Congestion Exposure (ConEx) Concepts, Abstract Mechanism, and Requirements
RFC 7713
Document | Type | RFC - Informational (December 2015; No errata) | |
---|---|---|---|
Authors | Matt Mathis , Bob Briscoe | ||
Last updated | 2015-12-28 | ||
Stream | Internent Engineering Task Force (IETF) | ||
Formats | plain text html pdf htmlized (tools) htmlized bibtex | ||
Reviews | |||
Stream | WG state | Submitted to IESG for Publication | |
Document shepherd | Marcelo Bagnulo | ||
Shepherd write-up | Show (last changed 2014-03-26) | ||
IESG | IESG state | RFC 7713 (Informational) | |
Action Holders |
(None)
|
||
Consensus Boilerplate | Yes | ||
Telechat date | |||
Responsible AD | Martin Stiemerling | ||
Send notices to | (None) | ||
IANA | IANA review state | IANA OK - No Actions Needed | |
IANA action state | No IANA Actions |
Internet Engineering Task Force (IETF) M. Mathis Request for Comments: 7713 Google, Inc. Category: Informational B. Briscoe ISSN: 2070-1721 BT December 2015 Congestion Exposure (ConEx) Concepts, Abstract Mechanism, and Requirements Abstract This document describes an abstract mechanism by which senders inform the network about the congestion recently encountered by packets in the same flow. Today, network elements at any layer may signal congestion to the receiver by dropping packets or by Explicit Congestion Notification (ECN) markings, and the receiver passes this information back to the sender in transport-layer feedback. The mechanism described here enables the sender to also relay this congestion information back into the network in-band at the IP layer, such that the total amount of congestion from all elements on the path is revealed to all IP elements along the path, where it could, for example, be used to provide input to traffic management. This mechanism is called Congestion Exposure, or ConEx. The companion document, "Congestion Exposure (ConEx) Concepts and Use Cases" (RFC 6789), provides the entry point to the set of ConEx documentation. 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/rfc7713. Mathis & Briscoe Informational [Page 1] RFC 7713 ConEx Concepts and Abstract Mechanism December 2015 Copyright Notice 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 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 2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6 3. Requirements for the ConEx Abstract Mechanism . . . . . . . . 7 3.1. Requirements for ConEx Signals . . . . . . . . . . . . . 7 3.2. Constraints on the Audit Function . . . . . . . . . . . . 8 3.3. Requirements for Non-abstract ConEx Specifications . . . 9 4. Encoding Congestion Exposure . . . . . . . . . . . . . . . . 12 4.1. Naive Encoding . . . . . . . . . . . . . . . . . . . . . 12 4.2. Null Encoding . . . . . . . . . . . . . . . . . . . . . . 13 4.3. ECN-Based Encoding . . . . . . . . . . . . . . . . . . . 13 4.4. Independent Bits . . . . . . . . . . . . . . . . . . . . 14 4.5. Codepoint Encoding . . . . . . . . . . . . . . . . . . . 14 4.6. Units Implied by an Encoding . . . . . . . . . . . . . . 15 5. Congestion Exposure Components . . . . . . . . . . . . . . . 16 5.1. Network Devices (Not Modified) . . . . . . . . . . . . . 16 5.2. Modified Senders . . . . . . . . . . . . . . . . . . . . 16 5.3. Receivers (Optionally Modified) . . . . . . . . . . . . . 17 5.4. Policy Devices . . . . . . . . . . . . . . . . . . . . . 17 5.4.1. Congestion Monitoring Devices . . . . . . . . . . . . 18 5.4.2. Rest-of-Path Congestion Monitoring . . . . . . . . . 18 5.4.3. Congestion Policers . . . . . . . . . . . . . . . . . 18 5.5. Audit . . . . . . . . . . . . . . . . . . . . . . . . . . 19 6. Support for Incremental Deployment . . . . . . . . . . . . . 23 7. Security Considerations . . . . . . . . . . . . . . . . . . . 25 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 27 8.1. Normative References . . . . . . . . . . . . . . . . . . 27Show full document text