User Datagram Protocol (UDP)
UDP, documented in RFC 768, provides users access to IP-like services. UDP packets are delivered just like IP packets - connection-less datagrams that may be discarded before reaching their targets. UDP is useful when TCP would be too complex, too slow, or just unnecessary.UDP provides a few functions beyond that of IP:
- Port Numbers. UDP provides 16-bit port numbers to let multiple processes use UDP services on the same host. A UDP address is the combination of a 32-bit IP address and the 16-bit port number.
- Checksumming. Unlike IP, UDP does checksum its data, ensuring data integrity. A packet failing checksum is simply discarded, with no further action taken.