Re: [tcpm] 793bis ready to go?

Markku Kojo <kojo@cs.helsinki.fi> Tue, 16 February 2021 14:12 UTC

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Date: Tue, 16 Feb 2021 16:12:50 +0200 (EET)
From: Markku Kojo <kojo@cs.helsinki.fi>
To: Michael Scharf <Michael.Scharf@hs-esslingen.de>
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Subject: Re: [tcpm] 793bis ready to go?
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The CC test looks good. Just two minor things: one editorial and another 
small addition to address exponential backoff more accurately and 
correctly. See inline.

On Mon, 8 Feb 2021, Michael Scharf wrote:

> Dear all,
>
> draft-ietf-tcpm-rfc793bis-20 has been submitted recently. According to Wes, all WGLC feedback should be reflected in this version. A link to a complete diff can be found below.
>
> During WGLC, there has been quite some discussion on the exact wording on congestion control. The suggested text in version -20 is copied below:
>
> 3.7.2.  TCP Congestion Control
>
>   RFC 2914 [7] explains the importance of congestion control for the
>   Internet.
>
>   RFC 1122 required implementation of Van Jacobson's congestion control
>   algorithms slow start with congestion avoidance together with

Here

  "SS with CA together with ..."

reads a bit odd to me. But not sure as a non-native speaker. Would it 
possibly read better if changed to(?):

  "algorithms slow start and congestion avoidance together with
   exponential back-off ..."

OR:

   "algorithms slow start, congestion avoidance, and exponential
    back-off ..."

>   exponential back-off for successive RTO values for the same segment.
>   RFC 2581 provided IETF Standards Track description of slow start and
>   congestion avoidance, along with fast retransmit and fast recovery.
>   RFC 5681 is the current description of these algorithms and is the
>   current Standards Track specification providing guidelines for TCP
>   congestion control.  RFC 6298 describes exponential back-off of RTO
>   values, including keeping the backed-off value until a subsequent
>   segment with new data has been sent and acknowledged.

It would be useful to make the last sentence unambiguous as per Karn's 
original specification:

   "segment with new data has been sent and acknowledged without
    retransmission."

Thanks,

/Markku

>   A TCP endpoint MUST implement the basic congestion control algorithms
>   slow start, congestion avoidance, and exponential back-off of RTO to
>   avoid creating congestion collapse conditions (MUST-19).  RFC 5681
>   and RFC 6298 describe the basic algorithms on the IETF Standards
>   Track that are broadly applicable.  Multiple other suitable
>   algorithms exist and have been widely used.  Many TCP implementations
>   support a set of alternative algorithms that can be configured for
>   use on the endpoint.  An endpoint may implement such alternative
>   algorithms provided that the algorithms are conformant with the TCP
>   specifications from the IETF Standards Track as described in RFC
>   2914, RFC 5033 [10], and RFC 8961 [15].
>
>   Explicit Congestion Notification (ECN) was defined in RFC 3168 and is
>   an IETF Standards Track enhancement that has many benefits [50].
>
>   A TCP endpoint SHOULD implement ECN as described in RFC 3168 (SHLD-
>   8).
>
> As document shepherd I ask everybody - specifically all TCPM contributors who have commented on congestion control - to carefully review this proposed wording within the next few days. If there are any issues with this suggested resolution of the WGLC, please speak up!
>
> If the TCPM working group is fine with version -20, 793bis would be ready to go.
>
> Thanks
>
> Michael
>
>
> -----Original Message-----
> From: I-D-Announce <i-d-announce-bounces@ietf.org> On Behalf Of internet-drafts@ietf.org
> Sent: Thursday, January 21, 2021 7:02 PM
> To: i-d-announce@ietf.org
> Cc: tcpm@ietf.org
> Subject: I-D Action: draft-ietf-tcpm-rfc793bis-20.txt
>
>
> 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-20.txt
> 	Pages           : 110
> 	Date            : 2021-01-21
>
> 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:
> https://datatracker.ietf.org/doc/draft-ietf-tcpm-rfc793bis/
>
> There are also htmlized versions available at:
> https://tools.ietf.org/html/draft-ietf-tcpm-rfc793bis-20
> https://datatracker.ietf.org/doc/html/draft-ietf-tcpm-rfc793bis-20
>
> A diff from the previous version is available at:
> https://www.ietf.org/rfcdiff?url2=draft-ietf-tcpm-rfc793bis-20
>
>
> Please note that it may take a couple of minutes from the time of submission
> until the htmlized version and diff are available at tools.ietf.org.
>
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
>
>
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