[time-nuts] NTP stratum 1 appliances with different (GPS, etc) cores...

Robert Seastrom rs-lists at seastrom.com
Mon Mar 9 16:31:46 EDT 2015

Hi folks,

Had a recent requirement at $DAYJOB to give our NTP architecture a good swift kick in the pants.  High precision is not a particular requirement (1 ms is more than adequate) but high reliability is.  I'm about done with explaining the difference between the two to people internally who don't get it.  :-(

Unfortunately, these days it's impossible to get sufficient out-of-band sources for stratum 1 clocks unless we're building our own constellation of primary frequency standards (Not Gonna Happen).  So I definitely intend to have our stratum 2 clocks (which customer and production devices will be pointing at) chiming off of plenty of off-site stuff too, hopefully things that are connected physically to a diverse set of primary sources (i.e. not gps or wwvb)

This approach would probably be fine for our internal consumption, frankly, considering our need for reliability but not supreme accuracy.  But there's still a desire internally to run a set of stratum 1 radio clocks.  In the course of this discussion, I invoked a particularly nasty "conspiracy" that happened back in 2002 wherein every TrueTime NTS-100 (which were extremely popular in those days) simultaneously decided that it was 20 years in the future and warped the time.  That's not the only case of devices losing their cookies; I seem to recall a problem with certain Motorola cores having an issue with leap seconds.

Anyway, I couldn't keep my mouth shut and suggested that at the very least, trying for multiple vendors (we have a strong preference for appliancey stuff here due to internal fiefdoms, ownership issues, and balkanization typical of a Fortune 200 company) with different GPS cores would be a really fine plan.

So of course, now it's my job to come up with proper nominees for this list.  Any suggestions would be greatly appreciated.  Hopefully someone's already done the legwork for this.  I will likely send this same request to the ntp dev list...



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