DualQ Coupled AQMs for Low Latency, Low Loss and Scalable Throughput (L4S)
draft-ietf-tsvwg-aqm-dualq-coupled-08

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Transport Area working group (tsvwg)                      K. De Schepper
Internet-Draft                                           Nokia Bell Labs
Intended status: Experimental                            B. Briscoe, Ed.
Expires: May 8, 2019                                           CableLabs
                                                           O. Bondarenko
                                                     Simula Research Lab
                                                                I. Tsang
                                                                   Nokia
                                                       November 04, 2018

  DualQ Coupled AQMs for Low Latency, Low Loss and Scalable Throughput
                                 (L4S)
                 draft-ietf-tsvwg-aqm-dualq-coupled-08

Abstract

   The Low Latency Low Loss Scalable Throughput (L4S) architecture
   allows data flows over the public Internet to predictably achieve
   ultra-low queuing latency, generally zero congestion loss and scaling
   of per-flow throughput without the problems of traditional TCP.  To
   achieve this, L4S data flows use a 'scalable' congestion control
   similar to Data Centre TCP (DCTCP) 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 starvation.  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.

   The Coupled AQM ensures that a flow runs at about the same rate
   whether it uses DCTCP or TCP Reno/Cubic.  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 eliminates network configuration.

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 May 8, 2019                  [Page 1]
Internet-Draft             DualQ Coupled AQMs              November 2018

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   This Internet-Draft will expire on May 8, 2019.

Copyright Notice

   Copyright (c) 2018 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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Problem and Scope . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
     1.3.  Features  . . . . . . . . . . . . . . . . . . . . . . . .   6
   2.  DualQ Coupled AQM . . . . . . . . . . . . . . . . . . . . . .   7
     2.1.  Coupled AQM . . . . . . . . . . . . . . . . . . . . . . .   8
     2.2.  Dual Queue  . . . . . . . . . . . . . . . . . . . . . . .   9
     2.3.  Traffic Classification  . . . . . . . . . . . . . . . . .   9
     2.4.  Overall DualQ Coupled AQM Structure . . . . . . . . . . .  10
     2.5.  Normative Requirements for a DualQ Coupled AQM  . . . . .  12
       2.5.1.  Functional Requirements . . . . . . . . . . . . . . .  12
         2.5.1.1.  Requirements in Unexpected Cases  . . . . . . . .  13
       2.5.2.  Management Requirements . . . . . . . . . . . . . . .  15
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16