The Benefits of using Explicit Congestion Notification (ECN)
draft-ietf-aqm-ecn-benefits-04

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Network Working Group                                       G. Fairhurst
Internet-Draft                                    University of Aberdeen
Intended status: Informational                                  M. Welzl
Expires: November 6, 2015                             University of Oslo
                                                            May 05, 2015

      The Benefits of using Explicit Congestion Notification (ECN)
                     draft-ietf-aqm-ecn-benefits-04

Abstract

   The goal of this document is to describe the potential benefits when
   applications use a transport that enables Explicit Congestion
   Notification (ECN).  The document outlines the principal gains in
   terms of increased throughput, reduced delay and other benefits when
   ECN is used over network paths that include equipment that supports
   ECN-marking.  It also describes methods that can help successful
   deployment of ECN.  It does not propose new algorithms to use ECN,
   nor does it describe the details of implementation of ECN in endpoint
   devices (Internet hosts), routers or other network devices.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on November 6, 2015.

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   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents

Fairhurst & Welzl       Expires November 6, 2015                [Page 1]
Internet-Draft               Benefits of ECN                    May 2015

   carefully, as they describe your rights and restrictions with respect
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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Benefit of using ECN to avoid Congestion Loss . . . . . . . .   4
     2.1.  Improved Throughput . . . . . . . . . . . . . . . . . . .   4
     2.2.  Reduced Head-of-Line Blocking . . . . . . . . . . . . . .   5
     2.3.  Reduced Probability of RTO Expiry . . . . . . . . . . . .   5
     2.4.  Applications that do not Retransmit Lost Packets  . . . .   6
     2.5.  Making Incipient Congestion Visible . . . . . . . . . . .   6
     2.6.  Opportunities for new Transport Mechanisms  . . . . . . .   7
       2.6.1.  Benefits from other forms of ECN-Marking/Reactions  .   7
   3.  Network Support for ECN . . . . . . . . . . . . . . . . . . .   8
     3.1.  Enabling ECN in Network Devices . . . . . . . . . . . . .   9
     3.2.  Tunneling ECN and the use of ECN by Lower Layer Networks    9
     3.3.  Bleaching and Middlebox Requirements to deploy ECN  . . .   9
     3.4.  Impact on non-ECN flows . . . . . . . . . . . . . . . . .  10
   4.  Using ECN across the Internet . . . . . . . . . . . . . . . .  10
     4.1.  Partial Deployment  . . . . . . . . . . . . . . . . . . .  11
     4.2.  Verifying whether a Path Really Supports ECN  . . . . . .  11
     4.3.  Detecting ECN Receiver Feedback Cheating  . . . . . . . .  11
   5.  Summary: Enabling ECN in Network Devices and Hosts  . . . . .  12
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  13
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   9.  Revision Information  . . . . . . . . . . . . . . . . . . . .  13
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  15
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  15
     10.2.  Informative References . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   Internet Transports (such as TCP and SCTP) are implemented in
   endpoints (Internet hosts) and have two ways to detect network
   congestion: the loss of an IP packet or, if Explicit Congestion
   Notification (ECN) [RFC3168] is enabled, the reception of a packet
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