What is User Datagram Protocol (UDP) ?

UDP stands for User Datagram protocol. It is also a transport layer protocol. The protocol number of UDP protocol is 17. In this article, we will discuss features of User Datagram protocol.

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User Datagram Protocol (UDP)

What is the User Datagram Protocol (UDP)?

UDP is a connectionless transport layer protocol, which can transmit data without establishing any connection between sender and receiver. UDP works before the IP protocol. In other words,  Many application layer protocol, encapsulate their header and send it to UDP protocol at the transport layer. Here, UDP encapsulates their own header and thus form a segment and handover it to IP protocol at the Network layer. Though, the word “UDP/IP” is not so common.

In UDP, if senders send the data to the recipient, then there is no such guarantee that the recipient successfully received the data or not. Thus, this protocol is not a reliable protocol. However, there is nothing like reliable messages. Thus, this protocol fast in comparison to TCP.

The header of User Datagram Protocol (UDP)

UDP header has a simpler design in comparison of TCP Header. UDP Header consists of 4 fields, each of which 16 bit. In UDP header, the use of source port and checksum filed is optional in IPv4. In IPv6, the only source filed is optional. Below, is a look of UDP header.

  • Source Port number: It is a 16-bit field, which is optional. Usually, this field contains sender port number.
  • Destination Port Number: It is also a 16-bit field, which is always required. This filed identify as receiving port. Most of the time, this filed contain a port number from well-known ports.
  • Length: Length field specifies the total length of UDP header and UDP data in bytes.
  • Checksum: This field is used for error checking and correction. In IPv4, this field is optional but it IPv6 this field is mandatory. Whenever there is no need for this field, then this field has all zeros.

Application of User Datagram Protocol

Although many application layer protocols, use Transmission Control Protocol as a transport layer protocol, still there are some protocols, which has speed is more important than Reliability. Protocols which needed fast delivery of data is used User Datagram Protocol (UDP). Mainly UDP is used by Dynamic Host Configuration Protocol (DHCP), Domain Name System (DNS), Simple Network Management Protocol (SNMP), Routing Information Protocol (RIP).

Voice and Video traffic mainly used User Datagram Protocol. Because such type of communication not wants delay during transmission of data from source to destination.

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