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

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.

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   document authors.  All rights reserved.

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

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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