So use PTP with a local source instead of NTP over the internet.

"On a local area network, [PTP] achieves clock accuracy in the sub-microsecond range"

https://en.wikipedia.org/wiki/Precision_Time_Protocol

I disagree that the problem the patent purports to solve is particularly difficult, given the technology that is already readily available (PTP, an OS with a high resolution clock, machines located in exchange data centers).