I'm no NTP expert so I'm not sure what it does differently, but the more detailed paper is at http://research.google.com/archive/spanner.html
It would be interesting to have more details, since that article makes aTed Cabeen <ted@cabeen.org> writes:
> Interesting article on how Google has moved beyond NTP, with a mention
> of last year's leap second:
> http://www.wired.com/wiredenterprise/2012/11/google-spanner-time/
lot of Google not using NTP and then proceeds to describe a network
protocol that sounds exactly like NTP, down to how it distributes stratum
zero clock sources to other systems in the same data center. So it's not
clear exactly what they changed.
--
Russ Allbery (rra@stanford.edu) <http://www.eyrie.org/~eagle/>