What is OSI Model ?

The OSI Model -

Before learning about the detailed structure of the model and its seven layers, given below are a few points of introduction related to the Open Systems Interconnection Model which one must know.?

>>In the 1970s the OSI Model was proposed and in the year 1984, it was published by the International Organization of Standardization (ISO)

>>Using this model, troubleshooting has become easier as the error can be detected at different levels

>>This also helps in understanding the relationship and function of the software and hardware of a computer network

>>The concept that the OSI Model should be a seven-layer structure, was proposed by Charles Bachman at Honeywell Information Systems

>>The model initially did gain much popularity as it could not support the Internet protocol suite which was not acceptable to a lot of IT Companies

>>The seven layers of the structure are divided into two part: the upper layer or the host layer and lower layer or the media layer

1. Physical Layer

It is the bottom-most or the first layer of the OSI Model

It comprises the raw data which is further transmitted to the higher layers of the structure

Preparing the physical devices in the network and accepting the received data for transmission

The termination of connection between two nodes of a network also takes place at this stage

This layer converts the digital bits into electrical, radio, or optical signals

2. Data Link Layer

Access to get the data is achieved at this layer

It breaks the input data into frames which makes analyzing the data easier

Ensures that the data received is free of any errors

It controls the flow of data in the stipulated time duration and along with a set speed of transmission

The data is sent to the next layer in the form of packets which are then reviewed for further processing

3. Network Layer

It acts as a network controller

Transferring of variable data from one node to another, connected in a network, takes place at this layer?

Each node has a specific address and the network layer ensures that the data is sent to its destination address

The data is sent in the form of fragments which are then connected to each other once the processing is done

4. Transport Layer

The delivery of data packets is managed by the transport layer

It manages the flow of data, segmentation and desegmentation and error control

There are five classes of the transport protocol, starting from 0 and continuing till 4 (TP0 to TP4)

Fragmentation and reassembly of data packets occur that this stage

5. Session Layer

The connection between the computers connected in a network is managed at this layer

Establishment, management and termination between the remote and local application takes place here

Authentication and authorization happen at this layer

This layer can also terminate or end any session or transmission which is complete

6. Presentation Layer

The data is converted into the syntax or semantics which an application understands

Before passing on the data any further, the data is formatted at this stage

Functions including compression, encryption, compatible character code set, etc. are also done at this layer of the model

It serves as a data translator for the network

7. Application Layer

The interaction with the user or the user application takes place at this stage

When identifying communication partners, the application layer determines the identity and availability of communication partners for an application with data to transmit

On the whole, the entire process of transfer of raw data into processed data and finally to the user or the application can be done through this OSI model. It can detect errors, transmit the data and format it during the course of the above-mentioned seven layers