The TCP/IP Protocol Suite

Internet Protocol (IP)

The Internet Protocol (IP) integrates different physical or proprietary networks into a unified logical network known as the Internet.

An IP address is a 32-bit number that specifies both the number for the individual physical network and the number for a given host computer on that network. The term host computer can apply to any end-user computer system that connects to a network. The size of a host can range from an X-terminal or a PC to a large mainframe. Among all the organizations connected to the Internet, the address of each host computer is unique. The address is often written in dotted decimal notation. Dotted decimal notation is the decimal value of each byte (often referred to as an octet in the literature on TCP/IP) separated by a period. For example,

192.22.31.05
is the dotted decimal notation for a machine whose 32-bit address is

0xC0161f05

At the IP protocol layer, host computers cannot be referenced by name. Refer to Domain Name System (DNS) for an explanation of name referencing for host computers. All network communication uses IP addresses. The IP layer routes packets of data to their destinations, which may be many physical hops away from the source of the message. A physical hop is a gateway through which the data must pass. The IP layer does not guarantee that a packet will reach its destination, nor does it provide error checking for the data. The IP layer does not provide flow control or any lasting association (connection) between sender and receiver. A higher layer of the protocol, such as the User Datagram Protocol (UDP) or TCP, must provide all these services.

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