How Data Flows Through Networking Layers – Real-Life Example

 

Data Flow in Networking Explained for Beginners – All Layers with Step-by-Step Example

In today’s digital world, we use multiple online platforms for communication, sharing information, sending messages, emails, images, videos, and many other things. But have you ever thought about how this data travels from your device to another person's device?

Data is sent from the sender to the receiver through different layers of the networking model. These layers are called the OSI model layers (Open System Interconnection) model. Each layer performs specific tasks and works together to make communication possible.

In this blog, we will deeply understand how data flows through networking layers using a real-life example, and also understand the concept of encapsulation and Decapsulation.

What is Data Flow in Networking?

The complete process of data travel from the sender device to the receiver device is known as Data flow.

A user sends a message to someone, first the message travels through all the layers, then travels through the internet, and finally, the message reaches the receiver device, passing through the same layer but in the opposite order.

This step-by-step process of data is called data flow.

Now we understand all this process through the OSI model in a structured way.

The Seven Layers of the OSI Model

All the layers of the OSI model:

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

These layers work together to successfully send and receive data.

The sender side starts from Top to bottom (Application Layer to Physical Layer) which is called encapsulation.

The receiver side starts from Bottom to top (Physical Layer to Application Layer), which is called Decapsulation.

You can also understand the difference between the OSI Layers and TCP/IP layers.

Encapsulation and Decapsulation Explained

Encapsulation

Encapsulation is the sender side, in which data travels from the Application Layer to the Physical Layer.

The data gets packed layer by layer before transmission, which means every layer adds extra information to the original data. This extra information is like (data, header, header, header, and trailer).

This information helps layers to send data to the correct destination.

All of these processes are called encapsulation.

Decapsulation

Decapsulation is the receiver side, which is a reverse process.

When data finally reaches the destination address, it starts moving from the physical layer to the application layer, which means the layer starts removing extra information from the data, and passing through all the layers, the original data finally reaches the user.

All these reverse journey of data is called Decapsulation.

You must have to learn about Networking basics before understanding data flow.

Real-life Example Layer by layer

Let’s understand the data flow with a real-life example.

(A user sends a “Hello” message to someone).

It looks like a simple message, but behind the scenes, this message travels through all the layers and then reaches the destination.

Now, let’s understand the process.

Application layer (layer 7)

Communication starts in this layer; the user types a “Hello” message and presses send.

In this layer, users interact with the application.

Presentation Layer (layer 6)

This layer starts preparing the message, converts the message into a proper format, and applies encryption so the message becomes secure.

In this layer, data becomes readable and protected.

Session Layer (layer 5)

This layer manages the communication session between the user’s phone and the server and keeps the session active while the message is being sent.

In this layer, connections are created and managed.

Transport Layer (layer 4)

This layer breaks the message into small parts, which are called segments. It also makes sure the message is sent correctly or in the right order and ensures all the parts are sent.

If something is lost or not in the right sequence, the transport layer resends.

Network Layer (layer 3)

This layer adds the IP address of the sender or receiver, so that the network can find the correct path and send the message to the right person.

Data Link Layer (layer 2)

This layer is used for adding the MAC address, which helps devices to communicate within the same local network.

It also checks the transmission errors.

Physical Layer (layer 1)

This layer converts the message into signals. Wi-Fi signal or electrical signals.

Now those signals travel through the internet and reach the receiver.

Receiver side process

Once the message is received by the right person, the reverse Process starts.

Now the message moves upward from the physical layer to the application layer.

Each layer removes its header and information that was added on the sender side, and makes the data go back to its original form.

Finally, the Receiver read the message “Hello”.

Different Networking devices, such as routers, switches, hub helps data to travel from the sender to the receiver.

Interview questions to remember

Define Data flow in networking?

Answer:
The complete process of data travel from the sender device to the receiver device is known as Data flow.

What is the use of the transport layer?

Answer:
This layer breaks the message into small parts, which are called segments. It also makes sure the message is sent correctly or in the right order, and ensures all the parts are sent

Explain the OSI model?

Answer:
The OSI model stands for (Open System Interconnection). It is just a framework that tells how data communications work in networking.

Name all the layers of the OSI model?

Answer:

Here are all the layers of the OSI model:

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

Define Encapsulation?

Answer:
Encapsulation is the sender side, in which data travels from the Application Layer to the Physical Layer.

Define Decapsulation?

Answer:
Decapsulation is the receiver side, which is a reverse process. The reverse journey of data is called Decapsulation.

What are headers in encapsulation?

Answer:

Headers have information about data such as address, destination address, errors, sequence, and other details.

Differentiate between encapsulation and Decapsulation?

Answer:
The sender side starts from Top to bottom (Application Layer to Physical Layer), which is called encapsulation.

The receiver side starts from Bottom to top (Physical Layer to Application Layer), which is called Decapsulation.

Which one is the user interaction layer?

Answer:
The application layer is the user interaction layer, in this layer, the user interacts with the application.

What does encryption at the presentation layer do?

Answer:
The Presentation layer applies encryption to the message, which protects the data and makes it more secure.

Define the session layer?

Answer:
This session layer manages the communication session between the user’s phone and the server and keeps the session active while the message is being sent.

Define segments in the transport layer?

Answer:
This layer breaks the message into small parts, which are called segments, and it also makes sure the message is sent correctly or in the right order.

Define the network layer.

Answer:

The network layer is a logical addressing and routing layer which assign IP address for both the sender and the receiver.

Define the physical layer?

Answer:
This layer converts the message into signals. Wi-Fi signal or electrical signals. Those signals travel through the internet and reach the receiver.

Conclusion

Every message we send follows a complete and organized process through networking layers. Whenever a user sends a simple message, it can be a photo, video, or email, and when browsing a website, the same process of data flow is running in the background. 

OSI model helps us to understand the concept of how data (messages) travel over the Internet. All these layers of the OSI model perform specific tasks and play an essential role in successful data transmission.

In conclusion, Understanding of data flows through networking layers is very important for students. It is also the most common topic of exams. Once you clearly understand the journey of data through the OSI model, many types of networking concepts become easy or simple.