ECN++: Adding Explicit Congestion Notification (ECN) to TCP Control Packets
draft-bagnulo-tcpm-generalized-ecn-04

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Last updated 2017-05-19
Replaces draft-bagnulo-tsvwg-generalized-ecn
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Network Working Group                                         M. Bagnulo
Internet-Draft                                                      UC3M
Intended status: Experimental                                 B. Briscoe
Expires: November 20, 2017                           Simula Research Lab
                                                            May 19, 2017

  ECN++: Adding Explicit Congestion Notification (ECN) to TCP Control
                                Packets
                 draft-bagnulo-tcpm-generalized-ecn-04

Abstract

   This document describes an experimental modification to ECN when used
   with TCP.  It allows the use of ECN on the following TCP packets:
   SYNs, pure ACKs, Window probes, FINs, RSTs and retransmissions.

Status of This Memo

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   Copyright (c) 2017 IETF Trust and the persons identified as the
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Bagnulo & Briscoe       Expires November 20, 2017               [Page 1]
Internet-Draft                    ECN++                         May 2017

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Motivation  . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Experiment Goals  . . . . . . . . . . . . . . . . . . . .   4
     1.3.  Document Structure  . . . . . . . . . . . . . . . . . . .   5
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   3.  Specification . . . . . . . . . . . . . . . . . . . . . . . .   6
     3.1.  Network (e.g. Firewall) Behaviour . . . . . . . . . . . .   6
     3.2.  Endpoint Behaviour  . . . . . . . . . . . . . . . . . . .   6
       3.2.1.  SYN . . . . . . . . . . . . . . . . . . . . . . . . .   8
       3.2.2.  SYN-ACK . . . . . . . . . . . . . . . . . . . . . . .  11
       3.2.3.  Pure ACK  . . . . . . . . . . . . . . . . . . . . . .  12
       3.2.4.  Window Probe  . . . . . . . . . . . . . . . . . . . .  13
       3.2.5.  FIN . . . . . . . . . . . . . . . . . . . . . . . . .  13
       3.2.6.  RST . . . . . . . . . . . . . . . . . . . . . . . . .  14
       3.2.7.  Retransmissions . . . . . . . . . . . . . . . . . . .  14
   4.  Rationale . . . . . . . . . . . . . . . . . . . . . . . . . .  15
     4.1.  The Reliability Argument  . . . . . . . . . . . . . . . .  15
     4.2.  SYNs  . . . . . . . . . . . . . . . . . . . . . . . . . .  16
       4.2.1.  Argument 1a: Unrecognized CE on the SYN . . . . . . .  16
       4.2.2.  Argument 1b: Unrecognized ECT on the SYN  . . . . . .  18
       4.2.3.  Argument 2: DoS Attacks . . . . . . . . . . . . . . .  20
     4.3.  SYN-ACKs  . . . . . . . . . . . . . . . . . . . . . . . .  20
     4.4.  Pure ACKs . . . . . . . . . . . . . . . . . . . . . . . .  22
       4.4.1.  Cwnd Response to CE-Marked Pure ACKs  . . . . . . . .  23
       4.4.2.  ACK Rate Response to CE-Marked Pure ACKs  . . . . . .  24
       4.4.3.  Summary: Enabling ECN on Pure ACKs  . . . . . . . . .  25
     4.5.  Window Probes . . . . . . . . . . . . . . . . . . . . . .  25
     4.6.  FINs  . . . . . . . . . . . . . . . . . . . . . . . . . .  26
     4.7.  RSTs  . . . . . . . . . . . . . . . . . . . . . . . . . .  26
     4.8.  Retransmitted Packets.  . . . . . . . . . . . . . . . . .  27
   5.  Interaction with popular variants or derivatives of TCP . . .  28
     5.1.  SCTP  . . . . . . . . . . . . . . . . . . . . . . . . . .  29
     5.2.  IW10  . . . . . . . . . . . . . . . . . . . . . . . . . .  29
     5.3.  TFO . . . . . . . . . . . . . . . . . . . . . . . . . . .  30
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  30
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