DualQ Coupled AQMs for Low Latency, Low Loss and Scalable Throughput (L4S)
draft-ietf-tsvwg-aqm-dualq-coupled-10

Document Type Active Internet-Draft (tsvwg WG)
Last updated 2019-07-08
Replaces draft-briscoe-tsvwg-aqm-dualq-coupled
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Transport Area working group (tsvwg)                      K. De Schepper
Internet-Draft                                           Nokia Bell Labs
Intended status: Experimental                            B. Briscoe, Ed.
Expires: January 9, 2020                                        G. White
                                                               CableLabs
                                                            July 8, 2019

  DualQ Coupled AQMs for Low Latency, Low Loss and Scalable Throughput
                                 (L4S)
                 draft-ietf-tsvwg-aqm-dualq-coupled-10

Abstract

   The Low Latency Low Loss Scalable Throughput (L4S) architecture
   allows data flows over the public Internet to achieve consistent
   ultra-low queuing latency, generally zero congestion loss and scaling
   of per-flow throughput without the scaling problems of traditional
   TCP.  To achieve this, L4S data flows have to use one of the family
   of 'Scalable' congestion controls (Data Centre TCP and TCP Prague are
   examples) and a form of Explicit Congestion Notification (ECN) with
   modified behaviour.  However, until now, Scalable congestion controls
   did not co-exist with existing TCP Reno/Cubic traffic --- Scalable
   controls are so aggressive that 'Classic' TCP algorithms drive
   themselves to a small capacity share.  Therefore, until now, L4S
   controls could only be deployed where a clean-slate environment could
   be arranged, such as in private data centres (hence the name DCTCP).
   This specification defines `DualQ Coupled Active Queue Management
   (AQM)', which enables these Scalable congestion controls to safely
   co-exist with Classic Internet traffic.

   Analytical study and implementation testing of the Coupled AQM have
   shown that Scalable and Classic flows competing under similar
   conditions run at roughly the same rate.  It achieves this
   indirectly, without having to inspect transport layer flow
   identifiers.  When tested in a residential broadband setting, DCTCP
   also achieves sub-millisecond average queuing delay and zero
   congestion loss under a wide range of mixes of DCTCP and `Classic'
   broadband Internet traffic, without compromising the performance of
   the Classic traffic.  The solution also reduces network complexity
   and requires no configuration for the public Internet.

Status of This Memo

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

De Schepper, et al.      Expires January 9, 2020                [Page 1]
Internet-Draft             DualQ Coupled AQMs                  July 2019

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Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Outline of the Problem  . . . . . . . . . . . . . . . . .   3
     1.2.  Scope . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     1.3.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   7
     1.4.  Features  . . . . . . . . . . . . . . . . . . . . . . . .   8
   2.  DualQ Coupled AQM . . . . . . . . . . . . . . . . . . . . . .   9
     2.1.  Coupled AQM . . . . . . . . . . . . . . . . . . . . . . .   9
     2.2.  Dual Queue  . . . . . . . . . . . . . . . . . . . . . . .  10
     2.3.  Traffic Classification  . . . . . . . . . . . . . . . . .  11
     2.4.  Overall DualQ Coupled AQM Structure . . . . . . . . . . .  11
     2.5.  Normative Requirements for a DualQ Coupled AQM  . . . . .  14
       2.5.1.  Functional Requirements . . . . . . . . . . . . . . .  14
         2.5.1.1.  Requirements in Unexpected Cases  . . . . . . . .  15
       2.5.2.  Management Requirements . . . . . . . . . . . . . . .  16
         2.5.2.1.  Configuration . . . . . . . . . . . . . . . . . .  16
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