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.
Computer network models facilitate establishing a connection between the sender and receiver and smoothly transmitting the data. There are two most popular computer network models: OSI Model and TCP/IP (Transport Control Protocol/Internet Protocol) Model. While OSI is a reference model that describes the functions of a networking system, TCP/IP is the communication protocol suite to connect network devices to the Internet. In this article, we will understand these two models in detail. We will learn about their layers and the difference between OSI vs TCP/IP Model.
Table of Contents
- What is OSI Model?
- What is TCP/IP Model?
- Similarities between the TCP/IP and OSI models
- Difference between OSI Model vs TCP/IP Model
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:
|OSI stands for Open Systems Interconnection.
|TCP/IP stands for Transmission Control Protocol/Internet Protocol
|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:
2. Data Link
|It has four layers:
1. Network Access
|It is less reliable.
|TCP/IP is more reliable.
|Protocols are easy to replace.
|Protocols are not easy to replace.
|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.
|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.
|In the OSI model, the network layer provides connection-oriented and connectionless services.
|In this model, the network layer provides only connectionless service.
|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.
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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Why do we use TCP/IP model over the OSI model?
OSI is a theoretical model. This model does not take into consideration the availability of appropriate technology. It lays out the guidelines on how communication needs to be done and lacks practical implementation. On the other hand, TCP/IP provides standards on which the Internet was developed. It is a more practical model.
What is the key difference between TCP/IP and OSI Model?
The key difference between OSI and TCP/IP Model is that OSI is a conceptual framework while TCP/IP is a communication protocols suite. The OSI model offers seven layers with different functions that the TCP/IP model groups into four layers.
Which model is superior, OSI or TCP/IP?
The OSI model should be preferred over the TCP/IP model when it comes to proper documentation, specification, and modularization. However, if the network's implementation, reliability, and security are more critical, the TCP/IP model should be preferred over the OSI model.
What layers exist in the OSI model but not in the TCP model?
The OSI layers are as follows: application layer, presentation layer, session layer, transport layer, network layer, the data-link layer, and physical layer. The presentation layer is missing from the TCP/IP model but is in the OSI model.