TCP/IP Functionality
TCP/IP functionality is divided into four layers, each with its own set of agreed-upon protocols:
The link layer consists of methods and protocols that operate only on a link, which is the network component that interconnects nodes or hosts in the network. Protocols in the layer include Ethernet and Address Resolution Protocol. The internet (or networking) layer connects independent networks to transport the packets containing the data across network boundaries. Protocols are IP and Internet Control Message Protocol. The transport layer handles communications between hosts and is responsible for flow control, reliability, and multiplexing. Protocols include TCP and User Datagram Protocol. The application layer standardizes data exchange for applications. Protocols include HyperText Transfer Protocol, File Transfer Protocol, Post Office Protocol Version 3, Simple Mail Transfer Protocol, and Simple Network Time Protocol.
TCP/IP technically applies to network communications in which the TCP transport is used to deliver data across IP networks. Known as a connection-oriented protocol, TCP works by establishing a virtual connection between two devices through a series of request-and-reply messages sent across the physical network. The average person on the internet works in a predominately TCP/IP environment. Web browsers, for example, use TCP/IP to communicate with web servers. The transfer of information work so seamlessly that millions of people use TCP/IP every day to send email, chat online, and play online games without ever being aware of it.
