Similarities and Differences between OSI and TCP/IP model

This tutorial explains similarities and differences between OSI reference model and TCP/IP model in detail. Besides this, it also explains the differences between the original TCP/IP model and the updated TCP/IP model.

OSI Model vs TCP/IP Model (which one is better and why TCP/IP is used instead of the OSI)

Both TCP/IP and OSI are networking reference models. Development of both models was started in early 1970s. Both were published in 1980s. Manufacturers added support for one or both in their devices in 1990s. By the end of 1990s, TCP/IP model became common choice and OSI model rejected due to slower formal standardization process in comparison of TCP/IP model. Leading manufacturers discarded their proprietary networking models in favor of TCP/IP model in 2000s. Nowadays the world of computer networking uses only one networking model and that is the TCP/IP model.

Why OSI model is still taught in networking courses?

In terms of explanation and documentation, TCP/IP model stands nowhere near the OSI model. OSI model is one of the best explained and well-documented models ever created in computer networking world. It describes complex networking concepts, protocols and terms in such a manner that is not only easy to understand but also easier to remember.

Since both TCP/IP and OSI model were created to achieve the same goal, they both use the same set of open standard protocols and describe the networking concepts in similar manner. By learning one model, you can easily learn the other model.

For this reason, even OSI model is no longer supported and used by hardware manufacturers, still it is taught in almost all networking courses. Once students learned the OSI model, they are introduced with the TCP/IP model. Since they have been already learned the foundation topics and layered approach from OSI model, learning TCP/IP model becomes much easier for them.

This article also follows the same approach. First two parts of this article explains OSI model and its layers in detail. This part explains differences and similarities between TCP/IP model and OSI model and next parts explain TCP/IP model and its layers. Other parts of this article are following.

OSI Model Advantages and Basic Purpose Explained

This tutorial is the first part of the article. It briefly explains the reasons why OSI model was created along with the advantages.

OSI Seven Layers Model Explained with Examples

This tutorial is the second part of the article. It explains the seven layers of OSI model in details.

TCP/IP Reference Model Explained

This tutorial is the fourth part of the article. It explains the five layers of TCP/IP model in detail.

Data Encapsulation and De-encapsulation Explained

This tutorial is the fifth part of the article. It explains how data is encapsulated and de-encapsulated when it passes through the layers.

Similarities between TCP/IP model and OSI model

  • Both are the logical models.
  • Both define standards for networking.
  • Both provide a framework for creating and implementing networking standards and devices.
  • Both divide the network communication process in layers.
  • In both models, a single layer defines a particular functionality and set standards for that functionality only.
  • Both models allow a manufacturer to make devices and network components that can coexist and work with the devices and components made by other manufacturers.
  • Both models simplify troubleshooting process by dividing complex functions into simpler components.
  • Instead of defining the already defined standards and protocols, both models referenced them. For example, the Ethernet standards were already defined by IEEE before creation of these models. So instead of defining them again both models used them as IEEE Ethernet standards.

Differences between OSI model and TCP/IP model

  • OSI Layer model has seven layers while TCP/IP model has four layers.
  • OSI Layer model is no longer used while TCP/IP is still used in computer networking.
  • To define the functionality of upper layers, OSI uses three separate layers (application, presentation and session) while TCP/IP uses a single layer (application).
  • Just like upper layers, OSI uses two separate layers (Physical and Data link) to define the functionality of bottom layers while TCP/IP uses a single layer (Link) for the same.
  • To define the routing protocols and standards, OSI uses Network layer while TCP/IP uses Internet layer.
  • In comparison of TCP/IP model, OSI model is well documented and explains standards and protocols in more details.

Differences between TCP/IP original model and TCP/IP updated model

The TCP/IP model which we use nowadays is slightly different from the original TCP/IP model. The original TCP/IP model has four layers while the updated TCP/IP model has five layers.

The original version uses a single layer (Link layer) to define the functionality and components which are responsible for data transmission. The update version uses two layers (Data Link and Physical) for this.

The updated version divides the original Link layer based on the functionality. The functionality which is directly related to the physical transmission and the functionality which is indirectly related to the physical transmission are specified in Physical layer and in Data Link layer respectively.

In updated version, the name of Internet layer is changed to the Network layer.

Following figure compares OSI Reference model with both TCP/IP original and TCP/IP updated models.

compare tcp/ip model and osi model

No matter which model you study or learn first, once you learned one you can easily correlate it with other. In general comparison updated TCP/IP model is much or less similar to the OSI model except the application layer. For the purpose of learning, you can think application layer of TCP/IP does what top three layers (application, presentation and session) do in OSI model.

That’s all for this part. In next part of this article, I will explain TCP/IP model and its layers in detail. If you like this tutorial, please don’t forget to share it with friends through your favorite social site.

ComputerNetworkingNotes CCNA Study Guide Similarities and Differences between OSI and TCP/IP model