2 min to read

Understanding OSI 7 Layers and TCP/IP 4 Layers

A comprehensive comparison of OSI and TCP/IP network models

Featured image


🎯 Overview

Let’s explore the OSI 7 Layer model and TCP/IP 4 Layer model, understanding their structures and differences.

🌐 OSI 7 Layers

📝 What is OSI?

The OSI (Open Systems Interconnection) model is a reference model for network protocol stacks developed by ISO (International Organization for Standardization).

🔍 Layer Structure

🔶 OSI Model (7 Layers):

  1. Application (🔗): Interfaces with the user and provides network services (HTTP, FTP).
  2. Presentation (🎨): Formats and encrypts data for the application layer.
  3. Session (🗂️): Manages sessions and connections between devices.
  4. Transport (📤): Ensures reliable data transfer (TCP, UDP).
  5. Network (🌍): Handles logical addressing and routing (IP).
  6. Data Link (🖧): Manages error detection and frame synchronization (Ethernet).
  7. Physical (⚡): Transmits raw data over physical media (cables, radio waves).

🌐 TCP/IP 4 Layers

📝 What is TCP/IP?

TCP/IP (Transmission Control Protocol/Internet Protocol) is the reference model for internet protocol stacks.

🔍 Layer Structure

🔷 TCP/IP Model (4 Layers):

  1. Application (🔗): Combines Application, Presentation, and Session layers (HTTP, DNS).
  2. Transport (📤): Provides end-to-end communication (TCP, UDP).
  3. Internet (🌐): Handles addressing and routing (IP).
  4. Network Interface (🖧): Combines Data Link and Physical layers, managing hardware transmission.


🔄 Key Differences: OSI vs TCP/IP Model

🔑 Aspect 📶 OSI Model 🌐 TCP/IP Model
🧩 Layer Organization 7 distinct layers 4 consolidated layers
🛠️ Application Functionality Divided into Application, Presentation, Session Combined into a single Application layer
🔄 Data Flow Layer-by-layer processing Direct data transfer between layers
📏 Implementation Theoretical reference model Practical implementation standard


📊 OSI vs TCP/IP Model Comparison

📶 OSI Model 🌐 TCP/IP Model
🔗 Application 🔗 Application
🎨 Presentation
🗂️ Session
📤 Transport 📤 Transport
🌍 Network 🌐 Internet
🖧 Data Link 🖧 Network Interface
⚡ Physical

🔑 Key Points

  1. OSI model is more detailed but theoretical
  2. TCP/IP is more practical and widely implemented
  3. Both models serve as reference frameworks
  4. TCP/IP combines several OSI layers for efficiency


📚 Reference