Understanding the OSI Model in Networking

Oct 19, 2024

OSI Model Overview

Introduction

  • Topic: Open System Interconnection (OSI) Model
  • Purpose: Understand network communication and data transfer between computers.
  • Importance: Essential for those studying or working in networking.

What is the OSI Model?

  • A reference model for how applications communicate over a network.
  • Developed in 1976 by the International Organization for Standardization (ISO).
  • Facilitates interoperability among different hardware and software.

Purpose of the OSI Model

  • Guides technology vendors and developers.
  • Defines a common framework for hardware and software communication.

OSI Model Layers

  • Total of seven layers:
    1. Application Layer
    2. Presentation Layer
    3. Session Layer
    4. Transport Layer
    5. Network Layer
    6. Data Link Layer
    7. Physical Layer
  • Mnemonic for remembering the order: All People Seems To Need Data Processing

Layer Functionality

  • Each layer has specific functions and protocols.
  • Interaction between layers is crucial for data transfer.

Top Layers (Software Layers)

  1. Application Layer
    • User interaction with applications (e.g., Google Chrome, email clients).
  2. Presentation Layer
    • Translates data into machine-readable format (binary).
    • Functions: Data translation, encryption, and decryption.
  3. Session Layer
    • Establishes and maintains session connections between sender and receiver.
    • Ensures data is received without loss.

Bottom Layers (Hardware Layers)

  1. Transport Layer
    • Divides data into smaller segments.
    • Controls data flow and error management.
    • Protocols: TCP (connection-oriented) and UDP (connectionless).
  2. Network Layer
    • Handles logical addressing and routing (IP addressing).
    • Data unit is referred to as a packet.
  3. Data Link Layer
    • Responsible for physical addressing (MAC addresses).
    • Allows access to the physical media for data frames.
  4. Physical Layer
    • Transmits raw bits over the physical medium.
    • Converts binary data into signals (electrical or optical).

Example Story to Understand OSI Model

  • Abdul (CEO) = Application Layer
    • Sends data (400 pages) to Pintu.
  • Pintu = Presentation Layer
    • Translates data into an understandable format (Arabic to English).
  • Saqib = Session Layer
    • Establishes connection and ensures data transfer is acknowledged.
  • Tuba = Transport Layer
    • Segments data into smaller sets (100 pages each).
  • Noor = Network Layer
    • Adds addressing and routing information to segments.
  • Danish = Data Link Layer
    • Adds MAC addressing to frames and ensures integrity.
  • Peter = Physical Layer
    • Sends data through the physical medium.

Summary

  • Each layer has a specific role in the data transfer process.
  • The model facilitates communication between different systems.
  • Understanding the OSI model is crucial for networking professionals.

Conclusion

  • Further exploration of each OSI layer will be provided in future videos.
  • Importance of the OSI model in network communication emphasized.
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