What Is OSI Model? A Basic Overview In 2021


At whatever point you connect two devices either on the equivalent or various networks, a question may emerge in your connectivity concerning the availability of the devices. The two devices may have diverse architecture and actualize various protocols, at that point, how might they connect and offer information. The layers of OSI are divided into 7 parts.

Open System Interconnection or OSI is a reference model that portrays how information from a software application in one computer goes through an actual medium to the software application in another computer.

What is OSI model purpose? The purpose of the OSI model is to normalize data networking protocols to permit correspondence between all networking administration gadgets across the whole planet.

  1. Characteristics of the OSI Model
  2. Functions of the OSI Layers
  3. What is OSI model and TCP/IP model? 
  4. What is OSI model in ISO? 
  5. What is OSI model, and how it works?

1. Characteristics of the OSI Model

Characteristics of the OSI Model
Application Layer

Responsibility of the Host
Presentation Layer
Session Layer
Transport Layer
Network Layer

Responsibility of the Network
Data-Link Layer
Physical Layer
  • The OSI model is separated into two layers: 
  1. Upper Layer: The upper layer of the OSI model, for the most part, manages application-related matters, and they are actualized uniquely in the software. The application layer is nearest to the end-user.
  2. Lower Layer: The lower layer of the OSI model arrangements with data transport matters. The physical layer and the data link layer are actualized in software and hardware.

2. Functions of the OSI Layers

There are 7 layers of the OSI model, and each layer has various functions:

Layer Name of Layer Function
Layer 7 Application Human-computer interaction, where the application can get network services.
Layer 6 Presentation Guarantees that data is in a usable format and is the place where data encryption happens.
Layer 5 Session It is utilized to establish, manage & terminate the sessions.
Layer 4 Transport Transmit data using transmission protocols, including UDP & TCP.
Layer 3 Network It is liable for moving the packets from the source to the destination.
Layer 2 Data-Link Characterizes the format of data on the network.
Layer 1 Physical It provides a physical medium through which bits are transmitted.
  • Physical Layer in the OSI Model:

The physical layer defines the methods for transmitting raw bits over a physical data link connecting network nodes.


  1. The Physical Layer is the lowest layer of the OSI Model.
  2. It changes over the analogue/digital pieces into an electrical sign or optical signs.
  3. It characterizes the way how network devices are designed.
  • Data-Link in the OSI Model:

The data link layer gives the practical and procedural intends to move data between network entities. It might give the way to identify and perhaps correct mistakes that may happen in the physical layer. 


  1. Receiving and transmitting data outlines consecutively is overseen by this layer.
  2. It contains two sub-layers, for example, media access control layer and the logical link control layer.
  3. It characterizes the configuration of the data on the network.
  • Network in the OSI Model:

The network layer is answerable for getting frames from the data link layer and conveying them to their expected destinations, dependent on them tends to contained inside the frame. 


  1. It goes about as a network regulator.
  2. It chooses which route data should take.
  3. It deals with Subnet traffic.
  • Transport in the OSI Model: 

It gives a straightforward transfer of data between end-users, giving secure data move services to the upper layers. 


  1. It tends to be extremely complicated, contingent on the network necessities.
  2. The fundamental obligation of the transport layer is to move the data.
  3. The two protocols utilized in this layer are the user datagram protocol and transmission control protocol.
  • Session in the OSI Model:

It gives the tool for managing, closing, and opening a session between end-user application measures. 


  1. It synchronizes and manages the discussion between two unique applications.
  2. It goes about as a dialogue regulator that makes a dialogue between two cycles.
  3. It adds a few checkpoints when communicating the data in an arrangement.
  • Presentation in the OSI Model:

It is utilized to present data to the application layer in an exact, all around characterized and standardized format.


  1. It performs data conversion, data encryption, data compression and so on.
  2. It goes about as a data translator for a network.
  3. Encryption is expected to look after protection.
  • Application in the OSI Model: 

It is an abstraction layer that indicates the common communications protocols and interface techniques utilized by hosts in a communications network. 


  1. It gives disseminated database sources.
  2. It is the highest layer.
  3. This layer essentially holds application projects to follow up on the received and to be sent data.

3. What is OSI model and TCP/IP model? 

OSI model is a generic model that depends on the functionalities of each layer, while the TCP/IP model is a protocol situated norm.

4. What is OSI model in ISO? 

ISO represents the International Organization of Standardization. This is known as a model for Open System Interconnection and is regularly known as the OSI model.

5. What is OSI model, and how it works?

OSI model is a layered structure that permits communication between a wide range of the PC framework, and it has seven layers.


OSI model partitions the entire undertaking into seven more modest and sensible tasks, and each layer is allocated a specific task.

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