Profile for Datagram Congestion Control Protocol (DCCP) Congestion Control ID 3: TCP-Friendly Rate Control (TFRC)
RFC 4342

Network Working Group                                           S. Floyd
Request for Comments: 4342                                          ICIR
Category: Standards Track                                      E. Kohler
                                                                    UCLA
                                                               J. Padhye
                                                      Microsoft Research
                                                              March 2006

        Profile for Datagram Congestion Control Protocol (DCCP)
       Congestion Control ID 3: TCP-Friendly Rate Control (TFRC)

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   This document contains the profile for Congestion Control Identifier
   3, TCP-Friendly Rate Control (TFRC), in the Datagram Congestion
   Control Protocol (DCCP).  CCID 3 should be used by senders that want
   a TCP-friendly sending rate, possibly with Explicit Congestion
   Notification (ECN), while minimizing abrupt rate changes.

Table of Contents

   1. Introduction ....................................................2
   2. Conventions .....................................................3
   3. Usage ...........................................................3
      3.1. Relationship with TFRC .....................................4
      3.2. Half-Connection Example ....................................4
   4. Connection Establishment ........................................5
   5. Congestion Control on Data Packets ..............................5
      5.1. Response to Idle and Application-Limited Periods ...........7
      5.2. Response to Data Dropped and Slow Receiver .................8
      5.3. Packet Sizes ...............................................9
   6. Acknowledgements ................................................9
      6.1. Loss Interval Definition ..................................10
           6.1.1. Loss Interval Lengths ..............................12
      6.2. Congestion Control on Acknowledgements ....................13

Floyd, et al.               Standards Track                     [Page 1]
RFC 4342                    DCCP CCID3 TFRC                   March 2006

      6.3. Acknowledgements of Acknowledgements ......................13
      6.4. Determining Quiescence ....................................14
   7. Explicit Congestion Notification ...............................14
   8. Options and Features ...........................................14
      8.1. Window Counter Value ......................................15
      8.2. Elapsed Time Options ......................................17
      8.3. Receive Rate Option .......................................17
      8.4. Send Loss Event Rate Feature ..............................18
      8.5. Loss Event Rate Option ....................................18
      8.6. Loss Intervals Option .....................................18
           8.6.1. Option Details .....................................19
           8.6.2. Example ............................................20
   9. Verifying Congestion Control Compliance with ECN ...............22
      9.1. Verifying the ECN Nonce Echo ..............................22
      9.2. Verifying the Reported Loss Intervals and Loss
           Event Rate ................................................23
   10. Implementation Issues .........................................23
      10.1. Timestamp Usage ..........................................23
      10.2. Determining Loss Events at the Receiver ..................24
      10.3. Sending Feedback Packets .................................25
   11. Security Considerations .......................................27
   12. IANA Considerations ...........................................28
      12.1. Reset Codes ..............................................28
      12.2. Option Types .............................................28
      12.3. Feature Numbers ..........................................28
   13. Thanks ........................................................29
   A. Appendix: Possible Future Changes to CCID 3 ....................30
   Normative References ..............................................31
   Informative References ............................................31

List of Tables

   Table 1: DCCP CCID 3 Options ......................................14
   Table 2: DCCP CCID 3 Feature Numbers ..............................15