Fundamentals of Networking
Protocol Layers :
Protocol layers divide network communication into multiple levels,
where each layer performs a specific function. Layered
approach makes networking simple, modular, and easy to
understand.
The OSI Model :
OSI Model explains how data travels from one computer to another over a network.
It has 7 layers. Each layer has one simple job. Think of it like sending a message on WhatsApp.
Layers of the OSI Model (Top to Bottom) :
1. Application Layer
The Application Layer is the layer that is
closest to the user .
It allows users to access network
services like browsing, emailing, and
chatting.
This layer does not transfer data itself ,
but it provides the interface to use the
network.
Real-life example:
When you type a message in WhatsApp,
the Application Layer allows you to use
the chat feature.
Diagram Of Application Layer
, 2. Presentation Layer
The Presentation Layer is
responsible for formatting the
data so that the sender and
receiver can understand it.
It also performs encryption for
security and decryption at the
receiver side .
This layer ensures that data remains .
safe and readable
Real-life example:
Your WhatsApp message is converted into a secure format before being sent.
3. Session Layer
The Session Layer manages the
connection between two
devices .
It establishes the session,
keeps it active during
communication, and terminates
it after completion.
This layer ensures that
communication happens in an
organized manner .
Real-life example:
While chatting on WhatsApp, the Session Layer keeps the conversation connected until you close the app.
4. Transport Layer
The Transport Layer ensures
reliable data delivery from sender
to receiver.
It breaks large data into smaller
segments and checks for errors or
data loss .
If any data is missing, this layer
requests retransmission.
Protocol Layers :
Protocol layers divide network communication into multiple levels,
where each layer performs a specific function. Layered
approach makes networking simple, modular, and easy to
understand.
The OSI Model :
OSI Model explains how data travels from one computer to another over a network.
It has 7 layers. Each layer has one simple job. Think of it like sending a message on WhatsApp.
Layers of the OSI Model (Top to Bottom) :
1. Application Layer
The Application Layer is the layer that is
closest to the user .
It allows users to access network
services like browsing, emailing, and
chatting.
This layer does not transfer data itself ,
but it provides the interface to use the
network.
Real-life example:
When you type a message in WhatsApp,
the Application Layer allows you to use
the chat feature.
Diagram Of Application Layer
, 2. Presentation Layer
The Presentation Layer is
responsible for formatting the
data so that the sender and
receiver can understand it.
It also performs encryption for
security and decryption at the
receiver side .
This layer ensures that data remains .
safe and readable
Real-life example:
Your WhatsApp message is converted into a secure format before being sent.
3. Session Layer
The Session Layer manages the
connection between two
devices .
It establishes the session,
keeps it active during
communication, and terminates
it after completion.
This layer ensures that
communication happens in an
organized manner .
Real-life example:
While chatting on WhatsApp, the Session Layer keeps the conversation connected until you close the app.
4. Transport Layer
The Transport Layer ensures
reliable data delivery from sender
to receiver.
It breaks large data into smaller
segments and checks for errors or
data loss .
If any data is missing, this layer
requests retransmission.
