Transmission Control Protocol (TCP)
TCP The most common transport layer protocol used on Ethernet and the
TCP is the connection-oriented protocol built on top of Internet
Protocol (IP) and is nearly always seen in the combination TCP/IP (TCP
over IP). It adds reliable communication and flow-control and provides
full-duplex, process-to-process connections.
User Datagram Protocol (UDP)
The User Datagram Protocol (UDP) is a TCP/IP standard defined in RFC
768. UDP is used by some programs instead of TCP for fast,
lightweight, unreliable transportation of data between TCP/IP hosts.
UDP provides a connectionless datagram service that offers best-effort
delivery, which means that UDP does not guarantee delivery or verify
sequencing for any datagrams. A source host that needs reliable
communication must use either TCP or a program that provides its own
sequencing and acknowledgment services.
In general, differences in how UDP and TCP deliver data are similar to
the differences between a telephone call and a postcard. TCP works like
a telephone call by verifying that the destination is available and
ready to communicate. UDP works like a postcard—messages are small and
delivery is likely, but not always assured.
UDP is typically used by programs that transmit small amounts of data at
one time or have real-time requirements. In these situations, the low
overhead and multicasting capabilities of UDP (for example, one
datagram, many recipients) are better suited than TCP.
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