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7 Layers of the OSI Model | OSI Model | What is the OSI Model – Explained

7 Layers of the OSI Model :- If you are studying computer networking, it is very important to understand the OSI model.

Although the OSI model is very easy to understand, sometimes some people do not understand the OSI model quickly.

And if you are a networking student and you go to interview somewhere, then the interviewer definitely asks you about the OSI model.

So guys, today I will explain you about the OSI model and its 7 layers in a very easy way.

What is the OSI Model ?

The full form Of OSI model is (OPEN SYSTEM INTERCONNECTION).

OSI model was developed by the International Organization for Standardization (ISO) in 1984.

It is a model for understanding data communication between two or more networking devices.

It divides the communication process into seven separate layers.

Each layer perform specific functions.

There are following 7 layers of OSI model.

7 Layers of the OSI Model

7 Layers of the OSI Model

Layer 7 Application Layer

The application layer allow a user to access the information over the network using an application,

and provides an interface for the end user to operate a device connected to a network.

Application layer functions:

  • Network virtual terminal
  • File Transfers Access and Management (FTAM)
  • Ability to print on a network
  • Electronic mail
  • Browsing the World Wide Web
  • Directory Service

Layer 6 Presentation Layer

The presentation layer, is responsible for how an application formats the data to be sent out onto the network.

The presentation layer basically allows an application to read (or understand) the message.

Presentation Layer functions:

  • Translation
  • Encryption
  • Compression

Layer 5 Session Layer

The session layer, provides various services, including tracking the number of bytes that each end of the session has acknowledged receiving from the other end of the session.

Session layer is responsible for establishing, maintaining and terminating Session.

Session layer functions:

  • Dialog Control
  • Synchronization

Layer 4 Transport Layer

The transport layer of the OSI model, offers end-to-end communication between end devices through a network.

It is also known as heart of OSI.

Transport layer functions:

  • Identifying Service
  • Service Point Addressing
  • Segmentation and reassembly
  • Connection control
  • Flow Control
  • Error control

Layer 3 Network Layer

Network layer is responsible for best path for data to reach the destination.

The network layer of the OSI model, provide end-to-end logical addressing system.

Networking Router is the Network Layer device.

Related Topic :- What is Router – Types Of Router & Classifications

Transport layer functions:

  • Logical addressing
  • Routing
  • Handling Congestion issue

Layer 2 Data Link Layer

This is the second layer of OSI model. Data unit at this layer is called as “frame”.

Data Link Layer functions:

  • Framing
  • Physical Addressing
  • Access Control
  • Flow Control
  • Error Control

Layer 1 Physical layer

Physical layer is the first or bottom most layer of the OSI model.

It define the electrical and mechanical specifications like cables, connectors and signaling option of the medium.

Physical Layer functions:

  • Characteristics of media
  • Encoding
  • Transmission rate
  • Transmission mode
  • Topology
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