Identifying Modified Explicit Congestion Notification (ECN) Semantics for Ultra-Low Queuing Delay
draft-ietf-tsvwg-ecn-l4s-id-01

Document Type Active Internet-Draft (tsvwg WG)
Last updated 2017-10-30
Replaces draft-briscoe-tsvwg-ecn-l4s-id
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Document shepherd Wesley Eddy
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Transport Services (tsv)                                  K. De Schepper
Internet-Draft                                           Nokia Bell Labs
Intended status: Experimental                            B. Briscoe, Ed.
Expires: May 3, 2018                                           CableLabs
                                                        October 30, 2017

 Identifying Modified Explicit Congestion Notification (ECN) Semantics
                      for Ultra-Low Queuing Delay
                     draft-ietf-tsvwg-ecn-l4s-id-01

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
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De Schepper & Briscoe      Expires May 3, 2018                  [Page 1]
Internet-Draft     ECN Semantics for Low Queuing Delay      October 2017

   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 May 3, 2018.

Copyright Notice

   Copyright (c) 2017 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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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.  Pre-Requisite Transport Layer Behaviour . . . . . . . . .   8
       2.3.1.  Pre-Requisite Congestion Response . . . . . . . . . .   8
       2.3.2.  Pre-Requisite Transport Feedback  . . . . . . . . . .   9
     2.4.  Exception for L4S Packet Identification by Network Nodes
           with Transport-Layer Awareness  . . . . . . . . . . . . .  10
     2.5.  The Meaning of L4S CE Relative to Drop  . . . . . . . . .  11
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  11
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  12
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  12
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     6.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     6.2.  Informative References  . . . . . . . . . . . . . . . . .  13
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