Re: NTP Sync Issue Across Tata (Europe)

["Forrest Christian (List Account)" <lists () packetflux com>]

Depends on how synchronized you need to be.

In the context of running airgapped:

 A rubidium oscillator or Chip Scale Atomic Clock is in the price range you
quote.  However, these can drift enough that you should occasionally
synchronize with a reference time source.  This is to ensure continued
millisecond accuracy.  Of course it all depends on how much drift you'll
tolerate, and if you're OK with being within a second, then a rubidium
might be ok.

Caesium oscillators which have much lower drift are in the $30K-50K range.
These would require significantly less frequent synchronization, but are
definitely not a few thousand dollars.

Note that these are both just oscillators and they need additional support
hardware to be able to be queried by NTP.  Or stated differently,  they
still need a NTP server.  Yes, there are products out there which integrate
everything in one box at an additional cost.






On Mon, Aug 7, 2023, 11:02 PM Masataka Ohta <
mohta () necom830 hpcl titech ac jp> wrote:

> Forrest Christian (List Account) wrote:
>
> > In the middle tends to be a more moderate solution which involves a mix
> of
> > time transmission methods from a variety of geographically and/or network
> > diverse sources.  Taking time from the public trusted ntp servers and
> > adding lower cost GPS receivers at diverse points in your network seems
> > like a good compromise in the middle.  That way,  only coordinated
> attacks
> > will be successful.
>
> Instead, just rely on atomic clocks operated by you. They are not
> so expensive (several thousand dollars) and should be accurate
> enough without adjustment for hundreds of years. There can be no
> coordinated attacks. They may be remotely accessed through
> secured NTP.
>
>                                         Masataka Ohta