Low Latency, Low Loss, Scalable Throughput (L4S) Internet Service: Architecture
draft-ietf-tsvwg-l4s-arch-08
Transport Area Working Group B. Briscoe, Ed.
Internet-Draft Independent
Intended status: Informational K. De Schepper
Expires: May 19, 2021 Nokia Bell Labs
M. Bagnulo Braun
Universidad Carlos III de Madrid
G. White
CableLabs
November 15, 2020
Low Latency, Low Loss, Scalable Throughput (L4S) Internet Service:
Architecture
draft-ietf-tsvwg-l4s-arch-08
Abstract
This document describes the L4S architecture, which enables Internet
applications to achieve Low queuing Latency, Low Loss, and Scalable
throughput (L4S). The insight on which L4S is based is that the root
cause of queuing delay is in the congestion controllers of senders,
not in the queue itself. The L4S architecture is intended to enable
_all_ Internet applications to transition away from congestion
control algorithms that cause queuing delay, to a new class of
congestion controls that induce very little queuing, aided by
explicit congestion signaling from the network. This new class of
congestion control can provide low latency for capacity-seeking
flows, so applications can achieve both high bandwidth and low
latency.
The architecture primarily concerns incremental deployment. It
defines mechanisms that allow the new class of L4S congestion
controls to coexist with 'Classic' congestion controls in a shared
network. These mechanisms aim to ensure that the latency and
throughput performance using an L4S-compliant congestion controller
is usually much better (and never worse) than the performance would
have been using a 'Classic' congestion controller, and that competing
flows continuing to use 'Classic' controllers are typically not
impacted by the presence of L4S. These characteristics are important
to encourage adoption of L4S congestion control algorithms and L4S
compliant network elements.
The L4S architecture consists of three components: network support to
isolate L4S traffic from classic traffic; protocol features that
allow network elements to identify L4S traffic; and host support for
L4S congestion controls.
Briscoe, et al. Expires May 19, 2021 [Page 1]
Internet-Draft L4S Architecture November 2020
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. L4S Architecture Overview . . . . . . . . . . . . . . . . . . 5
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. L4S Architecture Components . . . . . . . . . . . . . . . . . 7
5. Rationale . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.1. Why These Primary Components? . . . . . . . . . . . . . . 12
5.2. What L4S adds to Existing Approaches . . . . . . . . . . 14
6. Applicability . . . . . . . . . . . . . . . . . . . . . . . . 17
6.1. Applications . . . . . . . . . . . . . . . . . . . . . . 17
6.2. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . 19
6.3. Applicability with Specific Link Technologies . . . . . . 20
6.4. Deployment Considerations . . . . . . . . . . . . . . . . 20
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