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

Martin Burnicki <martin.burnicki@meinberg.de> Fri, 08 January 2021 15:06 UTC

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To: Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de>, martin.burnicki=40meinberg.de@dmarc.ietf.org, mlichvar@redhat.com, emmanuel.fuste@thalesgroup.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: Fri, 08 Jan 2021 16:06:02 +0100
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Subject: Re: [Ntp] Antw: [EXT] Re: CLOCK_TAI (was NTPv5: big picture)
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Ulrich Windl wrote:
>>>> Martin Burnicki <martin.burnicki=40meinberg.de@dmarc.ietf.org> schrieb am
> 07.01.2021 um 16:55 in Nachricht
>> Miroslav Lichvar wrote:
>>> The best thing you can do on such an OS is to suspend the operation
>>> around leap second, the same thing as when using a leaping timescale.
> 
> Does "around the leap second" mean "until leap smear is complete" in case of
> leap smearing?

ntpd from ntp.org as a server returns "not synchronized" to clients from
one second before until one second after the leap second.

If a client with a 64 s or even longer poll interval happens to send a
request during this short moment, it receives a single response that it
just discards, and the next packet exchange works well again with the
"new" UTC timestamps after the leap second.

This usually doesn't hurt the client, and avoids that the client sees a
sudden huge 1 s offset if the leap second occurs in the middle of a
packet exchange.

This has been proposed by Miroslav some time ago and works very well.

Martin
-- 
Martin Burnicki

Senior Software Engineer

MEINBERG Funkuhren GmbH & Co. KG
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