TCP Alternative Backoff with ECN (ABE)
draft-ietf-tcpm-alternativebackoff-ecn-09

Document Type Active Internet-Draft (tcpm WG)
Last updated 2018-08-16 (latest revision 2018-08-14)
Replaces draft-khademi-tcpm-alternativebackoff-ecn
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Network Working Group                                         N. Khademi
Internet-Draft                                                  M. Welzl
Intended status: Experimental                         University of Oslo
Expires: February 15, 2019                                   G. Armitage
                                                                 Netflix
                                                            G. Fairhurst
                                                  University of Aberdeen
                                                         August 14, 2018

                 TCP Alternative Backoff with ECN (ABE)
               draft-ietf-tcpm-alternativebackoff-ecn-09

Abstract

   Active Queue Management (AQM) mechanisms allow for burst tolerance
   while enforcing short queues to minimise the time that packets spend
   enqueued at a bottleneck.  This can cause noticeable performance
   degradation for TCP connections traversing such a bottleneck,
   especially if there are only a few flows or their bandwidth-delay-
   product is large.  The reception of a Congestion Experienced (CE) ECN
   mark indicates that an AQM mechanism is used at the bottleneck, and
   therefore the bottleneck network queue is likely to be short.
   Feedback of this signal allows the TCP sender-side ECN reaction in
   congestion avoidance to reduce the Congestion Window (cwnd) by a
   smaller amount than the congestion control algorithm's reaction to
   inferred packet loss.  This specification therefore defines an
   experimental change to the TCP reaction specified in RFC3168, as
   permitted by RFC 8311.

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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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on February 15, 2019.

Khademi, et al.         Expires February 15, 2019               [Page 1]
Internet-Draft                     ABE                       August 2018

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definitions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Specification . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Choice of ABE Multiplier  . . . . . . . . . . . . . . . .   4
   4.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Why Use ECN to Vary the Degree of Backoff?  . . . . . . .   6
     4.2.  An RTT-based response to indicated congestion . . . . . .   7
   5.  ABE Deployment Requirements . . . . . . . . . . . . . . . . .   7
   6.  ABE Experiment Goals  . . . . . . . . . . . . . . . . . . . .   8
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   9.  Implementation Status . . . . . . . . . . . . . . . . . . . .   9
   10. Security Considerations . . . . . . . . . . . . . . . . . . .   9
   11. Revision Information  . . . . . . . . . . . . . . . . . . . .   9
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  11
     12.2.  Informative References . . . . . . . . . . . . . . . . .  11
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   Explicit Congestion Notification (ECN) [RFC3168] makes it possible
   for an Active Queue Management (AQM) mechanism to signal the presence
   of incipient congestion without necessarily incurring packet loss.
   This lets the network deliver some packets to an application that
   would have been dropped if the application or transport did not
   support ECN.  This packet loss reduction is the most obvious benefit
   of ECN, but it is often relatively modest.  Other benefits of
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