DualQ Coupled AQMs for Low Latency, Low Loss and Scalable Throughput (L4S)
draft-ietf-tsvwg-aqm-dualq-coupled-10
Transport Area working group (tsvwg) K. De Schepper
Internet-Draft Nokia Bell Labs
Intended status: Experimental B. Briscoe, Ed.
Expires: January 9, 2020 G. White
CableLabs
July 8, 2019
DualQ Coupled AQMs for Low Latency, Low Loss and Scalable Throughput
(L4S)
draft-ietf-tsvwg-aqm-dualq-coupled-10
Abstract
The Low Latency Low Loss Scalable Throughput (L4S) architecture
allows data flows over the public Internet to achieve consistent
ultra-low queuing latency, generally zero congestion loss and scaling
of per-flow throughput without the scaling problems of traditional
TCP. To achieve this, L4S data flows have to use one of the family
of 'Scalable' congestion controls (Data Centre TCP and TCP Prague are
examples) 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 a small capacity share. 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.
Analytical study and implementation testing of the Coupled AQM have
shown that Scalable and Classic flows competing under similar
conditions run at roughly the same rate. 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 requires no configuration for the public Internet.
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 January 9, 2020 [Page 1]
Internet-Draft DualQ Coupled AQMs July 2019
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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 9, 2020.
Copyright Notice
Copyright (c) 2019 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
Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Outline of the Problem . . . . . . . . . . . . . . . . . 3
1.2. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Terminology . . . . . . . . . . . . . . . . . . . . . . . 7
1.4. Features . . . . . . . . . . . . . . . . . . . . . . . . 8
2. DualQ Coupled AQM . . . . . . . . . . . . . . . . . . . . . . 9
2.1. Coupled AQM . . . . . . . . . . . . . . . . . . . . . . . 9
2.2. Dual Queue . . . . . . . . . . . . . . . . . . . . . . . 10
2.3. Traffic Classification . . . . . . . . . . . . . . . . . 11
2.4. Overall DualQ Coupled AQM Structure . . . . . . . . . . . 11
2.5. Normative Requirements for a DualQ Coupled AQM . . . . . 14
2.5.1. Functional Requirements . . . . . . . . . . . . . . . 14
2.5.1.1. Requirements in Unexpected Cases . . . . . . . . 15
2.5.2. Management Requirements . . . . . . . . . . . . . . . 16
2.5.2.1. Configuration . . . . . . . . . . . . . . . . . . 16
Show full document text