On the offset issue… one of the benefits of having so many ports, and several 
of hardware based NTP units (thanks Leo/Anthony!) is that I have been able to 
replicate the issue by connecting serval ports directly from host to host with 
and without an intervening switch. I’ve also been able to test different 
chipsets. The short version of all the tests is that there is clear asymmetry 
with hardware timestamps. Based on research and the fact that the asymmetry 
varies with chipset, my best guess is that the hardware tx/rx timestamps are 
incorrect and need compensation in the driver. The 4.8.X kernel introduced 
compensation for the i210, but not for the i211 or the i354 (which I am testing 
with). I have a query into the Intel folk about this and will let you know what 
they say.

Denny


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