Congestion Exposure (ConEx) Concepts and Use Cases
RFC 6789
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RFC - Informational
(December 2012; No errata)
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2015-10-14
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IETF
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RFC 6789 (Informational)
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Wesley Eddy
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Nandita Dukkipati (nanditad@google.com) is the document shepherd.
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Internet Engineering Task Force (IETF) B. Briscoe, Ed.
Request for Comments: 6789 BT
Category: Informational R. Woundy, Ed.
ISSN: 2070-1721 Comcast
A. Cooper, Ed.
CDT
December 2012
Congestion Exposure (ConEx) Concepts and Use Cases
Abstract
This document provides the entry point to the set of documentation
about the Congestion Exposure (ConEx) protocol. It explains the
motivation for including a ConEx marking at the IP layer: to expose
information about congestion to network nodes. Although such
information may have a number of uses, this document focuses on how
the information communicated by the ConEx marking can serve as the
basis for significantly more efficient and effective traffic
management than what exists on the Internet today.
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 5741.
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/rfc6789.
Briscoe, et al. Informational [Page 1]
RFC 6789 ConEx Concepts and Use Cases December 2012
Copyright Notice
Copyright (c) 2012 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 . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Concepts . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Congestion . . . . . . . . . . . . . . . . . . . . . . . . 5
2.2. Congestion-Volume . . . . . . . . . . . . . . . . . . . . 5
2.3. Rest-of-Path Congestion . . . . . . . . . . . . . . . . . 6
2.4. Definitions . . . . . . . . . . . . . . . . . . . . . . . 6
3. Core Use Case: Informing Traffic Management . . . . . . . . . 7
3.1. Use Case Description . . . . . . . . . . . . . . . . . . . 7
3.2. Additional Benefits . . . . . . . . . . . . . . . . . . . 9
3.3. Comparison with Existing Approaches . . . . . . . . . . . 9
4. Other Use Cases . . . . . . . . . . . . . . . . . . . . . . . 11
5. Deployment Arrangements . . . . . . . . . . . . . . . . . . . 12
6. Experimental Considerations . . . . . . . . . . . . . . . . . 13
7. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14
9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 15
10. Informative References . . . . . . . . . . . . . . . . . . . . 15
1. Introduction
The power of Internet technology comes from multiplexing shared
capacity with packets rather than circuits. Network operators aim to
provide sufficient shared capacity, but when too much packet load
meets too little shared capacity, congestion results. Congestion
appears as either increased delay, dropped packets, or packets
explicitly marked with Explicit Congestion Notification (ECN)
markings [RFC3168]. As described in Figure 1, congestion control
currently relies on the transport receiver detecting these
'Congestion Signals' and informing the transport sender in
'Congestion Feedback Signals'. The sender is then expected to reduce
its rate in response.
Briscoe, et al. Informational [Page 2]
RFC 6789 ConEx Concepts and Use Cases December 2012
This document provides the entry point to the set of documentation
about the Congestion Exposure (ConEx) protocol. It focuses on the
motivation for including a ConEx marking at the IP layer. (A
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