The TCP/IP model is a framework that is used to model the communication
in a network. It is mainly a collection of network protocols and organization of
these protocols in different layers for modeling the network.
It has four layers, Application, Transport, Network/Internet and Network
Access.
While the OSI model has seven layers, the 4 layer TCP/IP model is simpler
and commonly used in today’s Internet and networking systems.
Role of TCP/IP
One of its main goals is to make sure that the data sent by the sender arrives
safely and correctly at the receiver’s end. To do this, the data is broken down
into smaller parts called packets before being sent. These packets travel
separately and are reassembled in the correct order when they reach the
destination. This helps prevent errors and makes sure the message is
complete and accurate.
TCP
Layers of TCP/IP Model
1. Application Layer
The Application Layer is the top layer of the TCP/IP model and the
one closest to the user. This is where all the apps you use like web
browsers, email clients, or file sharing tools connect to the network. It acts
like a bridge between your software (like Chrome, Gmail, or WhatsApp) and
the lower layers of the network that actually send and receive data.
It supports different protocols like HTTP (for websites), FTP (for file
transfers), SMTP (for emails), and DNS (for finding website addresses). It
also manages things like data formatting, so both sender and receiver
understand the data, encryption to keep data safe, and session
management to keep track of ongoing connections.
2. Transport Layer
The Transport Layer is responsible for making sure that data is sent reliably
and in the correct order between devices. It checks that the data you send
like a message, file, or video arrives safely and completely. This layer uses
two main protocols: TCP and UDP, depending on whether the
communication needs to be reliable or faster.
TCP is used when data must be correct and complete, like when loading a
web page or downloading a file. It checks for errors, resends missing pieces,
and keeps everything in order. On the other hand, UDP (User Datagram
Protocol) is faster but doesn’t guarantee delivery useful for things like live
video or online games where speed matters more than perfect accuracy.
3. Internet Layer
The Internet Layer is used for finding the best path for data to travel across
different networks so it can reach the right destination. It works like a traffic
controller, helping data packets move from one network to another until they
reach the correct device. This layer uses the Internet Protocol (IP) to give
every device a unique IP address, which helps identify where data should
go.
The main job of this layer is routing deciding the best way for data to travel. It
also takes care of packet forwarding (moving data from one point to
another), fragmentation (breaking large data into smaller parts),
and addressing.
4. Network Access Layer
The Network Access Layer is the bottom layer of the TCP/IP model. It deals
with the actual physical connection between devices on the same local
network like computers connected by cables or communicating through Wi-
Fi. This layer makes sure that data can travel over the hardware, such as
wires, switches, or wireless signals.
It also handles important tasks like using MAC addresses to identify devices,
creating frames (the format used to send data over the physical link), and
checking for basic errors during transmission.
Working of TCP/IP Model
The working of TCP/IP can be explained with the help of the diagram given
below and explained :
TCP/IP WORKING MODEL
When Sending Data (From Sender to Receiver)
Application Layer: Prepares user data using protocols like HTTP, FTP,
or SMTP.
Transport Layer (TCP/UDP): Breaks data into segments and ensures
reliable (TCP) or fast (UDP) delivery.
Internet Layer (IP): Adds IP addresses and decides the best route for
each packet.
Link Layer (Network Access Layer): Converts packets into frames and
sends them over the physical network.
When Receiving Data (At the Destination)
Link Layer: Receives bits from the network and rebuilds frames to pass
to the next layer.
Internet Layer: Checks the IP address, removes the IP header, and
forwards data to the Transport Layer.
Transport Layer: Reassembles segments, checks for errors, and
ensures data is complete.
Application Layer: Delivers the final data to the correct application (e.g.,
displays a web page in the browser).
Why TCP/IP is Used Over the OSI Model
TCP/IP is used over the OSI model because it is simpler, practical, and
widely adopted for real-world networking and the internet. The diagram
below shows the comparison of OSI layer with the TCP :
OSI
