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

[Bob Jonkman]

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As an aside, I would love to see a presentation on keeping time in
sync on Linuxen, with a deep dive into the innards of NTP.  Sounds
like GTALUG has the talent pool for such a presentation...

- --Bob.



On 16/03/15 12:33 PM, Mike wrote:
> 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 --- Talk Mailing List talk at gtalug.org 
>>> http://gtalug.org/mailman/listinfo/talk
>>> 
>> 
>> 
>> --- Talk Mailing List talk at gtalug.org 
>> http://gtalug.org/mailman/listinfo/talk
>> 
>> 
> 
> 
> 
> --- Talk Mailing List talk at gtalug.org 
> http://gtalug.org/mailman/listinfo/talk
> 
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