The User Datagram Protocol (UDP) is a very simple layer over the host-to-host Internet Protocol (IP). It only adds 16-bit source and destination port numbers for multiplexing between different applications on the pair of hosts, and 16-bit length and checksum fields. It has been defined in RFC 768.
UDP is used directly for protocols such as the Domain Name System (DNS) or the Network Time Protocol (NTP), which consists on isolated request-response transactions between hosts, where the negotiation and maintenance of TCP connections would be prohibitive.
There are other protocols layered on top of UDP, for example the Real-time Transport Protocol (RTP) used in real-time media applications. UDT,VFER, RBUDP, Tsunami, and Hurricane are examples of UDP-based bulk transport protocols.
– Main.SimonLeinen - 31 Oct 2004 - 02 Apr 2006