Understanding the idea of Internet, OSI Model and TCP Model

This is in continuation of our last one article, a new series of networking articles. In this segment, we are going to discuss the idea and incompatibilities in the beginning phase of the Internet and how they were solved.

Individual networks have their own coverage region. The need was felt to expand the coverage region of networks by inter-networking to accomplish worldwide availability to networking. There were difficulties in inter-networking for a worldwide network. Various nations have their own approaches, programs, needs, decisions, and preferences. In that capacity, it was difficult to conquer the jurisdictional limits of various nations to execute the physical interconnection of networks.

Individual networks of various nations are structured dependent on various protocols. The protocols of a network is a set of rules for the practical activity and association of hubs, devices, and PCs to the network. Gateways as devices are one set of tools for settling the issue of nations. Protocol converters are examples of the simplest gateways. For instance, let us expect three individual networks, specifically, a, b and c, are intended for three unique protocols, to be specific, A, B and C, separately. One resolution to fix the inconsistencies of communication between all devices associated in these systems, when interconnected, can be using a few protocol converters, similar to A to B and B to A for communication between systems a and b; B to C and C to B for communication between systems b and c; and A to C and C to A for communication between systems a and c.

So, what will happen when a huge number of computers organizes everywhere throughout the world are connected? Cost-wise, it will be tremendous.

Here comes The Internet

The Internet came as an answer for overall systems of interconnected computer networks to deal with the previously mentioned challenge of worldwide association. It does as such by using a single worldwide protocol known as Internet Protocol (IP) over either Transmission Control Protocol (TCP) or Universal Data Link Protocol (UDP).

TCP IP and UDP/IP are known as protocol suites. The Internet is best characterized as a worldwide system to connect internationally circulated computers to share, trade and give services of the WorldWideWeb (WWW), email, voice, video, informing and interactive media services. The Internet, or essentially the net, may likewise be known as a network of networks. It connects a huge number of Local Area Networks (LANS), Metropolitan Area Networks (MANS), Wide Area Networks (WANS), business and state networks, which are geologically delivered everywhere throughout the globe. For accessing the Internet, clients are required to take the services of a local Internet Service Provider (ISP). An ISP goes about as an agent among clients and the Internet.

The idea of the Internet started in the Advanced Research Projects Agency (ARPA) in the US. It was first actualized in December 1990 in CERN, Switzerland. The development of the Internet is more than the development pace of some other innovation. Here’s a look at how it developed significantly.

UDP/TCP, Understanding the idea of Internet, OSI Model and TCP Model, TechRX
Source: Internet Live Stats (

A protocol defines a set of rules for the functional operation of any computing system. As a part of the process, a protocol settles the issues of incompatibility existing in various frameworks. A protocol is also followed in offices. For instance, an individual secretary follows a prescribed functional protocol to work with the boss and an attendant follows an alternate protocol so that there is no conflict in running the office.

In 1984, the International Standards Organization (ISO) of Europe built up an Open Systems Interconnection (OSI) model for communication in networks. OSI is a layered reference system of standards for communication among various parts of a network and among networks made of various hardware and applications by different vendors.

Incompatibilities are settled by the use of reference model OSI. Throughout the years, OSI has been acknowledged as the fundamental model for inter-computing and networking communications. Most network systems depend on the OSI model. Seven layers of OSI reference model partitions communication into seven peer forms, which are independent of one another. The independent idea of implementing functions in each layer makes the plan adaptable and modular. The function of a layer might be set without influencing the elements of different layers. For implementing the functionality of each layer, a set of rules called Protocol is defined. Every element interacts directly with the layer immediately below it on the transmission end and gives facilities to use by the layer above it. Reasonably, at each layer at the transmitting end, a header is included with payload; and at the receiving end, a header is removed. Elements of the seven layers of the OSI model are :

UDP/TCP, Understanding the idea of Internet, OSI Model and TCP Model, TechRX

The physical layer defines the physical properties (for instance, qualities of signals and codes used for signals) of the different communication media used between a transmitter and a receiver. Physical properties include electrical properties, type of cable used, termination technique, signal coding, etc. Cables might be coaxial, Ethernet, twisted pair or other. The logical bit pipe received from the Data Link Layer is converted into physical signals at the transmitter end. Physical signals received by the receiver are converted back into a logical channel at the receiver end. This makes layer to-layer functionality a peer process.

The data link layer does the logical frame of data bits transmitted/received over the physical layer. At the transmitting end, the layer generates a logical bit pipe with several overheads like the address of source and destination, error checksum, length identification and so on and at the receiving end, the bit pipe is decomposed into received data bits. Data bits are put into a frame that includes headers of address (source and destination), control, checksum.

The network layer performs routing and switching. It describes how data packets/frames traverse over various data links in the network between the source and destination. The layer defines the addressing and routing of the Internet. A node is made up of three layers: physical, datalink and network.

The transport layer takes care of the quality and nature of data delivery. Quality of data delivery refers to issues like fast delivery versus normal delivery.

The session layer manages how to handle packets to be transported by various networks, nodes, and links. It establishes a logical session for transport.

The presentation layer makes the data presentable (encryption/decryption, for example) for transport by syntax, the technique for floating-point numbers and so on.

The application layer defines the type of application of data to be transported. It implements, for example, file system operations.

TCP/IP Model

A protocol suite used on the Internet is made of more than one protocol. TCP/IP, as well as UDP/IP, are both protocol suites developed for the Internet.

The functionality of the TCP/IP model is divided into four layers and TCP/IP is a layered architecture in which each layer is defined according to a specific function to perform. All these four layers work together to transmit the data from one layer to another layer.

Application Layer (Combining Application, Presentation and Session Layers of the OSI Model)

Transport Layer

Internet Layer

Network Interface (Combining Data Link Layer and Physical Layer of the OSI Model)

This is enough for this section, we have talked about the idea of the Internet, how the incompatibilities were solved, the OSI Model and the TCP Model. If you have any suggestions or thoughts, just comment down below.


  • UDP/TCP, Understanding the idea of Internet, OSI Model and TCP Model, TechRX

    My name is Biplab Das. I’m a writer, Blogger, Youtuber and full time IT support engineer whose childhood obsession with science fiction never quite faded. A quarter-century later, the technology that I coveted as a kid is woven into the fabric of everyday life. People say smartphones are boring these days, but I think everyone is beginning to take this wonderful technology marvel for granted.

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