's your uncle ; thats enough to prove that you have taken the issue seriously and have taken the appropriate steps to ensure both your requirements and the traceability concern.

In Europe, picking a server operated by for example PTB in Germany, OP (Syrte) in France, NPL in the UK and so on would do the job.

On Fri, 1 Feb 2019, Jason Rabel wrote:

>> Yes, this is a common PITA. FINRA and/or SEC getting onto you?
>> They are still "defining" the regulation, but the current idea is rather silly.
>> Many of the NIST servers are run out of the University of Colorado 
>> and are single home with CenturyLink. Congestion and/or other network 
>> issues causes false alarms all the time.
> I don't know anything about the financial regulations, but what about 
> having a local GNSS or cellular based S1 NTP (or PTP) server? You will 
> gain an order of magnitude in accuracy syncing to a LAN source vs 
> traversing the Internet. Or possibly using the USNO NTP servers? I 
> suppose if it *has* to be traceable to NIST (which operates 
> independently of USNO/GPS) you could get a WWVB based NTP server. NIST 
> & USNO are generally less than 10 ns difference from each other, which 
> for NTP over ethernet the best you are going to get is in the ms range 
> so it's technically a non-issue.
>> IMHO, if FINRA is going to require something like that, then NIST 
>> should provide hardened NTP/PTP services at major peering/colocation facilities.
> Or use existing facilities at other major universities around the 
> country that could also benefit from having extra local NIST-synced 
> atomic standards.
> I've often wondered why they don't have multiple network providers at 
> their two existing facilities, having a single point of failure seems 
> awfully ironic seeing as how they have dozens of atomic clocks and 
> servers in the facility... lol.
> Though one has to remember this is also a very tiny part of overall 
> NIST. IIRC last time I saw NIST's 2019 budget figures they were taking 
> a pretty sizable cut in funding across the board, so expanding 
> services is probably out of the question unless it's deemed critical 
> for national security or something (Which I would think would still 
> fall under USNO & GPS before NIST).
> Jason
> _______________________________________________
> questions mailing list
> questions at lists.ntp.org
> http://lists.ntp.org/listinfo/questions

François Meyer
questions mailing list
questions at lists.ntp.org

More information about the questions mailing list