OSI Model in Data Communication and Networking

Oct 26 • Notes • 9350 Views • 1 Comment on OSI Model in Data Communication and Networking

Computer Users are located over a worldwide physical range. Therefore, in order to ensure that nationwide and world wide communication system can be developed ans are compatible to each other, an international group of standards are developed. These standards will fit into a framework which has been developed by the (ISO) “International Organisation of Standardization”. This model is also called as “Model for Open System Interconnection” and is often called as “OSI Reference Model”. This post present, Data Communication and Networking notes on OSI Model in details. Hope this will help you to understand the concept in a well manner. Any kind of suggestions are highly appreciable. Follow the comment section to give them.

ISI-ISO Reference Model:

This is the seven layer or level in a complete communication system. The lowest layer is physical layer and the highest one is known as the Application layer.

OSI Reference Model

OSI Model is a set of protocols that allows any two system to communication regardless of architecture. The purpose of OSI Model is to show how to communicate between different without requiring changes to the hardware and software. it is a model for understanding and designing framework for the design of network system that allow to communicate between all types of computer systems. It consists of Seven related layers, each of which defines part of the process of moving in formation across a network.

OSI Reference Model.

OSI Reference Model Diagram

The Open Systems Interconnect model has seven layers.

  1. Physical Layer
  2. Data Link Layer
  3. Network Layer
  4. Transport Layer
  5. Session Layer
  6. Presentation Layer
  7. Application Layer

Functions of above mentioned Different Layers of OSI Reference Model are given as follows:


  • Physical Layer is used to transmit bit over a medium to provide mechanical and electrical specification.
  • It provide the transfer medium such as cable
  • Used to define the voltage and data rates need to complete the process of transmission.
  • This layer is used to convert digital bits into required electrical signals.


  • The main function of data link layer is synchronization and error control for the information which are required to transmit over the physical layer.
  • It is used to organise bits into frames in order to provide hop to hop delivery.
  • Construct data frames using appropriate format as per accordance of given network.
  • Examine device address and acknowledge receipt of the frame.


  • To move the packet of data from source to destination in order to provide inter networking.
  • Route the signals through various channels tot he other end for the resequencing of packet transmission when needed.
  • Determine the network path on which to route the given packet.


  • The work of Transport layer is to ensure that data is sent and received in the same order.
  • Ensure reliability of packet transmission from node to node.
  • It monitors the packet transmission errors and resent the damaged form of packets.


  • Session layer initiates the communication link for the transmission.
  • It controls logging on and off, user identification, billing and along with this the session management.
  • Determine which node transmits any point at that time.


  • Presentation Layer performs the function of data encryption.
  • Perform the function of Data compression.
  • Transmission data to a format the receiving node understand.


  • Application layer allows access  to network resource present.
  • Enable sharing of remote drives and printers.
  • Provide files transfer services and file management services.

Follow the given links for OSI Model pdf

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