OSI 7 Layer

The OSI Model introduces two more layers, presentation and session layer.

layer 5: session layer

• Session layer: Responsible for facilitating the communication between actual applications and the transport layer
• Takes application layer data and hands it off to the presentation layer
• It’s the part of the operating system that takes the application layer data that’s been unencapsulated from all the layer below it and hands it off to the next layer in the OSI model

layer 6: Presentation Layer

• Presentation Layer: Responsible for making sure that the unencapsulated application layer data is able to be understood by the application in question
• This is the part of an operating system that might handle encryption or compression of data.

While these are important concepts to keep in mind, you’ll notice that there isn’t any encapsulation going on. That’s why in our mode, we lump all of these functions into the application layer. We believe a five layer model is the most useful when it comes to the day-to-day business of understanding networking, but the seven-layer OSI model is also prevalent.

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