Difference Between OSI and TCP-IP Model

Last Updated : May 10, 2022

In this blog, we will compare the OSI model with TCP/IP model and understand the difference between OSI and TCP-IP Model. Still, before moving to the differences, we need to understand both these models and their layers.

So, let's start with the OSI model of computer networking.

OSI Model of Computer Networking

OSI stands for Open System Interconnection. The OSI Model was developed by (ISO) International Standard organization to help standardize communication between computers.

The original objective behind the OSI model of computer networking was to make communication possible between two different vendors. Because, when the internet was growing at the beginning of the time, different vendors could not communicate with each other and, OSI Model came as the standard model for discussing, teaching, and learning the networking procedures in the field of Information technology.

So, the OSI model was developed, but it was never implemented and remained as just a reference model for study purposes only.

There are 7 layers in OSI Model. Let’s understand the OSI Model layers.

The OSI Model Layers

The 7 OSI model layers are as follows:


Layer Name	PDU (Protocol Data Unit)
Application Layer	Data
Presentation Layer	Data
Session Layer	Data
Transport Layer	Segmentation
Network Layer	Packet
Data Link Layer	Frame
Physical Layer	Signals, Bits

Let's get into more details about each and every layer.

Application Layer

This layer offers network services to end-user applications and provides interfacing of data.

In this layer, the user interacts with application software like google chrome and Mozilla Firefox & Edge.

As for web browsing, we use HTTP & HTTPs. For file sharing, we use FTP.

Presentation Layer

The name itself represents that this layer presents the data from the application layer and marks it with a formatting code.

Like it marks the text file as .txt, audio file as .mp3 and many more extensions, so the machine can identify what is the file actually we are sending or receiving.

Session Layer

This layer actually deals with the connection.

The major functions of this layer are:

Establish Connection
Manage the Connection
Session Restore – restores the connection

Transport Layer –

This layer is an intermediate layer between the upper layers and lower layers.

It delivers and receives the data across the network from source to destination.

Major functions of the transport layer are –

Segmentation
Connection Management

Segmentation – The process of breaking the large data files into smaller files that the network can accommodate. (According to the bandwidth of the user)

The Transport layer uses the two protocols for connection management.


TCP	UDP
Connection oriented	Connection less
TCP is reliable	UDP is not reliable
3-way handshake process	No handshake
Also guarantees ordering of messages.	Do not guarantee ordering of messages.
Heavy-weight protocol	Light-weight protocol
Flow control	No flow control
Slow protocol because of responsibilities.	Fast protocol because of no responsibilities.
HTTP, TELNET, FTP, ETC	DHCP, DNS, SNMP, ETC

You can also check out our blog - UDP vs TCP, for a better understanding of these two.

Network Layer –

The Network layer is responsible for providing IP addresses.

Router and Multi-layer switches work on this layer.

The Main functions of the network layer are Addressing, Routing & forwarding.

Data is known as packet in the network layer.

Data-Link Layer –

This layer encodes and decodes data packets into bits using its transmission protocol.

Framing is also done on this layer.

Framing means when the packet comes from the network layer into data link, it converts the packet into frames and sends it to the physical layer.

Data-link layer is divided into two sublayers- MAC (Media Access Control) & LLC (Logical Link Control)

Physical Layer –

This layer is responsible for connecting the device to physical connections like HUB and Repeaters.

Electric voltage, radio frequency or pulses are the medium through which the data is transmitted.

Cables and connectors are being used here in this layer.

Summary of OSI Model


Layers	Encapsulation Process & PDU
Application Layer	DATA
Presentation Layer	DATA
Session Layer	DATA
Transport Layer	Segments (Identification of TCP/UDP + Upper Data)
Network Layer	Packet (SRC/DST IP + TCP/UDP + Upper Data)
Data-Link Layer	Frame (SRC/DST IP + SRC/DST MAC+ TCP/UDP + Upper Data)
Physical Layer	The whole process is decapsulated

These are seven of the OSI Model Layers. Let’s move to the TCP/IP Model.

TCP/IP Model in Computer Network

The TCP/IP Model in Computer Network was designed by the Department of Defense (DOD), and it is based on standard protocols.

The TCP/IP model is also known as IP Stack, and this model is practically being implemented. This model is a widely adopted model due to its simplicity, and it is also known as the concise version of OSI model.

TCP Layers:

As compared to OSI Model, there are 4 TCP layers which are:

Functions of TCP Layers –

Application, Presentation & Session – SMTP, TELNET, FTP, TFTP, DNS, SNMP, ETC
Transport Layer – TCP/UDP
Internet Layer – ARP, IP, IGMP, ICMP
Network Access Layer – Bits & Signals

So, there are 7 layers in the OSI Model whereas in TCP/IP, we only have 4 layers, and the working is same as discussed in OSI model.