Identifying Modified Explicit Congestion Notification (ECN) Semantics for Ultra-Low Queuing Delay (L4S)
draft-ietf-tsvwg-ecn-l4s-id-02
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Active Internet-Draft (tsvwg WG)
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2018-03-22
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draft-briscoe-tsvwg-ecn-l4s-id
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IETF
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(None)
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WG Document
(wg milestone:
Sep 2018 - Submit "Identifying ...
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Document shepherd |
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Wesley Eddy
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IESG |
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I-D Exists
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Consensus Boilerplate |
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Unknown
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(None)
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Send notices to |
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Wesley Eddy <wes@mti-systems.com>
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Transport Services (tsv) K. De Schepper
Internet-Draft Nokia Bell Labs
Intended status: Experimental B. Briscoe, Ed.
Expires: September 23, 2018 CableLabs
March 22, 2018
Identifying Modified Explicit Congestion Notification (ECN) Semantics
for Ultra-Low Queuing Delay (L4S)
draft-ietf-tsvwg-ecn-l4s-id-02
Abstract
This specification defines the identifier to be used on IP packets
for a new network service called low latency, low loss and scalable
throughput (L4S). It is similar to the original (or 'Classic')
Explicit Congestion Notification (ECN). 'Classic' ECN marking was
required to be equivalent to a drop, both when applied in the network
and when responded to by a transport. Unlike 'Classic' ECN marking,
for packets carrying the L4S identifier, the network applies marking
more immediately and more aggressively than drop, and the transport
response to each mark is reduced and smoothed relative to that for
drop. The two changes counterbalance each other so that the
throughput of an L4S flow will be roughly the same as a 'Classic'
flow under the same conditions. However, the much more frequent
control signals and the finer responses to them result in ultra-low
queuing delay without compromising link utilization, even during high
load. Examples of new active queue management (AQM) marking
algorithms and examples of new transports (whether TCP-like or real-
time) are specified separately. The new L4S identifier is the key
piece that enables them to interwork and distinguishes them from
'Classic' traffic. It gives an incremental migration path so that
existing 'Classic' TCP traffic will be no worse off, but it can be
prevented from degrading the ultra-low delay and loss of the new
scalable transports.
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
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
De Schepper & Briscoe Expires September 23, 2018 [Page 1]
Internet-Draft ECN Semantics for Low Queuing Delay March 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 September 23, 2018.
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
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. Problem . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.3. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2. L4S Packet Identifier . . . . . . . . . . . . . . . . . . . . 7
2.1. Consensus Choice of L4S Packet Identifier: Requirements . 7
2.2. L4S Packet Identification at Run-Time . . . . . . . . . . 8
2.3. Interaction of the L4S Identifier with other Identifiers 8
2.4. Pre-Requisite Transport Layer Behaviour . . . . . . . . . 9
2.4.1. Pre-Requisite Congestion Response . . . . . . . . . . 10
2.4.2. Pre-Requisite Transport Feedback . . . . . . . . . . 11
2.5. Exception for L4S Packet Identification by Network Nodes
with Transport-Layer Awareness . . . . . . . . . . . . . 11
2.6. The Meaning of L4S CE Relative to Drop . . . . . . . . . 12
3. L4S Experiments . . . . . . . . . . . . . . . . . . . . . . . 13
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
5. Security Considerations . . . . . . . . . . . . . . . . . . . 13
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 13
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