The DCCP Service Code

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.