Quick-Start for the Datagram Congestion Control Protocol (DCCP)
RFC 5634

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Network Working Group                                       G. Fairhurst
Request for Comments: 5634                               A. Sathiaseelan
Category: Experimental                            University of Aberdeen
                                                             August 2009

    Quick-Start for the Datagram Congestion Control Protocol (DCCP)

Abstract

   This document specifies the use of the Quick-Start mechanism by the
   Datagram Congestion Control Protocol (DCCP).  DCCP is a transport
   protocol that allows the transmission of congestion-controlled,
   unreliable datagrams.  DCCP is intended for applications such as
   streaming media, Internet telephony, and online games.  In DCCP, an
   application has a choice of congestion control mechanisms, each
   specified by a Congestion Control Identifier (CCID).  This document
   specifies general procedures applicable to all DCCP CCIDs and
   specific procedures for the use of Quick-Start with DCCP CCID 2, CCID
   3, and CCID 4.  Quick-Start enables a DCCP sender to cooperate with
   Quick-Start routers along the end-to-end path to determine an allowed
   sending rate at the start of a connection and, at times, in the
   middle of a DCCP connection (e.g., after an idle or application-
   limited period).  The present specification is provided for use in
   controlled environments, and not as a mechanism that would be
   intended or appropriate for ubiquitous deployment in the global
   Internet.

Status of This Memo

   This memo defines an Experimental Protocol for the Internet
   community.  It does not specify an Internet standard of any kind.
   Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

Copyright Notice

   Copyright (c) 2009 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 in effect on the date of
   publication of this document (http://trustee.ietf.org/license-info).
   Please review these documents carefully, as they describe your rights
   and restrictions with respect to this document.

Fairhurst & Sathiaseelan      Experimental                      [Page 1]
RFC 5634                  Quick-Start for DCCP               August 2009

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
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   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1. Introduction ....................................................3
      1.1. Terminology ................................................4
   2. Quick-Start for DCCP ............................................5
      2.1. Sending a Quick-Start Request for a DCCP Flow ..............5
           2.1.1. The Quick-Start Interval ............................5
      2.2. Receiving a Quick-Start Request for a DCCP Flow ............6
           2.2.1. The Quick-Start Response Option .....................7
      2.3. Receiving a Quick-Start Response ...........................8
           2.3.1. The Quick-Start Mode ................................8
           2.3.2. The Quick-Start Validation Phase ....................9
      2.4. Procedure When No Response to a Quick-Start Request .......10
      2.5. Procedure When a Packet Is Dropped While Using
           Quick-Start ...............................................11
      2.6. Interactions with Mobility and Signaled Path Changes ......11
      2.7. Interactions with Path MTU Discovery ......................12
      2.8. Interactions with Middleboxes .............................12
   3. Mechanisms for Specific CCIDs ..................................13
      3.1. Quick-Start for CCID 2 ....................................13
           3.1.1. The Quick-Start Request for CCID 2 .................13
           3.1.2. Sending a Quick-Start Response with CCID 2 .........13
           3.1.3. Using the Quick-Start Response with CCID 2 .........13
           3.1.4. Quick-Start Validation Phase for CCID 2 ............14
           3.1.5. Reported Loss or Congestion While Using
                  Quick-Start ........................................14
           3.1.6. CCID 2 Feedback Traffic on the Reverse Path ........15
      3.2. Quick-Start for CCID 3 ....................................15
           3.2.1. The Quick-Start Request for CCID 3 .................15