Low Extra Delay Background Transport (LEDBAT)
draft-ietf-ledbat-congestion-09

The information below is for an old version of the document
Document Type Active Internet-Draft (ledbat WG)
Authors Greg Hazel  , Jana Iyengar  , Mirja K├╝hlewind  , Stanislav Shalunov 
Last updated 2012-05-24 (latest revision 2011-10-31)
Replaces draft-shalunov-ledbat-congestion
Stream IETF
Intended RFC status Experimental
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IESG note Murari Sridharan (muraris@microsoft.com) is the Document Shepherd.
Send notices to ledbat-chairs@tools.ietf.org, draft-ietf-ledbat-congestion@tools.ietf.org, shalunov@shlang.com
LEDBAT WG                                                    S. Shalunov
Internet-Draft                                                  G. Hazel
Intended status: Experimental                             BitTorrent Inc
Expires: May 3, 2012                                          J. Iyengar
                                           Franklin and Marshall College
                                                           M. Kuehlewind
                                                 University of Stuttgart
                                                        October 31, 2011

             Low Extra Delay Background Transport (LEDBAT)
                  draft-ietf-ledbat-congestion-09.txt

Abstract

   LEDBAT is an experimental delay-based congestion control algorithm
   that attempts to utilize the available bandwidth on an end-to-end
   path while limiting the consequent increase in queueing delay on the
   path.  LEDBAT uses changes in one-way delay measurements to limit
   congestion that the flow itself induces in the network.  LEDBAT is
   designed for use by background bulk-transfer applications; it is
   designed to be no more aggressive than TCP congestion control and to
   yield in the presence of any competing flows when latency builds,
   thus limiting interference with the network performance of the
   competing flows.

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 http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
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   This Internet-Draft will expire on May 3, 2012.

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Shalunov, et al.           Expires May 3, 2012                  [Page 1]
Internet-Draft                   LEDBAT                     October 2011

   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
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   include Simplified BSD License text as described in Section 4.e of
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   described in the Simplified BSD License.

Table of Contents

   1.  Requirements notation  . . . . . . . . . . . . . . . . . . . .  3
   2.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     2.1.  Design Goals . . . . . . . . . . . . . . . . . . . . . . .  3
     2.2.  Applicability  . . . . . . . . . . . . . . . . . . . . . .  4
   3.  LEDBAT Congestion Control  . . . . . . . . . . . . . . . . . .  4
     3.1.  Overview . . . . . . . . . . . . . . . . . . . . . . . . .  4
     3.2.  Preliminaries  . . . . . . . . . . . . . . . . . . . . . .  5
     3.3.  Receiver-Side Operation  . . . . . . . . . . . . . . . . .  5
     3.4.  Sender-Side Operation  . . . . . . . . . . . . . . . . . .  6
       3.4.1.  An Overview  . . . . . . . . . . . . . . . . . . . . .  6
       3.4.2.  The Complete Sender Algorithm  . . . . . . . . . . . .  6
     3.5.  Parameter Values . . . . . . . . . . . . . . . . . . . . .  9
   4.  Understanding LEDBAT Mechanisms  . . . . . . . . . . . . . . . 11
     4.1.  Delay Estimation . . . . . . . . . . . . . . . . . . . . . 11
       4.1.1.  Estimating Base Delay  . . . . . . . . . . . . . . . . 11
       4.1.2.  Estimating Queueing Delay  . . . . . . . . . . . . . . 12
     4.2.  Managing the Congestion Window . . . . . . . . . . . . . . 12
       4.2.1.  Window Increase: Probing For More Bandwidth  . . . . . 12
       4.2.2.  Window Decrease: Responding To Congestion  . . . . . . 12
     4.3.  Choosing The Queuing Delay Target  . . . . . . . . . . . . 13
   5.  Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . 13
     5.1.  Framing and Ack Frequency Considerations . . . . . . . . . 13
     5.2.  Competing With TCP Flows . . . . . . . . . . . . . . . . . 13
     5.3.  Fairness Among LEDBAT Flows  . . . . . . . . . . . . . . . 14
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 15
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 15
   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     9.1.  Normative References . . . . . . . . . . . . . . . . . . . 16
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