[tcpm] Fwd: [Technical Errata Reported] RFC0793 (4785)

"Mirja Kuehlewind (IETF)" <ietf@kuehlewind.net> Wed, 24 August 2016 23:21 UTC

From: "Mirja Kuehlewind (IETF)" <ietf@kuehlewind.net>
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
Date: Thu, 25 Aug 2016 01:21:02 +0200
References: <20160820132955.49560B80EE3@rfc-editor.org>
To: "tcpm@ietf.org Extensions" <tcpm@ietf.org>
Message-Id: <471798EE-293E-44E6-A7A3-EAB2ACF6CAEC@kuehlewind.net>
Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\))
Archived-At: <https://mailarchive.ietf.org/arch/msg/tcpm/7-7Ty-gp6hCdQgj2J5OQ3X03f_k>
Subject: [tcpm] Fwd: [Technical Errata Reported] RFC0793 (4785)
Precedence: list

FYI.

> Anfang der weitergeleiteten Nachricht:
> 
> Von: RFC Errata System <rfc-editor@rfc-editor.org>
> Betreff: [Technical Errata Reported] RFC0793 (4785)
> Datum: 20. August 2016 um 15:29:55 MESZ
> An: iesg@ietf.org
> Kopie: sanjeev.ranot.81@gmail.com, rfc-editor@rfc-editor.org
> 
> The following errata report has been submitted for RFC0793,
> "Transmission Control Protocol".
> 
> --------------------------------------
> You may review the report below and at:
> http://www.rfc-editor.org/errata_search.php?rfc=793&eid=4785
> 
> --------------------------------------
> Type: Technical
> Reported by: Sanjeev Ranot <sanjeev.ranot.81@gmail.com>
> 
> Section: 3.9  p. 72
> 
> Original Text
> -------------
> 
> 
> If the ACK is a duplicate
> (SEG.ACK < SND.UNA), it can be ignored.
> 
> Corrected Text
> --------------
> If the ACK is a duplicate
> (SEG.ACK =< SND.UNA), it can be ignored except when equality is met, 
> then window should be updated. This can happen when there are 
> segments in flight but the receiver shrinks its RCV.BUF to drop all 
> of them and send an ACK carrying zero window update. Upon its 
> arrival at the sending TCP, condition SND.UNA = SEG.ACK is met and 
> we must update SND.WND <- 0. Then sender starts persist timer for 
> sending zero-window probes [Ref. RFC 1122 Section 4.2.2.17, page 92]
> 
> 
> 
> 
> 
> Notes
> -----
> The condition is corrected as Duplicate ACK in 
> RFC 1122, Section 4.2.2.20 (g) p. 94. Accordingly old text must be 
> modified and new text should also be present to support the corrected 
> condition in RFC 793. 
> 
> This is one case where duplicate acknowledgment cannot be ignored. i.e. 
> when SEG.ACK == SND.UNA and advertised window in the incoming ACK is 0
> in which case sender needs to :
> 1. update window
> 2. start persist timer
> 3. send zero window probe segments. 
> 
> 
> Note:
> Such ACKs should not be called as duplicates as it fails condition (e) 
> of definition of "DUPLICATE ACKNOWLEDGMENT" in Ref 5681 Section 2, pg 4
> 
> Instructions:
> -------------
> This erratum is currently posted as "Reported". If necessary, please
> use "Reply All" to discuss whether it should be verified or
> rejected. When a decision is reached, the verifying party (IESG)
> can log in to change the status and edit the report, if necessary. 
> 
> --------------------------------------
> RFC0793 (no draft string recorded)
> --------------------------------------
> Title               : Transmission Control Protocol
> Publication Date    : September 1981
> Author(s)           : J. Postel
> Category            : INTERNET STANDARD
> Source              : Legacy
> Area                : Legacy
> Stream              : IETF
> Verifying Party     : IESG
>

[tcpm] Fwd: [Technical Errata Reported] RFC0793 (… Mirja Kuehlewind (IETF)
Re: [tcpm] Fwd: [Technical Errata Reported] RFC07… Wesley Eddy