> On Nov 28, 2016, at 01:01, Miroslav Lichvar <mlich...@redhat.com> wrote:
> 
> If you are sure the error doesn't come from the switch, I suspect it's
> a HW or driver issue. It seems the drivers need to have some
> timestamping-specific magic. Look at the following commit for
> instance.
> 
> http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=0066c8b6f4050d7c57f6379d6fd4535e2f267f17


This changes is why I asked what kernel version you were testing with on your 
I210. Intel documents these time offsets in the spec sheet for the I210. There 
are no offsets listed for the I211 or I354.


> I'd suggest to send a detailed report to the intel-wired-lan list and
> see if anyone has any suggestions on what could be wrong.



Before I try and make a case to the driver and hardware folk, I think I need to 
be able to explain how stamps on both two linux systems can sometimes be in 
agreement with stamps on the second interface and sometimes not. Given just the 
following two tests:

 igb0 @ 1Gb; igb3 @ 100Mb direct connect: 192.168.230.245 shows offset of 
+1230ns
 igb0 @ 100Mb; igb3 @ 100Mb, direct connect: 192.168.230.245 shows no offset

I cannot explain why the two linux systems do not disagree on stamps in the 
second test. Can you think of something that the driver or hardware could be 
doing that would explain that?

Denny


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