Re: [dhcwg] [ntpwg] Fwd: New Version Notification for draft-ogud-dhc-udp-time-option-01.txt

Harlan Stenn <stenn@ntp.org> Mon, 02 December 2013 21:34 UTC

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From: Harlan Stenn <stenn@ntp.org>
To: Warner Losh <imp@bsdimp.com>
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References: <20131202044734.B78E0406060@ip-64-139-1-69.sjc.megapath.net> <529C1A31.2080900@ntp.org> <258D838F-F4BA-45D2-AA41-BB05E3AB147C@ogud.com> <529CA616.3010402@ntp.org> <19575403-444E-4CBA-8818-5F46328787AE@bsdimp.com> <E1VnZdi-0000fA-CY@stenn.ntp.org> <220ED02D-AE73-436F-A81F-BDF54611173B@bsdimp.com>
Comments: In-reply-to Warner Losh <imp@bsdimp.com> message dated "Mon, 02 Dec 2013 13:09:06 -0700."
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Date: Mon, 02 Dec 2013 21:32:13 +0000
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Cc: Harlan Stenn <stenn@ntp.org>, Hal Murray <hmurray@megapathdsl.net>, Bernie Volz <volz@cisco.com>, NTP Working Group <ntpwg@lists.ntp.org>, Ted Lemon <ted.lemon@nominum.com>, "dhcwg@ietf.org WG" <dhcwg@ietf.org>
Subject: Re: [dhcwg] [ntpwg] Fwd: New Version Notification for draft-ogud-dhc-udp-time-option-01.txt
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Warner Losh writes:
> On Dec 2, 2013, at 12:58 PM, Harlan Stenn wrote:
>> It's actually fuzzier than that, and this situation (which is handled
>> differently with ntpd under unix, ntpd under windows, and on systems
>> that "smear" the leap second over a longer period) is one of the
>> cases handled by the General Timestamp API project at Network Time
>> Foundation, described at http://nwtime.org/projects/timestamp-api/ .
> 
> Actually, in all those cases it is within a second of the 'real' time,
> hence specifying that it should be one second or the other seems
> appropriate. The timestamp APIs are for sub-second resolution, while the
> time_t in this protocol has only a second resolution... The main point
> is that it should be (a) specified to be what's going to most likely
> happen (or keep bounds on the error)  and (b) something sane that
> doesn't introduce errors > tolerance of the protocol. Having it be
> completely unspecified is a mistake, since -1 could be returned...

I'd suspect that usually 1 second will be the ballpark, but it's pretty
easy to find situations where the system clock is out by more than that.

I mention the General Timestamp API because that effort is looking at
use cases like this one from a larger persepective.

H