Interactions between Low Latency, Low Loss, Scalable Throughput (L4S) and Differentiated Services
draft-briscoe-tsvwg-l4s-diffserv-02

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Transport Area Working Group                                  B. Briscoe
Internet-Draft                                                 CableLabs
Intended status: Informational                          November 1, 2018
Expires: May 5, 2019

 Interactions between Low Latency, Low Loss, Scalable Throughput (L4S)
                      and Differentiated Services
                  draft-briscoe-tsvwg-l4s-diffserv-02

Abstract

   L4S and Diffserv offer somewhat overlapping services (low latency and
   low loss), but bandwidth allocation is out of scope for L4S.
   Therefore there is scope for the two approaches to complement each
   other, but also to conflict.  This informational document explains
   how the two approaches interact, how they can be arranged to
   complement each other and in which cases one can stand alone without
   needing the other.

Status of This Memo

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   This Internet-Draft will expire on May 5, 2019.

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   Copyright (c) 2018 IETF Trust and the persons identified as the
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Briscoe                    Expires May 5, 2019                  [Page 1]
Internet-Draft    Interactions between L4S and Diffserv    November 2018

   include Simplified BSD License text as described in Section 4.e of
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Document Roadmap  . . . . . . . . . . . . . . . . . . . .   4
   2.  Architectural Comparison of L4S and Diffserv  . . . . . . . .   4
     2.1.  Overlaps between L4S and Diffserv . . . . . . . . . . . .   4
     2.2.  Differences between L4S and Diffserv  . . . . . . . . . .   4
   3.  Low Latency Diffserv Classes within a DualQ Bandwidth Pool  .   5
   4.  DualQ Bandwidth Pool within a Hierarchy of (Diffserv)
       Bandwidth Queues  . . . . . . . . . . . . . . . . . . . . . .   9
     4.1.  DualQ Complemented by an Assured Bandwidth Service  . . .  10
     4.2.  DualQ Complemented by a Guaranteed Low Latency Service  .  12
     4.3.  DualQ Complemented by a Scavenger Service . . . . . . . .  13
   5.  Coupling More than Two AQMs within a Bandwidth Pool . . . . .  14
   6.  Applicability of Coupled AQM to Global Diffserv PHBs  . . . .  14
   7.  Best Practice for Classification and Marking  . . . . . . . .  16
     7.1.  Never Re-Mark a DSCP  . . . . . . . . . . . . . . . . . .  16
     7.2.  Classification Order  . . . . . . . . . . . . . . . . . .  16
       7.2.1.  Classification Order: Problem . . . . . . . . . . . .  17
       7.2.2.  Classification Order: Solutions . . . . . . . . . . .  17
   8.  Policing and Traffic Conditioning . . . . . . . . . . . . . .  17
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  18
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  18
   11. Comments Solicited  . . . . . . . . . . . . . . . . . . . . .  18
   12. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  18
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  18
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  18
     13.2.  Informative References . . . . . . . . . . . . . . . . .  18
   Appendix A.  Open Issues  . . . . . . . . . . . . . . . . . . . .  20
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  20

1.  Introduction

   The Low Latency Low Loss Scalable throughput (L4S) Internet service
   [I-D.ietf-tsvwg-l4s-arch] provides a new Internet service that could
   eventually replace best efforts, but with ultra-low queuing delay and
   loss.  A structure called the Dual-Queue Coupled AQM manages to
   provide the L4S service alongside a second queue for Classic Internet
   traffic, but without prejudging the bandwidth allocations between
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