Magnus Danielson wrote:
On 18/03/14 10:17, Martin Burnicki wrote:
We have mades some tests and found that NTP can yield the same accuracy
as NTP if also hardware timestamping of NTP packets is supported on all
nodes, similar as for PTP.
In fact this isn't surprising, is it?
No, it's not. NTP is being perceived to be "software timestamping" but
nothing prohibits you from doing it in hardware. Similarly can you
implement PTP with software time-stamping (with shitty performance).
As I mentioned in a different posting, even if you use hardware
timestamping with NTP you are out of luck for highest accuracy since
there are (AFAIK) no switches which have been designed to timestamp NTP
packets.
And even if there were, the next question is how to get the measured
latency compensation parameters to the client without breaking the
existing protocol?
Maybe this would be an interesting approach for NTP v5.
Martin
--
Martin Burnicki
Meinberg Funkuhren
Bad Pyrmont
Germany
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