[ntp:questions] IEEE 1588 (PTP) at the nanosecond level?

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Tue Mar 18 23:20:42 UTC 2014


Magnus Danielson wrote:> 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).
>
> Doing HNTP makes NTP match up against PTPv1 to some degree,
>  but PTP then pulls out the explicit means to make PTP-aware
>  transparent clocks to correct for delays, cancelling some
>  of the asymmetry.
> You could do NTP with PTP 2-step processing,
>  but what we would call such a bastard would be an
>  interesting thing, NPTP?

Why not just NTP with a PTP RefClock Driver?

People Already Run (& sell) Appliances that are both
  PTP & NTP servers {which doesn't seem like it should be too hard};

 The question would be, which is disciplining the Appliance?

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