Seven layers OSI model

​Seven layer OSI model consists of the following components. I will just list these layers here, later I will be explaining details of each one.

1. Physical 

2. Datalink

3. Network 

4. Transport 

5. Session

6. Presentation

7. Application

Please be aware that these layers are theoretical and implementation of them is different. For example TCP protocol that is widely used, only consists of 4 layers.

How does this model of 7 layers fits 4 layers of TCP protocol?

A single TCP protocol layer may include more than one OSI model layer.

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