Concept of DCCP Protocol

During network browsing, we often encounter network cards. The reason may be that the website's data traffic is too large. It is also possible that load balancing is not well done. Here, we will also encounter some content of the DCCP protocol. What is DCCP? DCCP is the data Congestion Control Protocol (DCCP) developed by the Internet Engineering team IETF to propose a new transmission Protocol for UDP in the transport layer, it is used to transmit real-time services. It is a non-reliable transmission protocol that can implement congestion control. It also provides multiple congestion control mechanisms for users to negotiate and select when communication starts. In addition to the reserved and custom methods, DCCP currently defines two congestion control mechanisms: TCP-Like and TFRC. TCP-Like is similar to TCP's AIMD mechanism, while TFRC is a TCP-friendly rate control mechanism.

Establishing, maintaining, and removing unreliable data streams and implementing congestion control over unreliable data streams are two main functions provided by the DCCP protocol. Real-time services require fast and low-cost transmission protocols, so as to minimize the overhead brought by Baotou and the amount of work processed by terminals. Therefore, DCCP should be as simple and reasonable as possible, with low latency and fast response to avoid providing higher-level transmission functions. DCCP does not have the reliability and Sequential transmission features of TCP. Unicast-based applications are also included in DCCP.

MAIN FEATURES OF DCCP

There is a confirmed unreliable datagram stream. Data is transmitted using Data and DataAck. Data is pure Data, and DataAck can have both Data and validation information.

Reliability negotiation. Including suitable Congestion Control Negotiation and congestion control negotiation algorithms. Semi-join. This allows two hosts to be connected using two semi-connections and different congestion control mechanisms. (CCID )). Each CCID illustrates how its terminal responds to the ECN Report. For example, CCID2: TCP-like mechanism and CCID3: TFRC mechanism ).

Applications in multiple connections and mobile communication. The DCCP protocol provides multiple connections. You can notify the other party of the address or port change during the connection process. After the mobile endpoint obtains a new address, it sends the DCCP-Move packet from the new address to the fixed endpoint, and then uses the new address to change the connection status. In addition, DCCP uses a cache to replace TCP probe frames, which reduces network overhead.

In addition, DCCP combines the ECN and ECNNonce congestion control, with the maximum Path Transmission Unit MTU) discovery mechanism; clear connection establishment and suspension process, there is a reliable handshake process for establishing and removing connections. The server can reject any connection attempts without confirmation or an existing connection attempt.

Although there are still many problems with DCCP, for example, the protocol should support both IPv4 and IPv6; in terms of security, whether DCCP can replace UDP in the Transport Security Management Protocol still needs to be discussed; the relationship between the DCCP protocol and the RTP real-time transmission protocol must be further studied, however, the proposal of the Draft DCCP Protocol shows a new service mode for applications that wish to use a protocol to provide multiple transmission services at the same time, it provides a new starting point for the future study of transmission protocols in networks and the support for multimedia applications.