[tcpm] Outline of diffs (was: I-D Action: draft-ietf-tcpm-accurate-ecn-26.txt)

tcpm list, Michael T (as doc shepherd),

A quick explanation for the two draft submissions (25 & 26) in quick 
succession...
Together they are intended to wrap up all the concerns from the recent WGLC.
* 25 wraps up all the editorial changes
* 26 wraps up all the technical and normative changes
I separated them, because the number of both types of changes would 
otherwise have made it harder to find the technical changes.

In the morning (PT), I'll give an outline of the main changes. But the 
diffs should help in the meantime.

Lastly, apologies for these submissions so close to the meeting on Thu. 
I'm afraid I was not in a position to be able to publish these drafts 
any earlier even though they were ready.

Bob

On 24/07/2023 08:49, internet-drafts@ietf.org wrote:
> A New Internet-Draft is available from the on-line Internet-Drafts
> directories. This Internet-Draft is a work item of the TCP Maintenance and
> Minor Extensions (TCPM) WG of the IETF.
>
>     Title           : More Accurate Explicit Congestion Notification (ECN) Feedback in TCP
>     Authors         : Bob Briscoe
>                       Mirja Kühlewind
>                       Richard Scheffenegger
>     Filename        : draft-ietf-tcpm-accurate-ecn-26.txt
>     Pages           : 70
>     Date            : 2023-07-24
>
> Abstract:
>     Explicit Congestion Notification (ECN) is a mechanism where network
>     nodes can mark IP packets instead of dropping them to indicate
>     incipient congestion to the endpoints.  Receivers with an ECN-capable
>     transport protocol feed back this information to the sender.  ECN was
>     originally specified for TCP in such a way that only one feedback
>     signal can be transmitted per Round-Trip Time (RTT).  Recent new TCP
>     mechanisms like Congestion Exposure (ConEx), Data Center TCP (DCTCP)
>     or Low Latency, Low Loss, and Scalable Throughput (L4S) need more
>     accurate ECN feedback information whenever more than one marking is
>     received in one RTT.  This document updates the original ECN
>     specification in RFC 3168 to specify a scheme that provides more than
>     one feedback signal per RTT in the TCP header.  Given TCP header
>     space is scarce, it allocates a reserved header bit previously
>     assigned to the ECN-Nonce.  It also overloads the two existing ECN
>     flags in the TCP header.  The resulting extra space is exploited to
>     feed back the IP-ECN field received during the 3-way handshake as
>     well.  Supplementary feedback information can optionally be provided
>     in two new TCP option alternatives, which are never used on the TCP
>     SYN.  The document also specifies the treatment of this updated TCP
>     wire protocol by middleboxes.
>
> The IETF datatracker status page for this Internet-Draft is:
> https://datatracker.ietf.org/doc/draft-ietf-tcpm-accurate-ecn/
>
> There is also an htmlized version available at:
> https://datatracker.ietf.org/doc/html/draft-ietf-tcpm-accurate-ecn-26
>
> A diff from the previous version is available at:
> https://author-tools.ietf.org/iddiff?url2=draft-ietf-tcpm-accurate-ecn-26
>
> Internet-Drafts are also available by rsync at rsync.ietf.org::internet-drafts
>
>
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-- 
________________________________________________________________
Bob Briscoe                               http://bobbriscoe.net/