UDP - User Datagram Protocol

The User Datagram Protocol (UDP) is a transport layer protocol defined for use with the IP network layer protocol.UDP is often used in videoconferencing applications or computer games specially tuned for real-time performance.
- UDP network traffic is organized in the form of data grams.A data-gram comprises one message unit. The first eight bytes of a data-gram contain header information and the remaining bytes contain message data.
- UDP can be used in networks where TCP is traditionally implemented.
- It does not guarantee reliability or the correct sequencing of data.
- UDP makes use of a simple communication model without implicit transmission checks for guaranteeing reliability, sequencing, or data-gram integrity.
- UDP considers that error checks and corrections should be carried out in the communicating application, and not at the network layer.
- UDP makes the protocol that much faster and more efficient because it does not have the overhead of checking whether the data has reached the destination every time it is sent.
- UDP is a stateless protocol. UDP is used for packet broadcast or multi-casting whereby the data is sent to all the clients in the network.

The UDP header consists of four fields each of 2 bytes in length :

- Source Port : Source port recognizes the sending port and should be understood to be the port to respond to if required. If not used, then its value should be zero.

- Destination Port : UDP packets from a client use this as a service access point (SAP) to indicate the service required from the remote server.

- UDP length : The number of bytes comprising the combined UDP header information and payload data.

- UDP Checksum : A checksum to verify that the end to end data has not been corrupted by routers or bridges in the network or by the processing in an end system.