One-Way-Delay from NTP

NTP skews the clock, this creates problems for measurement.

General network measurement community wisdom says "Turn NTP off"

Info exchange provides enough information to allow the effect of NTP to be understood at the measurement system

Introduces the possibility of using NTP to do one-way delay 
we know the bounds of NTP's adjustment of the clock

ntp_adjtime system call reports offset from real time, with error bounds

this information is useful for adjusting to real time with information request packets

if the information is reported with an excessive error, we know not to include that particular clock for that particular measurement