Concept Of OSI Models, What are the 7 Layers of the OSI Models? (Lession- 24)

OSI Models

The acronym System Interconnection OSI Models stands for OSI Models Open refers to non-proprietary. It is an architecture consisting of seven layers, each with a distinct set of functions to carry out. All seven of these levels work together to transmit data from one person to another across the world. ISO, which stands for “International Organization for Standardization,” was the organization that came up with the OSI Models reference model in 1984.

The Open Systems Interconnection OSI Models paradigm provides a theoretical basis for comprehending network communication. However, real-world networking hardware or software often does not immediately implement it in its entirety. Specialized protocols and technologies often build on the concepts of the Open Systems Interconnection OSI Models paradigm to facilitate efficient data transfer and networking activities.

The International Organization for Standardization (ISO) developed the Open Systems Interconnection OSI Models paradigm in 1984 to explain data transmission between computers. Its compartmentalization into seven levels, each collaborating with the others to carry out a specific network function, enables a more methodical approach to networking.

What are the 7 Layers of the OSI Model?

Physical Layer – Layer 1

In the Open Systems Interconnection OSI Models reference model, the physical layer is the lowest layer. In other words, it is responsible for the actual physical link between the devices. The physical layer includes bits as the units of information. This component is responsible for transmitting individual bits from one node to another. This layer receives the received signal, converts it into 0s and 1s, and then transfers it to the Data Link layer, which reassembles the frame.

Data Link Layer (DLL) – Layer 2

The data connection layer is responsible for ensuring the delivery of messages from one node to another. The primary purpose of this layer is to guarantee that the flow of data from one node to another, which occurs across the physical layer, is uninterrupted and free of errors. Whenever a packet comes into a network, it is the duty of the DLL to send it to the host by using the host’s Media Access Control (MAC) address. 

Network Layer – Layer 3

The data connection layer is responsible for ensuring the delivery of messages from one node to another. The primary purpose of this layer is to guarantee that the flow of data from one node to another, which occurs across the physical layer, is uninterrupted and free of errors. Whenever a packet comes into a network, it is the duty of the DLL to send it to the host by using the host’s Media Access Control (MAC) address. 

Transport Layer – Layer 4

The application layer receives services from the transport layer, whereas the transport layer receives services from the network layer that it offers. The transport layer names the data it includes as segments. Its responsibilities encompass delivering the entire message from start to finish. Additionally, the transport layer is responsible for providing an acknowledgement of the successful transfer of data and for re-transmitting the data in the event that a mistake is discovered.

Session Layer – Layer 5

It is the responsibility of this layer to create connections, maintain sessions, and authenticate users. It also bears the responsibility of maintaining security.

Presentation Layer – Layer 6

There is another name for the presentation layer, which is the translation layer. At this stage, we remove and alter the data derived from the application layer to conform to the necessary format for network transmission.

Application Layer – Layer 7

When we look at the stack of layers that make up the OSI Reference Model, we discover the application layer at the very top. The network applications implement this layer. These applications generate the information that will travel across the network. Furthermore, this layer serves as a window for application services to communicate with the network and display the received information to the user.

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