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In this article:
- What is the Internet Protocol Suite
- Background and History of the Internet Protocol Suite
- Layers under the Internet Protocol Suite
What is the Internet Protocol Suite?
The set of communications protocol on which the Internet and other such netoworks work is termed as the Internet Protocol Suite. It may also be referred to as the TCP/IP protocol suite since TCP (Transmission Control Protocol) and IP (Internet Protocol) are the most important and well-known protocols in the suite.
The Internet protocol suite is a set of layers, placed on top of one another. Each layer has its own functions. Each layer provides its services to the layer exactly above it and takes the services from the layer exactly below it. While the upper layers are what the user deals with mostly, the lower layers translate the data collected above to something which can be transmitted over a network, physically.
Background and history of the Internet Protocol Suite
The Internet protocol suite originated at DARPA in the early 1970s which had already built the first network, the ARPANET. Robert E. Kahn who was hired at DARPA in 1972, worked on satellite packet networks and ground-based radio packet networks and had shown the importance of being able to communicate across them. Vinton Cerf joined him in 1973 to work on open-architecture an interconnection model which was to be the next protocol for the ARPANET.
By 1973, Kahn and Cerf had made a fundamental reformulation, where the differences between the various network protocols were hidden by a common internetwork protocol. Now, the responsibility of the reliability of the network was put opn the hosts rather than the network itself.
This limited role of the network made it possible to connect any network to any other network irrespective of the differences between them. A gateway (now called a router) which is a computer is present that interfaces with each of the networks and and forwards packets to and fro between them.
DARPA along with BBN, Stanford, and The University College London developed operational versions of the protocol. This led to the various versions from TCP v1, TCP v2, TCP v3 and IP v3 to finally result into TCP/IP v4 -- the standard protocol in use today.
Initial tests in 1975 involved two-networks between Stanford and University College London (UCL). In November, 1977, a three-network TCP/IP test was done between the U.S., U.K., and Norway. Until 1983, various avatars and prototypes were tested. On January 1, 1983, the ARPANET made a complete switchover to TCP/IP.
Layers under the Internet Protocol Suite
As against the so-called standard in the industry, the OSI reference model, the Internet Protocol Suite has only four layers, each of which is described below:
- Application Layer
The data sent from this layer is application specific, that is, unique to the application sending the data and is encapsulated into a transport layer protocol and the layer makes use of what are called libraries. The data to be sent through the network is passed on to the lower layer protocol in the tranport layer after encapsulation. Common protocols in the lower layer include TCP and UDP and require the use of software ports.
- Transport Layer
The transport layer performs two major functions. Firstly, it is responsible for end-to-end message transfer and secondly, it is responsible for error control, fragmentation and flow control in the network.
The transport layer uses ports to enalbe the service of connecting applications together. Address reliability begins at this layer.
- Network Layer
The Network layer is responsible for the packets to go across a single network. Additionaly, it has gets the data from the source network and sends it to the destination network (this is done by IP at the network level). This process is completed by routing of packets over a kind of web of networks.
- Link Layer
This layer is not actually a part of the Internet Protocol Suite. Rather, it is way to pass packets from the network layer located on two different hosts. The IP can run over many link layers at the same time and the process of transmitting the packets can be implemented through software or firmware or even hardware. The layer is responsible for adding packet headers and then transmitting the data in form of frames.
Sometimes, the physical layer, that is, the hardware used to connect networks and communicate between them, may also be considered as part of the link layer.
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