[GTALUG] NTP's Fate Hinges On 'Father Time' - InformationWeek

[Mike]

PTP at IP (layer 3) still needs hardware-based (PHY or MAC level)
timestamping in order to achieve O(nanoseconds) and O(ppb) performance in
phase and frequency.  The best performance is achieved with this support at
every link that time sync data traverses.

Telco nerds use Synchronous Ethernet besides...

Mike

On Mon, Mar 16, 2015 at 8:16 AM, David Thornton <northdot9 at gmail.com> wrote:

> "There is PTP support in Linux, but you need an Ethernet card with the
> right timestamping feature plugged into a switch that does PTP too."
>
> You can do PTP over IP but I understand you can also deploy "dedicated"
> networks that JUST do PTP ( no ip ).
>
> It is the dedicate nets you are talking about ?
>
> The sexiest PTP hardware I've seen is the solarflare stuff.
>
> David
>
>
>
>
> On Sun, Mar 15, 2015 at 5:58 PM, Anthony de Boer <adb at adb.ca> wrote:
>
>> Stewart C. Russell wrote:
>> > On 2015-03-14 10:09 PM, David Thornton wrote:
>> > > My finance client's use ptp not ntp.
>> >
>> > Is PTP particularly hard to use? It looks like an ISO standard, so will
>> > likely be fiddly but complete.
>>
>> Accuracy numbers in PTP are measured in nanoseconds, while the NTP world
>> talks milliseconds.  So if you have that sort of accuracy requirement
>> (power system phasors, etc) you probably want PTP with the appropriate
>> dedicated hardware, while garden-variety Unix admins just want log
>> records to show up with the right second.
>>
>> There is PTP support in Linux, but you need an Ethernet card with the
>> right timestamping feature plugged into a switch that does PTP too.
>>
>> Meanwhile, ntpd is getting a bit long in the tooth[0] and the ntimed
>> project looks interesting.
>>
>> [0] "support for hardware clocks EBay has never heard of"
>>
>> --
>> Anthony de Boer
>> ---
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>>
>
>
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