Some Congestion Experienced in TCP
draft-grimes-tcpm-tcpsce-00

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Last updated 2019-07-08
Replaces draft-grimes-tcpmwg-tcpsce
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TCP Maintenance and Minor Extensions                         R.W. Grimes
Internet-Draft                                                  P. Heist
Intended status: Standards Track                             8 July 2019
Expires: 9 January 2020

                   Some Congestion Experienced in TCP
                      draft-grimes-tcpm-tcpsce-00

Abstract

   This memo classifies a TCP code point ESCE ("Echo Some Congestion
   Experienced") for use in feedback of IP code point SCE ("Some
   Congestion Experienced").

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on 9 January 2020.

Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   provided without warranty as described in the Simplified BSD License.

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Table of Contents

   1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  TCP Receiver  . . . . . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Single ACK implementation . . . . . . . . . . . . . . . .   3
     4.2.  Simple Delayed ACK implementation . . . . . . . . . . . .   3
     4.3.  Dithered Delayed ACK implementation . . . . . . . . . . .   3
   5.  TCP Sender  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   6.  Related Work  . . . . . . . . . . . . . . . . . . . . . . . .   4
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   10. Normative References  . . . . . . . . . . . . . . . . . . . .   4
   11. Informative References  . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   [RFC2119] and [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

2.  Introduction

   This memo reclassifies the former TCP NS ("Nonce Sum") codepoint as
   ESCE.

   This memo limits its scope to the redefinition of the TCP NS
   codepoint as ESCE, with a few brief illustrations of how it may be
   used.

   SCE provides early and proportional feedback to the CC (congestion
   control) algorithms for transport protocols, including but not
   limited to TCP.  The [sce-repo] is a Linux kernel modified to support
   SCE, including:

   *  Enhancements to Linux's Cake (Common Applications Kept Enhanced)
      AQM to support SCE signaling

   *  Modifications to the TCP receive path to reflect SCE signals back
      to the sender

   *  The addition of three new TCP CC algorithms that modify the

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      originals to add SCE support: Reno-SCE, DCTCP-SCE and Cubic-SCE
      (work in progress as of this writing)

3.  Background

   [I-D.morton-tsvwg-sce] defines the SCE codepoint and [RFC8311]
   (section 3) obsoletes the NS codepoint making it avaliable valiable
   for use.

4.  TCP Receiver

   The mechanism defined to feed back SCE signals to the sender
   explicitly makes use of the ESCE ("Echo Some Congestion Experienced")
   code point in the TCP header.

4.1.  Single ACK implementation

   Upon receipt of a packet an ACK is immediatly generated, the SCE
   codepoint is copied into the ESCE codepoint of the ACK.  This keeps
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