[Ntp] Antw: Re: Leap second

"Ulrich Windl" <Ulrich.Windl@rz.uni-regensburg.de> Fri, 24 January 2020 09:00 UTC

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Date: Fri, 24 Jan 2020 10:00:35 +0100
From: Ulrich Windl <Ulrich.Windl@rz.uni-regensburg.de>
To: "ntp@ietf.org" <ntp@ietf.org>, Hal Murray <hmurray@megapathdsl.net>
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Subject: [Ntp] Antw: Re: Leap second
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>>> Hal Murray <hmurray@megapathdsl.net> schrieb am 24.01.2020 um 00:52 in
Nachricht <20200123235232.BB54440605C@ip-64-139-1-69.sjc.megapath.net>:

> Warner Losh said:
>> NTP timestamp repeats the last second of the day. Once without the leap
bit
>> set and then again with it set. 
> 
> Which bit is that?  I don't know of a single "leap bit" in the header.
> 
> There is a 2 bit header field with: normal (no leap), and add+del (leap 
> pending) states.  The 4th state is used for non‑in‑sync.  Assuming you meant

> "bits" rather than bit, then the on‑off is backwards.  I expect it to be 
> sending leap‑pending for most of the day, then send normal (no leap‑pending)

> for the repeated last second of the day.
> 
> ‑‑‑‑‑‑‑‑
> 
> I just looked at some code and found:
>                 if (leap_sec_in_progress) {
>                         /* always send "not sync" */
>                         xmt_leap = LEAP_NOTINSYNC;
>                 }

I wonder whether this makes much sense. Probably easy to implement, but maybe
the server just should not respond during the leap second. Preferrable it
should just sent the "correct" response.

> 
> Looks like it is responding with "I don't know" during the extra second. 
> (but 
> I didn't check carefully)
> 
> 
> ‑‑ 
> These are my opinions.  I hate spam.
> 
> 
> 
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