How does Network work?

This is a simple, diagrammatic way to represent how a network works.

Let’s assume that A and B are a couple. A is in London, and B is in India. They want to communicate with each other. To do so, they’ve decided to use an application called WhatsApp.

Now, using the power of modern networking technology, they can establish a connection and make a video call. But how does this actually work?

Before diving into the technical details, let’s break this down into some simple concepts. First, A and B have chosen WhatsApp as their communication application. After installing the app, they start their video call. But what’s going on behind the scenes during this process?

When A and B start their call, data is being transferred between them. This data travels over the internet, which is essentially a vast network of servers, cables, and devices connected worldwide. These connections can include fiber optic cables that run under the oceans, linking different countries together. This infrastructure allows data to travel between A in London and B in India almost instantly, enabling them to see and hear each other clearly during their video call.

At this point, they have created a network—using the internet as a medium—to communicate. And that network relies on a lot of technical processes happening behind the scenes, including the transmission of data packets across long distances and through various network devices.

Now understand how actually network works :-

Understanding how a network works is essential to grasp how devices communicate with each other. Networks work in two ways: the theoretical approach (OSI model) and the practical approach (TCP/IP model). Let’s explore both

a) Theoretical Approach: OSI Model

The OSI (Open Systems Interconnection) model is a conceptual framework that explains how data travels through a network in seven distinct layers. Each layer has a specific role in the process of data transmission.

The 7 Layers of the OSI Model (Top to Bottom):

1. Application Layer:

   • Interface between the user and the network.

   • Examples: Browsers (HTTP), file transfers (FTP).

2. Presentation Layer:

   • Ensures data is in a readable format. Handles encryption and compression.

   • Example: Translating image files (.jpg to readable data).

3. Session Layer:

   • Establishes, manages, and terminates communication sessions between devices.

   • Example: Video calls.

4. Transport Layer:

   • Ensures reliable data transfer. Manages segmentation, error detection, and flow control.

   • Protocols: TCP, UDP.

5. Network Layer:

   • Handles routing and addressing. Determines the best path for data to travel.

   • Protocol: IP.

6. Data Link Layer:

   • Transfers data between devices on the same network. Handles MAC addressing.

   • Example: Switch communication.

7. Physical Layer:

   • Handles raw data transmission over cables, Wi-Fi, or other mediums.

   • Example: Ethernet cables, Wi-Fi signals.

Everyday Example:
When you browse a website:

• The Application Layer sends your request.

• The Transport Layer ensures it’s error-free.

• The Network Layer routes it to the destination server.

• The process reverses for the server’s response.

b) Practical Approach: TCP/IP Model

The TCP/IP (Transmission Control Protocol/Internet Protocol) model is the practical implementation of networking. It simplifies the OSI model into four layers:

The 4 Layers of the TCP/IP Model (Top to Bottom):

1. Application Layer:
   Combines the OSI model’s Application, Presentation, and Session layers.

   • Examples: HTTP, FTP, DNS.

2. Transport Layer:
   Manages communication reliability using TCP (connection-oriented) or UDP (connectionless).

3. Internet Layer:
   Routes data between networks using IP addresses.

   • Protocols: IP, ICMP.

4. Network Access Layer:
   Combines the OSI’s Data Link and Physical layers, ensuring data is transmitted over the hardware.

Key Differences Between OSI and TCP/IP Models:

• OSI: Theoretical and detailed, focusing on standardization.

• TCP/IP: Practical, widely used in real-world networking.