Updating TCP to support Rate-Limited Traffic
draft-ietf-tcpm-newcwv-08

The information below is for an old version of the document
Document Type Active Internet-Draft (tcpm WG)
Last updated 2015-02-23
Replaces draft-fairhurst-tcpm-newcwv
Stream IETF
Intended RFC status Experimental
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Send notices to tcpm-chairs@ietf.org, draft-ietf-tcpm-newcwv@ietf.org
TCPM Working Group                                          G. Fairhurst
Internet-Draft                                           A. Sathiaseelan
Obsoletes: 2861 (if approved)                                  R. Secchi
Updates: 5681 (if approved)                       University of Aberdeen
Intended status: Experimental                          February 23, 2015
Expires: August 27, 2015

              Updating TCP to support Rate-Limited Traffic
                       draft-ietf-tcpm-newcwv-08

Abstract

   This document updates RFC 5681 to address issues that arise when TCP
   is used to support traffic that exhibits periods where the sending
   rate is limited by the application rather than the congestion window.
   It provides an experimental update to TCP that allows a TCP sender to
   restart quickly following a rate-limited interval.  This method is
   expected to benefit applications that send rate-limited traffic using
   TCP, while also providing an appropriate response if congestion is
   experienced.

   It also evaluates the Experimental specification of TCP Congestion
   Window Validation, CWV, defined in RFC 2861, and concludes that RFC
   2861 sought to address important issues, but failed to deliver a
   widely used solution.  This document therefore recommends that the
   status of RFC 2861 is moved from Experimental to Historic, and that
   it is replaced by the current specification.

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
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   Drafts is at http://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
   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 August 27, 2015.

Fairhurst, et al.        Expires August 27, 2015                [Page 1]
Internet-Draft                   new-CWV                   February 2015

Copyright Notice

   Copyright (c) 2015 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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Standards Status of this Document . . . . . . . . . . . .   4
   2.  Reviewing experience with TCP-CWV . . . . . . . . . . . . . .   5
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   6
     4.1.  Initialisation  . . . . . . . . . . . . . . . . . . . . .   8
     4.2.  Estimating the validated capacity supported by a path . .   8
     4.3.  Preserving cwnd during a rate-limited period. . . . . . .   9
     4.4.  TCP congestion control during the non-validated phase . .   9
       4.4.1.  Response to congestion in the non-validated phase . .  10
       4.4.2.  Sender burst control during the non-validated phase .  12
       4.4.3.  Adjustment at the end of the non-validated phase  . .  12
     4.5.  Examples of Implementation  . . . . . . . . . . . . . . .  13
       4.5.1.  Implementing the pipeACK measurement  . . . . . . . .  13
       4.5.2.  Implementing detection of the cwnd-limited condition   14
   5.  Determining a safe period to preserve cwnd  . . . . . . . . .  15
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  16
   8.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  16
   9.  Author Notes  . . . . . . . . . . . . . . . . . . . . . . . .  16
     9.1.  Other related work  . . . . . . . . . . . . . . . . . . .  16
     9.2.  Revision notes  . . . . . . . . . . . . . . . . . . . . .  18
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  21
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  21
     10.2.  Informative References . . . . . . . . . . . . . . . . .  22
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  23

1.  Introduction

   TCP is used to support a range of application behaviours.  The TCP
   congestion window (cwnd) controls the number of unacknowledged
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