The Datagram Congestion Control Protocol (DCCP) Service Codes
RFC 5595

Network Working Group                                       G. Fairhurst
Request for Comments: 5595                        University of Aberdeen
Updates: 4340                                             September 2009
Category: Standards Track

     The Datagram Congestion Control Protocol (DCCP) Service Codes

Abstract

   This document describes the usage of Service Codes by the Datagram
   Congestion Control Protocol, RFC 4340.  It motivates the setting of a
   Service Code by applications.  Service Codes provide a method to
   identify the intended service/application to process a DCCP
   connection request.  This provides improved flexibility in the use
   and assignment of port numbers for connection multiplexing.  The use
   of a DCCP Service Code can also enable more explicit coordination of
   services with middleboxes (e.g., network address translators and
   firewalls).  This document updates the specification provided in RFC
   4340.

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.

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Fairhurst                   Standards Track                     [Page 1]
RFC 5595                   DCCP Service Codes             September 2009

   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
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   than English.

Table of Contents

   1. Introduction ....................................................3
      1.1. History ....................................................3
      1.2. Conventions Used in This Document ..........................6
   2. An Architecture for Service Codes ...............................6
      2.1. IANA Port Numbers ..........................................6
      2.2. DCCP Service Code Values ...................................7
           2.2.1. New Versions of Applications or Protocols ...........8
      2.3. Service Code Registry ......................................8
      2.4. Zero Service Code ..........................................9
      2.5. Invalid Service Code .......................................9
      2.6. SDP for Describing Service Codes ...........................9
      2.7. A Method to Hash the Service Code to a Dynamic Port ........9
   3. Use of the DCCP Service Code ...................................10
      3.1. Setting Service Codes at the Client .......................11
      3.2. Using Service Codes in the Network ........................11
      3.3. Using Service Codes at the Server .........................12
           3.3.1. Reception of a DCCP-Request ........................13
           3.3.2. Multiple Associations of a Service Code
                  with Ports .........................................14
           3.3.3. Automatically Launching a Server ...................14
   4. Security Considerations ........................................14
      4.1. Server Port Number Reuse ..................................15
      4.2. Association of Applications with Service Codes ............15
      4.3. Interactions with IPsec ...................................15
   5. IANA Considerations ............................................16
   6. Acknowledgments ................................................16
   7. References .....................................................17