The Benefits of Using Explicit Congestion Notification (ECN)
RFC 8087
| Document | Type | RFC - Informational (March 2017; No errata) | |
|---|---|---|---|
| Authors | Gorry Fairhurst , Michael Welzl | ||
| Last updated | 2017-03-07 | ||
| Replaces | draft-welzl-ecn-benefits | ||
| Stream | IETF | ||
| Formats | plain text html pdf htmlized bibtex | ||
| Reviews | |||
| Stream | WG state | Submitted to IESG for Publication | |
| Document shepherd | Richard Scheffenegger | ||
| Shepherd write-up | Show (last changed 2015-08-10) | ||
| IESG | IESG state | RFC 8087 (Informational) | |
| Action Holders |
(None)
|
||
| Consensus Boilerplate | Yes | ||
| Telechat date | |||
| Responsible AD | Martin Stiemerling | ||
| Send notices to | (None) | ||
| IANA | IANA review state | Version Changed - Review Needed | |
| IANA action state | No IANA Actions | ||
Internet Engineering Task Force (IETF) G. Fairhurst
Request for Comments: 8087 University of Aberdeen
Category: Informational M. Welzl
ISSN: 2070-1721 University of Oslo
March 2017
The Benefits of Using Explicit Congestion Notification (ECN)
Abstract
The goal of this document is to describe the potential benefits of
applications using 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 a network path that includes equipment that supports
Congestion Experienced (CE) marking. It also discusses challenges
for 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
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc8087.
Fairhurst & Welzl Informational [Page 1]
RFC 8087 Benefits of ECN March 2017
Copyright Notice
Copyright (c) 2017 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
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Benefit of Using ECN to Avoid Congestion Loss . . . . . . . . 5
2.1. Improved Throughput . . . . . . . . . . . . . . . . . . . 5
2.2. Reduced Head-of-Line Blocking . . . . . . . . . . . . . . 6
2.3. Reduced Probability of RTO Expiry . . . . . . . . . . . . 6
2.4. Applications That Do Not Retransmit Lost Packets . . . . 7
2.5. Making Incipient Congestion Visible . . . . . . . . . . . 8
2.6. Opportunities for New Transport Mechanisms . . . . . . . 8
3. Network Support for ECN . . . . . . . . . . . . . . . . . . . 9
3.1. The ECN Field . . . . . . . . . . . . . . . . . . . . . . 10
3.2. Forwarding ECN-Capable IP Packets . . . . . . . . . . . . 10
3.3. Enabling ECN in Network Devices . . . . . . . . . . . . . 11
3.4. Coexistence of ECN and Non-ECN Flows . . . . . . . . . . 11
3.5. Bleaching and Middlebox Requirements to Deploy ECN . . . 11
3.6. Tunneling ECN and the Use of ECN by Lower-Layer Networks 12
4. Using ECN across the Internet . . . . . . . . . . . . . . . . 12
4.1. Partial Deployment . . . . . . . . . . . . . . . . . . . 13
4.2. Detecting Whether a Path Really Supports ECN . . . . . . 13
4.3. Detecting ECN-Receiver Feedback Cheating . . . . . . . . 14
5. Summary: Enabling ECN in Network Devices and Hosts . . . . . 14
6. Security Considerations . . . . . . . . . . . . . . . . . . . 15
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.1. Normative References . . . . . . . . . . . . . . . . . . 16
7.2. Informative References . . . . . . . . . . . . . . . . . 16
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
Fairhurst & Welzl Informational [Page 2]
RFC 8087 Benefits of ECN March 2017
1. Introduction
Internet transports (such as TCP and Stream Control Transmission
Protocol (SCTP)) are implemented in endpoints (Internet hosts) and
are designed to detect and react to network congestion. Congestion
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