Characterization Guidelines for Active Queue Management (AQM)
RFC 7928

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Internet Engineering Task Force (IETF)                      N. Kuhn, Ed.
Request for Comments: 7928                        CNES, Telecom Bretagne
Category: Informational                                P. Natarajan, Ed.
ISSN: 2070-1721                                            Cisco Systems
                                                         N. Khademi, Ed.
                                                      University of Oslo
                                                                  D. Ros
                                           Simula Research Laboratory AS
                                                               July 2016

     Characterization Guidelines for Active Queue Management (AQM)

Abstract

   Unmanaged large buffers in today's networks have given rise to a slew
   of performance issues.  These performance issues can be addressed by
   some form of Active Queue Management (AQM) mechanism, optionally in
   combination with a packet-scheduling scheme such as fair queuing.
   This document describes various criteria for performing
   characterizations of AQM schemes that can be used in lab testing
   during development, prior to deployment.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7928.

Kuhn, et al.                  Informational                     [Page 1]
RFC 7928             AQM Characterization Guidelines           July 2016

Copyright Notice

   Copyright (c) 2016 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
   (http://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  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Reducing the Latency and Maximizing the Goodput . . . . .   5
     1.2.  Goals of This Document  . . . . . . . . . . . . . . . . .   5
     1.3.  Requirements Language . . . . . . . . . . . . . . . . . .   6
     1.4.  Glossary  . . . . . . . . . . . . . . . . . . . . . . . .   7
   2.  End-to-End Metrics  . . . . . . . . . . . . . . . . . . . . .   7
     2.1.  Flow Completion Time  . . . . . . . . . . . . . . . . . .   8
     2.2.  Flow Startup Time . . . . . . . . . . . . . . . . . . . .   8
     2.3.  Packet Loss . . . . . . . . . . . . . . . . . . . . . . .   9
     2.4.  Packet Loss Synchronization . . . . . . . . . . . . . . .   9
     2.5.  Goodput . . . . . . . . . . . . . . . . . . . . . . . . .  10
     2.6.  Latency and Jitter  . . . . . . . . . . . . . . . . . . .  11
     2.7.  Discussion on the Trade-Off between Latency and Goodput .  11
   3.  Generic Setup for Evaluations . . . . . . . . . . . . . . . .  12
     3.1.  Topology and Notations  . . . . . . . . . . . . . . . . .  12
     3.2.  Buffer Size . . . . . . . . . . . . . . . . . . . . . . .  14
     3.3.  Congestion Controls . . . . . . . . . . . . . . . . . . .  14
   4.  Methodology, Metrics, AQM Comparisons, Packet Sizes,
       Scheduling, and ECN . . . . . . . . . . . . . . . . . . . . .  14
     4.1.  Methodology . . . . . . . . . . . . . . . . . . . . . . .  14
     4.2.  Comments on Metrics Measurement . . . . . . . . . . . . .  15
     4.3.  Comparing AQM Schemes . . . . . . . . . . . . . . . . . .  15
       4.3.1.  Performance Comparison  . . . . . . . . . . . . . . .  15
       4.3.2.  Deployment Comparison . . . . . . . . . . . . . . . .  16
     4.4.  Packet Sizes and Congestion Notification  . . . . . . . .  16
     4.5.  Interaction with ECN  . . . . . . . . . . . . . . . . . .  17
     4.6.  Interaction with Scheduling . . . . . . . . . . . . . . .  17
   5.  Transport Protocols . . . . . . . . . . . . . . . . . . . . .  18
     5.1.  TCP-Friendly Sender . . . . . . . . . . . . . . . . . . .  19
       5.1.1.  TCP-Friendly Sender with the Same Initial Congestion
               Window  . . . . . . . . . . . . . . . . . . . . . . .  19