20.5 USER DATAGRAM PROTOCOL (UDP)

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The TCP provides a reliable service by taking care of error control and flow control. However, the processing required for the TCP layer is very high and is called a heavyweight protocol. In some applications such as real-time voice/video communication and network management, such high processing requirements create problems. Another transport protocol is used for such applications. That is user datagram protocol (UDP). UDP provides a connectionless service. It sends the packets to the destination one after the other, without caring whether they are being received correctly or not. It is the job of the application layer to take care of the problems associated with lack of acknowledgements and error control. Simple Network Management Protocol (SNMP), which is used for network management, runs above the UDP.

To provide reliable service, the TCP layer does lots of processing, and hence it is called a heavy-weight protocol. The UDP is another transport layer that provides connectionless service. Processing of UDP packets is much faster.

Note

In applications such as real-time voice communications, if a packet is lost, there is no point in asking for a retransmission because it causes lots of delay. For such applications, UDP is a better choice than TCP.

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