TCP+IP

TCP IP by Greg Trottier

The internet is a global collection of networks, both big and small. These networks connect together in many different ways to form the single entity that we know as the **Internet**. In fact, the very name comes from this idea of interconnected networks.

TCP/IP is the set of communications protocols used for the Internet and other similar networks. It is named from two of the most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP), which were the first two networking protocols defined in this standard.

TCP/IP is made up of four abstraction layers, which are compared to the seven OSI layers. The layers near the top are logically closer to the user application, while those near the bottom are logically closer to the physical transmission of the data. The top layer is “Application”, next is “Transport”, followed by “Internet”, and “Link”.

The Application layer includes all the processes that use Transport layer protocols to deliver data to the Internet layer. The Transport layer transports data to and from the correct application. This process is known as end-to-end communication. In TCP/IP the Transport layer provides a transport service for application data. Using a routing table, the Internet layer determines the next directly accessible node in route to the packet’s destination. The Link Layer is used to move packets between the Internet Layer interfaces of two different hosts on the same link.