Page 177 - DCAP207_NETWORKS_DCAP406_COMPUTER_NETWORKS

Computer Networks/Networks

Notes
Figure 11.1: Example Finite State Model

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11.3.4 User Datagram Protocol (UDP)

The User Datagram Protocol enables application programs to have direct access to a datagram
delivery service like the delivery service that IP provides. This enables applications to exchange
messages over the network with a minimum of protocol overhead. UDP is connectionless
unreliable datagram protocol in which the sending terminal does not check whether data has
been received by receiving terminal. The unreliable service indicates that there is no guarantee
that the data reaches at the receiving end of the network correctly. It can be understood more
clearly by Figure 11.2.
However, this protocol makes it possible to omit a variety of processes thus reducing
the load on the CPU. UDP has 16-bit Source Port and Destination Port numbers. Figure 11.3 shows
the data structure of the UDP header. The simplicity of the UDP header stems from the
unsophisticated nature of the services it provides.
Figure 11.2: Comparison between TCP and UDP

Reliability
TCP

UDP

Processing Time

Figure 11.3: Format of the UDP Datagram
0 16 31
Source Port Destination Port
Length UDP Checksum
Data

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