A PIE-Based AQM for DOCSIS Cable Modems
draft-ietf-aqm-docsis-pie-01

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Document Type Active Internet-Draft (aqm WG)
Last updated 2016-02-10 (latest revision 2015-09-29)
Replaces draft-white-aqm-docsis-pie
Stream IETF
Intended RFC status Informational
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Document shepherd Wesley Eddy
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Send notices to "Wesley Eddy" <wes@mti-systems.com>
Active Queue Management and Packet Scheduling (aqm)             G. White
Internet-Draft                                                 CableLabs
Intended status: Informational                                    R. Pan
Expires: April 1, 2016                                     Cisco Systems
                                                      September 29, 2015

                A PIE-Based AQM for DOCSIS Cable Modems
                      draft-ietf-aqm-docsis-pie-01

Abstract

   Cable modems based on the DOCSIS(R) specification provide broadband
   Internet access to over one hundred million users worldwide.  In some
   cases, the cable modem connection is the bottleneck (lowest speed)
   link between the customer and the Internet.  As a result, the impact
   of buffering and bufferbloat in the cable modem can have a
   significant effect on user experience.  The CableLabs DOCSIS 3.1
   specification introduces requirements for cable modems to support an
   Active Queue Management (AQM) algorithm that is intended to alleviate
   the impact that buffering has on latency sensitive traffic, while
   preserving bulk throughput performance.  In addition, the CableLabs
   DOCSIS 3.0 specifications have also been amended to contain similar
   requirements.  This document describes the requirements on Active
   Queue Management that apply to DOCSIS equipment, including a
   description of the "DOCSIS-PIE" algorithm that is required on DOCSIS
   3.1 cable modems.

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
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   Drafts is at http://datatracker.ietf.org/drafts/current/.

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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 1, 2016.

White & Pan               Expires April 1, 2016                 [Page 1]
Internet-Draft                 docsis-pie                 September 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
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   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.  Overview of DOCSIS AQM Requirements . . . . . . . . . . . . .   3
   3.  The DOCSIS MAC Layer and Service Flows  . . . . . . . . . . .   3
   4.  DOCSIS-PIE vs. PIE  . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Latency Target  . . . . . . . . . . . . . . . . . . . . .   5
     4.2.  Departure rate estimation . . . . . . . . . . . . . . . .   5
     4.3.  Enhanced burst protection . . . . . . . . . . . . . . . .   6
     4.4.  Expanded auto-tuning range  . . . . . . . . . . . . . . .   7
     4.5.  Trigger for exponential decay . . . . . . . . . . . . . .   7
     4.6.  Drop probability scaling  . . . . . . . . . . . . . . . .   7
     4.7.  Support for explicit congestion notification  . . . . . .   8
   5.  Implementation Guidance . . . . . . . . . . . . . . . . . . .   8
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
   Appendix A.  DOCSIS-PIE Algorithm definition  . . . . . . . . . .   9
     A.1.  DOCSIS-PIE AQM Constants and Variables  . . . . . . . . .   9
       A.1.1.  Configuration parameters  . . . . . . . . . . . . . .  10
       A.1.2.  Constant values . . . . . . . . . . . . . . . . . . .  10
       A.1.3.  Variables . . . . . . . . . . . . . . . . . . . . . .  10
       A.1.4.  Public/system functions:  . . . . . . . . . . . . . .  11
     A.2.  DOCSIS-PIE AQM Control Path . . . . . . . . . . . . . . .  11
     A.3.  DOCSIS-PIE AQM Data Path  . . . . . . . . . . . . . . . .  13
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   A recent resurgence of interest in Active Queue Management, arising
   from a recognition of the inadequacies of drop tail queuing in the
   presence of loss-based congestion control algorithms, has resulted in
   the development of new algorithms that appear to provide very good
   congestion feedback to current TCP algorithms, while also having
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