DualQ Coupled AQMs for Low Latency, Low Loss and Scalable Throughput (L4S)
draft-ietf-tsvwg-aqm-dualq-coupled-06

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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 19, 2019                                      CableLabs
                                                           O. Bondarenko
                                                     Simula Research Lab
                                                                I. Tsang
                                                                   Nokia
                                                           July 18, 2018

  DualQ Coupled AQMs for Low Latency, Low Loss and Scalable Throughput
                                 (L4S)
                 draft-ietf-tsvwg-aqm-dualq-coupled-06

Abstract

   Data Centre TCP (DCTCP) was designed to provide predictably low
   queuing latency, near-zero loss, and throughput scalability using
   explicit congestion notification (ECN) and an extremely simple
   marking behaviour on switches.  However, DCTCP does not co-exist with
   existing TCP traffic---DCTCP is so aggressive that existing TCP
   algorithms approach starvation.  So, until now, DCTCP could only be
   deployed where a clean-slate environment could be arranged, such as
   in private data centres.  This specification defines `DualQ Coupled
   Active Queue Management (AQM)' to allow scalable congestion controls
   like DCTCP 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, but without inspecting transport
   layer flow identifiers.  When tested in a residential broadband
   setting, DCTCP achieved 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.

   Internet-Drafts are working documents of the Internet Engineering
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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any

De Schepper, et al.     Expires January 19, 2019                [Page 1]
Internet-Draft             DualQ Coupled AQMs                  July 2018

   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 19, 2019.

Copyright Notice

   Copyright (c) 2018 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.  Problem and Scope . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   5
     1.3.  Features  . . . . . . . . . . . . . . . . . . . . . . . .   6
   2.  DualQ Coupled AQM . . . . . . . . . . . . . . . . . . . . . .   7
     2.1.  Coupled AQM . . . . . . . . . . . . . . . . . . . . . . .   7
     2.2.  Dual Queue  . . . . . . . . . . . . . . . . . . . . . . .   8
     2.3.  Traffic Classification  . . . . . . . . . . . . . . . . .   8
     2.4.  Overall DualQ Coupled AQM Structure . . . . . . . . . . .   9
     2.5.  Normative Requirements for a DualQ Coupled AQM  . . . . .  11
       2.5.1.  Functional Requirements . . . . . . . . . . . . . . .  11
         2.5.1.1.  Requirements in Unexpected Cases  . . . . . . . .  12
       2.5.2.  Management Requirements . . . . . . . . . . . . . . .  13
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  14
     4.1.  Overload Handling . . . . . . . . . . . . . . . . . . . .  14
       4.1.1.  Avoiding Classic Starvation: Sacrifice L4S Throughput
               or Delay? . . . . . . . . . . . . . . . . . . . . . .  15
       4.1.2.  Congestion Signal Saturation: Introduce L4S Drop or