DCCP – Datagram Congestion Control Protocol

DCCP transport layer protocol is used to control the datagram congestion. It provides an excellent procedure to stop the internet fall down, if it is caused by the congestion. In fact, this protocol is a brilliant competitor to be used as a substitute of UDP protocol.

DCCP account DCCP congestion control trait by means of a reliable acknowledgments delivery (in form of packets instead of bytes) will provide actually a congestion control with dynamism. DCCP will also make available the negotiable blocking control mechanism, but it will be up to the particular application’s specific requirements too. Moreover, these mechanisms come with a number of specific features, so to go well with different types of applications. The bandwidth consumption can be enhanced as the size of packets in case of DCCP is increased.

Packet Header The standard size of a DCCP packet header is usually 12 bytes. But this can be increased up to an extent of 1020 bytes. Source Port of 16 bits may represent the connected port of an endpoint that is sending data packets. But destination port of 16 bits is the linked port of another endpoint. Note: These both fields function is to make-out the connection.

Type field  is consisted of 4 bits and it is required to specify the DCCP message type with the values as: request packet, response packet, data packet, ask packet, data ask packet, reset packet, close packet, move packet, etc.

CCval field of 4 bits is kept for the utilization by the transport CCID. Sequence Number field is made of 24 bits and DCCP request packet or else DCCP response packet will be used to initialize it and can increase in value by one as soon as a packet sent to its way. This information will help the recipient in determining that is any packet loss happened or not on the way. Moreover, data Offset is of 8 bits and # NDP are of 4 bits fields.  Checksum is of 16 bits field and Checksum Length or Cslen is of 4 bits field, etc.

DCCP implementations From the mid of 2008, no less than two datagram congestion control protocol implementations are dynamically kept up. The implementation for Linux kernel was first-time provided in 2.6.14 Linux release and the purpose of dccp-tp implementation optimization is its portability. Another latest DCCP implementation “user-space” is in progress. The main aim of this implementation (under the way) is to proffer a handy NAT- welcoming and standardized framework for the communication and contact of peer to peer type along with supple congestion control (based on application too).


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