Datagram Congestion Control Protocol

The Datagram Congestion Control Protocol ('''DCCP''') is a message-oriented Transport Layer Protocol that is currently under development in the IETF .

Applications that might make use of DCCP include those with timing constraints on the delivery of data such that reliable in-order
delivery, when combined with Congestion Control , is likely to result
in some information arriving at the receiver after it is no longer
of use. Such applications might include Streaming Media and
Internet Telephony . Congestion control is the way that a network protocol
discovers the available network capacity on a particular path. The primary motivation
for the development of DCCP
is to provide a way for such applications to gain access to standard congestion
control mechanisms without having to implement them at the application layer.

DCCP is intended for applications that require the flow-based
semantics of TCP , but which do not want TCP's in-order delivery and
reliability semantics, or which would like different congestion
control dynamics than TCP. Similarly, DCCP is intended for
applications that do not require features of SCTP such as
sequenced delivery within multiple streams.

To date most such applications have used either TCP, with the
problems described above, or used UDP and implemented their own
congestion control mechanisms (or no congestion control at all).
The purpose of DCCP is to provide a standard way to implement
congestion control and congestion control negotiation for such
applications. One of the motivations for DCCP is to enable the use
of ECN , along with conformant end-to-end congestion control, for
applications that would otherwise be using UDP. In addition, DCCP
implements reliable connection setup, teardown, and feature
negotiation.

A DCCP connection contains acknowledgement traffic as well as data
traffic. Acknowledgements inform a sender whether its packets
arrived, and whether they were ECN marked. Acks are transmitted as
reliably as the congestion control mechanism in use requires,
possibly completely reliably.

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Datagram Congestion Control Protocol