Low Latency, Low Loss, Scalable Throughput (L4S) Internet Service: Architecture
draft-ietf-tsvwg-l4s-arch-03

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Transport Area Working Group                             B. Briscoe, Ed.
Internet-Draft                                                 CableLabs
Intended status: Informational                            K. De Schepper
Expires: April 25, 2019                                  Nokia Bell Labs
                                                        M. Bagnulo Braun
                                        Universidad Carlos III de Madrid
                                                        October 22, 2018

   Low Latency, Low Loss, Scalable Throughput (L4S) Internet Service:
                              Architecture
                      draft-ietf-tsvwg-l4s-arch-03

Abstract

   This document describes the L4S architecture for the provision of a
   new Internet service that could eventually replace best efforts for
   all traffic: Low Latency, Low Loss, Scalable throughput (L4S).  It is
   becoming common for _all_ (or most) applications being run by a user
   at any one time to require low latency.  However, the only solution
   the IETF can offer for ultra-low queuing delay is Diffserv, which
   only favours a minority of packets at the expense of others.  In
   extensive testing the new L4S service keeps average queuing delay
   under a millisecond for _all_ applications even under very heavy
   load, without sacrificing utilization; and it keeps congestion loss
   to zero.  It is becoming widely recognized that adding more access
   capacity gives diminishing returns, because latency is becoming the
   critical problem.  Even with a high capacity broadband access, the
   reduced latency of L4S remarkably and consistently improves
   performance under load for applications such as interactive video,
   conversational video, voice, Web, gaming, instant messaging, remote
   desktop and cloud-based apps (even when all being used at once over
   the same access link).  The insight is that the root cause of queuing
   delay is in TCP, not in the queue.  By fixing the sending TCP (and
   other transports) queuing latency becomes so much better than today
   that operators will want to deploy the network part of L4S to enable
   new products and services.  Further, the network part is simple to
   deploy - incrementally with zero-config.  Both parts, sender and
   network, ensure coexistence with other legacy traffic.  At the same
   time L4S solves the long-recognized problem with the future
   scalability of TCP throughput.

   This document describes the L4S architecture, briefly describing the
   different components and how the work together to provide the
   aforementioned enhanced Internet service.

Briscoe, et al.          Expires April 25, 2019                 [Page 1]
Internet-Draft              L4S Architecture                October 2018

Status of This Memo

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

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   This Internet-Draft will expire on April 25, 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
   2.  L4S Architecture Overview . . . . . . . . . . . . . . . . . .   4
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   6
   4.  L4S Architecture Components . . . . . . . . . . . . . . . . .   7
   5.  Rationale . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Why These Primary Components? . . . . . . . . . . . . . .   9
     5.2.  Why Not Alternative Approaches? . . . . . . . . . . . . .  10
   6.  Applicability . . . . . . . . . . . . . . . . . . . . . . . .  13
     6.1.  Applications  . . . . . . . . . . . . . . . . . . . . . .  13
     6.2.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . .  14
     6.3.  Deployment Considerations . . . . . . . . . . . . . . . .  15