User Datagram Protocol (udp)

User Datagram Protocol (UDP) is an alternative communications protocol to Transmission Control Protocol (TCP) used primarily for establishing loss tolerant connections between two applications on the Internet. Both UDP and TCP run on top of the Internet Protocol (IP) in the transport layer and are sometimes referred to as UDP/IP or TCP/IP. Both protocols send short packets of data in the form of datagrams.

In recent times, Transmission Control Protocol has emerged as the dominant protocol used for the bulk of internet connectivity due to services such as breaking large data sets into individual datagrams, checking for acknowledgements and resending lost packets and reassembling packets into the correct sequence. But these services come at a cost in terms of additional data overhead, and delays. In contrast, user data protocol just forwards the packets without acknowledgements and resending services, effectively reducing bandwidth overhead and latency issues. But packets can be lost or received out of order as a result, owing to the different paths individual packets traverse between sender and receiver.

It provides two additional services over the Internet Protocol layer. It provides port numbers to help distinguish different user requests and, a checksum calculation capability to verify that the data arrived intact. In UDP connection, client set unique source port numbers based on the program they started connection. UDP is not limited to 1-to-1 interaction. A 1-to-many interaction can be provided using broadcast or multi-cast addressing. A many-to-1 interaction can be provided by many clients communicating with a single server. A many-to-many interaction is just an extension of these techniques.

UDP is an attractive option for applications which have small latency as their critical requirement. These applications could range from voice and video communication to real time gaming and video streaming. These applications would compromise on some lost data as long as the received quality is up to the required standards. In some cases, error correction techniques might be required to improve quality of transmission. Some important characteristics of UDP transmission are given below:

1. It is an end to end connectionless delivery protocol.
2. It is unreliable as the communication set up only consists of data packets without any acknowledgements.
3. Just as Internet Protocol it’s a best effort network.
4. It can be used for real time applications as it’s a real time transport protocol. UDP transmits segments consisting of an 8-byte header.

Its contains Source port, Destination port, UDP length and Checksum. UDP checksum used for detecting errors in transmitted segment.