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Congestion Exposure (ConEx) Concepts, Abstract Mechanism and Requirements
draft-ietf-conex-abstract-mech-12

Document type: Active Internet-Draft (conex WG)
Document stream: IETF
Last updated: 2014-08-08 (latest revision 2014-07-21)
Intended RFC status: Informational
Other versions: plain text, xml, pdf, html

IETF State: Submitted to IESG for Publication
Consensus: Yes
Document shepherd: Marcelo Bagnulo
Shepherd Write-Up: Last changed 2014-03-26

IESG State: Waiting for Writeup
IANA Review State: IANA OK - No Actions Needed
IANA Action State: None
Responsible AD: Martin Stiemerling
Send notices to: conex-chairs@tools.ietf.org, draft-ietf-conex-abstract-mech@tools.ietf.org

Congestion Exposure (ConEx) Working                            M. Mathis
Group                                                        Google, Inc
Internet-Draft                                                B. Briscoe
Intended status: Informational                                        BT
Expires: January 22, 2015                                  July 21, 2014

      Congestion Exposure (ConEx) Concepts, Abstract Mechanism and
                              Requirements
                   draft-ietf-conex-abstract-mech-12

Abstract

   This document describes an abstract mechanism by which senders inform
   the network about the congestion encountered by packets earlier in
   the same flow.  Today, network elements at any layer may signal
   congestion to the receiver by dropping packets or by 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 "ConEx Concepts
   and Use Cases" provides the entry-point to the set of ConEx
   documentation.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on January 22, 2015.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the

Mathis & Briscoe        Expires January 22, 2015                [Page 1]
Internet-Draft    ConEx Concepts and Abstract Mechanism        July 2014

   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 . . . . . . . . . . . . . . . . . 11
     4.1.  Naive Encoding . . . . . . . . . . . . . . . . . . . . . . 11
     4.2.  Null Encoding  . . . . . . . . . . . . . . . . . . . . . . 12
     4.3.  ECN Based Encoding . . . . . . . . . . . . . . . . . . . . 12
     4.4.  Independent Bits . . . . . . . . . . . . . . . . . . . . . 13
     4.5.  Codepoint Encoding . . . . . . . . . . . . . . . . . . . . 13
     4.6.  Units Implied by an Encoding . . . . . . . . . . . . . . . 14
   5.  Congestion Exposure Components . . . . . . . . . . . . . . . . 15
     5.1.  Network Devices (Not modified) . . . . . . . . . . . . . . 15
     5.2.  Modified Senders . . . . . . . . . . . . . . . . . . . . . 15
     5.3.  Receivers (Optionally Modified)  . . . . . . . . . . . . . 15
     5.4.  Policy Devices . . . . . . . . . . . . . . . . . . . . . . 16
       5.4.1.  Congestion Monitoring Devices  . . . . . . . . . . . . 16
       5.4.2.  Rest-of-Path Congestion Monitoring . . . . . . . . . . 17
       5.4.3.  Congestion Policers  . . . . . . . . . . . . . . . . . 17
     5.5.  Audit  . . . . . . . . . . . . . . . . . . . . . . . . . . 18
   6.  Support for Incremental Deployment . . . . . . . . . . . . . . 21
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 24

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