Re: [Ntp] Antw: [EXT] [Errata Verified] RFC5905 (5020)

[[e-mail]]

I think the errata is ok. Please consolidate 

 

Levine, J. (2011). Timing in telecommunications networks. Metrologia, 48(4), S203-S212. doi:Doi 10.1088/0026-1394/48/4/S12

Equation (3) with k=1/2.

 

Greetings

Dieter

 

-------------------------------------

Dr. Dieter Sibold

ISB - Informationssicherheitsbeauftragter

Physikalisch-Technische Bundesanstalt

The National Metrology Institute of Germany
Bundesallee 100
D-38116 Braunschweig

phone   [phone]
mobile  [phone]
email   [e-mail]
        [e-mail]

 

 

----- Ursprüngliche Nachricht -----
Von: "Steven Sommars" <[e-mail]>
Gesendet von: "ntp" <[e-mail]>
An: "Ulrich Windl" <[e-mail]>
CC: [e-mail], [e-mail], [e-mail], [e-mail], [e-mail], [e-mail], [e-mail], [e-mail], "The IESG" <[e-mail]>, "[e-mail]" <[e-mail]>
Betreff: Re: [Ntp] Antw: [EXT] [Errata Verified] RFC5905 (5020)
Datum: Do, 28. Jul 2022 10:19
 

I don't get it.

 

Theta is "the offset of B relative to A". The proposed revision is

   1/2 * [(T2-T1) + (T4-T3)] 

Example: Let's assume that B and A are exactly synced to UTC and that the network delay is 50msec in each direction.

    T2-T1 is the NTP mode 3 request delay (including network delay).    This gives 50 msec

    T4-T3 is the NTP mode 4 response delay (including network delay).   This gives 50 msec.

The proposed revision gives 100msec/2 = RTT/2, not the expected offset of zero.

 

The RFC5905 formula seems correct.

    theta = T(B) - T(A) = 1/2 * [(T2-T1) + (T3-T4)]

but might have been clearer had it been written:

    theta = T(B) - T(A) = 1/2 * [(T2-T1) - (T4-T3)]

 

 

On Thu, Jul 28, 2022 at 4:54 AM Ulrich Windl <[e-mail]> wrote:

>>> RFC Errata System <[e-mail]> schrieb am 27.07.2022 um
17:06 in
Nachricht <[e-mail]>:
> The following errata report has been verified for RFC5905,
> "Network Time Protocol Version 4: Protocol and Algorithms Specification".
>
> --------------------------------------
> You may review the report below and at:
> https://www.rfc-editor.org/errata/eid5020" rel="noreferrer nofollow" target="_blank">https://www.rfc-editor.org/errata/eid5020
>
> --------------------------------------
> Status: Verified
> Type: Technical
>
> Reported by: Ferenc Wágner <[e-mail]>
> Date Reported: 2017-05-15
> Verified by: Erik Kline (IESG)
>
> Section: 8
>
> Original Text
> -------------
> theta = T(B) - T(A) = 1/2 * [(T2-T1) + (T3-T4)]
>
> Corrected Text
> --------------
> theta = T(B) - T(A) = 1/2 * [(T2-T1) + (T4-T3)]

If that's wrong, RFC 1305 would be just as wrong, because it says (page 25 in
PDF):
((Ti−2 − Ti−3) + (Ti−1 − Ti)) / 2
,

>
> Notes
> -----
> The corresponding code line in A.5.1.1. agrees with this correction:
>
> offset = (LFP2D(r->rec - r->org) + LFP2D(r->dst - r->xmt)) / 2;
>
> taking Figure 7 into account:
>
> | org       | T1         | origin timestamp      |
> | rec       | T2         | receive timestamp     |
> | xmt       | T3         | transmit timestamp    |
> | dst       | T4         | destination timestamp |
>
> --------------------------------------
> RFC5905 (draft-ietf-ntp-ntpv4-proto-13)
> --------------------------------------
> Title               : Network Time Protocol Version 4: Protocol and
> Algorithms Specification
> Publication Date    : June 2010
> Author(s)           : D. Mills, J. Martin, Ed., J. Burbank, W. Kasch
> Category            : PROPOSED STANDARD
> Source              : Network Time Protocols
> Area                : Internet
> Stream              : IETF
> Verifying Party     : IESG
>
> _______________________________________________
> ntp mailing list
> [e-mail]
> https://www.ietf.org/mailman/listinfo/ntp" rel="noreferrer nofollow" target="_blank">https://www.ietf.org/mailman/listinfo/ntp



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