Datagram Congestion Control Protocol

from Wikipedia, the free encyclopedia
DCCP in the TCP / IP protocol stack :
application Streaming protocol
transport DCCP
Internet IP ( IPv4 , IPv6 )
Network access Ethernet Token
bus 		Token
ring 		FDDI ...

The Datagram Congestion Control Protocol ( DCCP for short ) is a network protocol of the transport layer . It is used, for example, to transmit media streams in IP networks when a congestion control mechanism (for dynamic adaptation of the transmission rate to the actually available data transmission rate ) is to be used. The TCP protocol , which is otherwise frequently used for this , has disadvantages in the timely delivery of "real-time data" - for example through its forced confirmations .

Features and functions

DCCP was developed in such a way that an application can be easily converted from UDP to DCCP. For this purpose, the necessary range of functions was kept to a minimum and additional functions were moved to higher layers . It can be used with any application which unreliable unicast connections with overload control (engl. Congestion control ) are required. DCCP allows the application to choose the appropriate overload control mechanism for the respective application.

Datagram Congestion Control Protocol Header

DCCP header with 48-bit sequence number
0 1 2 3 4th 5 6th 7th 8th 9 10 11 12 13 14th 15th 16 17th 18th 19th 20th 21st 22nd 23 24 25th 26th 27 28 29 30th 31
Source port Destination port
Data offset CCVal CsCov Checksum
Res Type 1 reserved Sequence number (more significant bits)
Sequence number (low order bits)
DCCP header with 24-bit sequence number
0 1 2 3 4th 5 6th 7th 8th 9 10 11 12 13 14th 15th 16 17th 18th 19th 20th 21st 22nd 23 24 25th 26th 27 28 29 30th 31
Source port Destination port
Data offset CCVal CsCov Checksum
Res Type 0 Sequence number (low order bits)

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