How TCPIP Works

How TCP/IP Works

A TCP/IP network transfers data by assembling blocks of data into packets. Each packet begins with a header containing control information, such as the address of the destination, followed by data. When a file is sent over a TCP/IP network, its contents are sent using a series of different packets. The Internet Protocol (IP) permits applications to run transparently over interconnected networks. When IP is used, applications do not need to know about the hardware being used for the networking. Hence, the same application can run over a local area network (such as Ethernet).

The Transmission Control Protocol (TCP), a transport layer protocol, ensures that data is delivered, that what is received was what was sent, and that packets are received in the order transmitted. TCP will terminate a connection if an error makes reliable transmission impossible.

The User Datagram Protocol (UDP), another transport layer protocol used in the Internet, does not guarantee that packets arrive at their destination. It, therefore, can be used over unreliable communications links because an incomplete packet can be received and the missing portions sent again.

The Internet Protocol Suite also specifies a set of application services, including protocols for electronic mail, file transfer, and terminal emulation. These application service protocols serve as the basis for UNIX commands that carry out a variety of networking tasks.