User Datagram Protocol (UDP)

 

User Datagram Protocol (UDP)

In TCP communications, not only TCP but also UDP (User Datagram Protocol) can meet the functional requirements defined in the transport layer. Unlike TCP, UDP is a connection-less type protocol in which the sending terminal does not check whether data has been received by receiving terminal. In other words, it is a less reliable protocol. However, this protocol makes it possible to omit a variety of processes thus reducing the load on the CPU.

The most important applications that use UDP correspond to the following port numbers:
• 7: echo service;
• 9: Rejection of service;
• 53: DNS domain name server (Dynamic Name Server);
• 67: DHCP configuration server;
• 68: DHCP configuration client.

 

Following is a brief description of each field:

Source Port This is the port number of the application that is originating the user data

Destination Port This is the port number pertaining to the destination application.

Length This field describes the total length of the UDP datagram, including both data and header Information.

UDP Checksum Integrity checking is optional under UDP. If turned on, both ends of the communications channel use this field for data integrity checks.

At this point, it is important to understand the layering concept along with the need for headers.