Advantages and Disadvantages of the OSI Model

The advantages of the OSI model are

• It is a generic model and acts as a guidance tool to develop any network model.
• It is a layered model. Changes are one layer do not affect other layers, provided that the interfaces between the layers do not change drastically.
• It distinctly separates services, interfaces, and protocols. Hence, it is flexible in nature. Protocols in each layer can be replaced very conveniently depending upon the nature of the network.
• It supports both connection-oriented services and connectionless services.

The disadvantages of the OSI model are

• It is purely a theoretical model that does not consider the availability of appropriate technology. This restricts its practical implementation.
• The launching timing of this model was inappropriate. When OSI appeared, the TCP/IP protocols were already implemented. So, the companies were initially reluctant to use it.
• The OSI model is very complex. The initial implementation was cumbersome, slow and costly.
• Though there are many layers, some of the layers like the session layer and presentation layer have very little functionality when practically deployed.
• There is a duplication of services in various layers. Services like addressing, flow control and error control are offered by multiple layers.
• The standards of OSI model are theoretical and do not offer adequate solutions for practical network implementation.
• After being launched, the OSI model did not meet the practical needs as well as the TCP/IP model. So it was labeled as inferior quality.
• TCP/IP model was very much preferred by the academia. It was believed that OSI was a product of the European communities and the US government, who were trying to force an inferior model to researchers and programmers. Hence, there was considerable resistance in adopting it.