UDP (User Datagram Protocol)

UDP Protocol

UDP Protocol (User Datagram Protocol) is another Tranport Layer Protocol. It is simpler than TCP. We will also see the differences of these two protocols in TCP vs UDP lesson. It is generally used in unsenstive communications and real time applications that do not need a secure data transmission mechanims. For example live video conference, voice traffiv and gaming applications are the services in which UDP Protocol is used.

UDP is a Connectionless Protocol. There is no need to establish a session to use UDP. For TCP, as we have talked about before, a session must be established with Three-Way Handshake.

UDP is not a Reliable protocol. UDP do not care about if the data is received or not. Generally applications that provide its own Error-recovery, use UDP. This make UDP, a Best Effort (fast) protocol. So, generally UDP used for real time applications, that need fast and efficient transmission such as voice calls, video calls, games etc.

UDP is susceptible to the data loses, duplicate traffic and non-orderly delivery. It only concentrate on Best-Effort (Fast) transmission.

There is no Ordering Mechanism in UDP. If any order is required, the Application Layer do this for that traffic.

UDP Header

UDP Protocol Header has a fixed ans simple header. The total length of UDP Protocol Header is 8 Bytes. This length is variable for TCP. A TCP header  length can be a value between 20 and 60 Bytes.

So, what are the fields of this UDP Header? There are :

• 16 bits Source Port,
• 16 bits Destination Port,
• 16 bits Length field
• 16 bits Checksum field.