OSI vs TCP/IP Model: What’s the Difference?

Take a brief look at the similarities and differences between the two most popular computer network models: the OSI model and the TCP/IP model.

Table of Contents

• What is OSI Model?
  • Layers of OSI Model
• What is TCP/IP Model?
  • Layers of TCP/IP Model
• Similarities between the TCP/IP and OSI models
• Difference between OSI Model vs TCP/IP Model
• Conclusion

What is OSI Model?

Developed by ISO (International Organization for Standardization) in 1984, OSI is a conceptual model that defines network communication. It consists of 7 layers where each layer performs a specific function.

For more information, you can also explore: OSI Model Explained: 7 Layers and Their Functions

The OSI model has the following layers:

• Physical Layer: It is the lowest layer of the OSI model that is responsible for the physical data connection between the devices.
• Data Link. It ensures error-free node-to-node delivery of the message.
• Network Layer: The data gets its address in this layer. It also received routing instructions from moving from source to destination in the network.
• Transport Layer: It is responsible for reliable message delivery across different points on the network on its way to its destination.
• Session Layer: This layer helps with establishing, managing, and terminating sessions.
• Presentation Layer: It is responsible for encrypting and decrypting the data and converting it into a form that is accessible by the application layer.
• Application Layer: In this layer, an application (for example, an internet browser) receives the data and a user can then interact with it.

What is TCP/IP Model?

The TCP/IP (Transmission Control Protocol/Internet Protocol) model was introduced before the OSI model. This model helps users understand how a specific computer should be connected to the internet and how data can transmit between them. TCP/IP is used more compared to the OSI model for providing communication between computers over the internet.

The following are the four layers of the TCP/IP model:

• Network Access Layer: It is the lowest layer of the TCP/IP Model that helps in the transmission of data between two devices on the same network. This layer is a combination of the Physical and Data Link layer of the OSI model.
• Internet Layer: Helps in moving packets from destination to source. This layer corresponds to the Network layer of the OSI Model.
• Transport Layer: Responsible for reliable and error-free process to process message delivery. It is parallel to the Network layer of the OSI Model.
• Application Layer: This layer provides access to network resources. When the Application, Presentation, and Sessions layers of the OSI model are combined, they perform similar functions as the Application layer of the TCP/IP model.

Also Read: Networking Basics – A Beginner’s Guide

Similarities between the TCP/IP and OSI models

• Both the models are based upon layered architecture.
• Protocols are defined in a layer-wise way.
• Both models convert the raw data into packets and help them reach their destination node.
• Each model has different layers with a specific function. This helps in identifying issues if any failure occurs.
• The Physical and Data Link layers of the OSI model correspond to the Network Access layer of the TCP/IP model.
• The Application, Presentation, and Sessions layers of the OSI model correspond to the Application layer of the TCP/IP model.
• Both models have the network layer and the transport layer.

Also Read: Difference Between LAN and WAN

Difference between OSI Model and TCP/IP Model

The following are the differences between OSI Model vs TCP/IP Model:

Parameter	OSI Model	TCP/IP Model
Full form	OSI stands for Open Systems Interconnection.	TCP/IP stands for Transmission Control Protocol/Internet Protocol
Definition	It is a generic, protocol independent standard that serves as a communication gateway between the network and the end-user.	This is a protocol-dependent model that allows the connection of hosts over a network.
Number of layers	It has seven layers: 1. Physical 2. Data Link 3. Network 4. Transport 5. Session 6. Presentation 7. Application	It has four layers: 1. Network Access 2. Internet 3. Transport 4. Application
Reliability	It is less reliable.	TCP/IP is more reliable.
Protocol replacement	Protocols are easy to replace.	Protocols are not easy to replace.
Function	It offers standardization to different hardware devices, such as routers and switches.	It provides a connection between various computers but does not provide standardization to hardware devices.
Approach type	Follows a vertical approach.	Follows a horizontal approach.
Data link and physical layer	The data link layer and physical are separate.	The data link and physical layers are combined as a single host-to-network layer.
Service type	In the OSI model, the network layer provides connection-oriented and connectionless services.	In this model, the network layer provides only connectionless service.
Assurance	The transport layer provides a guarantee for the delivery of packets.	The transport layer in this model does not provide assurance delivery of packets.
Session and presentation layer	The session and presentation layers are separate.	The session and presentation layers are not segregated and are included in the application layer.
Minimum header size	The minimum header size is 5 bytes.	The minimum header size is 20 bytes.

Conclusion

In this blog, we have covered the difference between TCP/IP and OSI Model. OSI is a generic model and is based on the functions of each layer. On the other hand, TCP/IP is a protocol-oriented model. To learn more about the OSI model, read our post – OSI Model Explained: 7 Layers and Their Functions.

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