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Re: [Ntp] CLOCK_TAI (was NTPv5: big picture)

Martin Burnicki <martin.burnicki@meinberg.de> Wed, 06 January 2021 10:31 UTC

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To: Philip Prindeville <philipp@redfish-solutions.com>, Magnus Danielson <magnus@rubidium.se>
Cc: NTP WG <ntp@ietf.org>, Warner Losh <imp@bsdimp.com>
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From: Martin Burnicki <martin.burnicki@meinberg.de>
Organization: Meinberg Funkuhren GmbH & Co. KG, Bad Pyrmont, Germany
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Date: Wed, 06 Jan 2021 11:31:07 +0100
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Subject: Re: [Ntp] CLOCK_TAI (was NTPv5: big picture)
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Philip Prindeville wrote:
> 
>> On Jan 5, 2021, at 4:04 AM, Magnus Danielson <magnus@rubidium.se> wrote:
>>
>> The particular thread started out with an ambition to steer how kernel
>> implement things, that I think is outside the scope of the WG. What is
>> inside is that regardless of how it is implemented, the needed
>> definitions, information and similar is provided such that
>> implementations (the notion kernel and user space may actually be
>> completely irrelevant in some implementations) can reasonably be
>> implemented, both in clarity and consistency.
> 
> 
> I don’t agree.
> 
> It’s completely acceptable for the WG to mandate certain requirements like “must have RTC”, “RTC must be accurate to <= 16 ppm”, “must have persistent storage for storing […]”, etc.  Look at RFC-1122, 1123, and 1812…

Sorry, I disagree here.

There are lots of simple clients that don't have a RTC and simply get
the initial time via NTP.

Having a hard requirement for a battery buffered RTC chip would just
limit the number of scenarios where NTP can be used.

> Such a requirement was that the sysUpTime in MIB2 required a 100Hz (or better) clock.

It's OK that a specific application has such requirement, but I don't
think a protocol like NTP should have it.

Martin
-- 
Martin Burnicki

Senior Software Engineer

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