[ntp:questions] high precision tracking: trying to understand sudden jumps

Hal Murray hal-usenet at ip-64-139-1-69.sjc.megapath.net
Tue Apr 1 18:38:01 UTC 2008


>Yes, PTP can yield an accuracy better than 100 ns if both the NICs at the
>clients and the server support hardware timestamping of sent/received PTP
>packets.
>
>On the other hand, also *every* network node between the PTP endpoints has
>to be PTP-aware and compensate the packet delay it introduces, so you will
>probably only get full PTP accuracy in your local network where you have
>control over all the equipment.

Suppose I have PTP network adapters but vanilla switches and my
network is lightly loaded.

Can I filter out the delays in the switches by sending 10 packets
and throwing out the ones with long delays?  I'd expect the
timings to be a cluster around the case where there was no delay
in the switch and a tail for the ones that encountered some
delay.  I think it would be easy to filter out that tail.

-- 
These are my opinions, not necessarily my employer's.  I hate spam.




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