Re: [tcpm] I-D Action: draft-ietf-tcpm-rfc793bis-24.txt

Wesley Eddy <> Mon, 12 July 2021 19:05 UTC

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From: Wesley Eddy <>
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Date: Mon, 12 Jul 2021 15:03:02 -0400
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Subject: Re: [tcpm] I-D Action: draft-ietf-tcpm-rfc793bis-24.txt
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Sorry, one more thing to ask the working group ...

In a couple of places, Martin suggested changing "text" to "data".  I 
agree, this probably makes more sense to a modern reader and is merely 

Should we change that not just in a couple of places Martin noted, but 
across the board in the document?

On 7/12/2021 2:57 PM, Wesley Eddy wrote:
> This revision has changes resulting from Martin's AD review and 
> subsequent comments from Yuchung and Joe.
> A few things to specifically check over since I wasn't sure if the 
> thread totally converged on them, and they should be confirmed:
> (1) urgent pointer "receding"
> I think the key to understand is that the only time an application can 
> set this is when data is written, so it should not "recede" since you 
> can't write backwards.   There was already a paragraph saying:
>     To send an urgent indication the user must also send at least one
>     data octet.
> I'm not sure if this completely satisfies Martin's comment, but for 
> now, I added this sentence:
>    Note that because changes in the urgent pointer correspond
>     to data being written by a sending application, the urgent pointer
>     can not "recede" in the sequence space, but a TCP receiver should be
>     robust to invalid urgent pointer values.
> (2) PUSH check in SWS timer expiration
> I think Martin is right, and if the intention is that if the SWS timer 
> expires, it's okay to send, even if PUSH isn't set. This:
>     or if data is PUSHed and the override timeout occurs.
> was changed to:
>     or if the override timeout occurs.
> (3) unnecessary Step 4 for LISTEN state when SEGMENT ARRIVES
> Changed:
>           fourth other text or control
>              Any other control or text-bearing segment (not containing
>              SYN) must have an ACK and thus would be discarded by the ACK
>              processing.  An incoming RST segment could not be valid,
>              since it could not have been sent in response to anything
>              sent by this incarnation of the connection.  So, if this
>              unlikely condition is reached, the correct behavior is to
>              drop the segment and return.
> to:
>        fourth other data or control
>           This should not be reached.  Drop the segment and return.  Any
>           other control or data-bearing segment (not containing SYN) must
>           have an ACK and thus would have been discarded by the ACK
>           processing in the second step, unless it was first discarded by
>           RST checking in the first step.
> Although maybe if we agree that it's totally pointless to have, then 
> this "fourth" step can just be removed entirely.
> On 7/12/2021 2:48 PM, wrote:
>> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>> This draft is a work item of the TCP Maintenance and Minor Extensions WG of the IETF.
>>          Title           : Transmission Control Protocol (TCP) Specification
>>          Author          : Wesley M. Eddy
>> 	Filename        : draft-ietf-tcpm-rfc793bis-24.txt
>> 	Pages           : 108
>> 	Date            : 2021-07-12
>> Abstract:
>>     This document specifies the Transmission Control Protocol (TCP).  TCP
>>     is an important transport layer protocol in the Internet protocol
>>     stack, and has continuously evolved over decades of use and growth of
>>     the Internet.  Over this time, a number of changes have been made to
>>     TCP as it was specified in RFC 793, though these have only been
>>     documented in a piecemeal fashion.  This document collects and brings
>>     those changes together with the protocol specification from RFC 793.
>>     This document obsoletes RFC 793, as well as RFCs 879, 2873, 6093,
>>     6429, 6528, and 6691 that updated parts of RFC 793.  It updates RFC
>>     1122, and should be considered as a replacement for the portions of
>>     that document dealing with TCP requirements.  It also updates RFC
>>     5961 by adding a small clarification in reset handling while in the
>>     SYN-RECEIVED state.  The TCP header control bits from RFC 793 have
>>     also been updated based on RFC 3168.
>>     RFC EDITOR NOTE: If approved for publication as an RFC, this should
>>     be marked additionally as "STD: 7" and replace RFC 793 in that role.
>> The IETF datatracker status page for this draft is:
>> There is also an htmlized version available at:
>> A diff from the previous version is available at:
>> Internet-Drafts are also available by anonymous FTP at:
>> _______________________________________________
>> tcpm mailing list