Session, Presentation, and Application Layers

Recall that there are two popular network models in use: the OSI Reference Model and the TCP/IP Reference Model. In this chapter you’ll learn about the top three layers of the OSI model. Those three OSI layers correspond to the Application Layer (top layer) in the TCP/IP model. FIGURE 6-1 shows how the layers in each model (OSI and TCP/IP) relate to one another.

An illustration presents the layers in the O S I and T C P or I P reference models. O S I model has seven layers, and T C P or I P has four layers. In the O S I model, the data link layer and physical are separate layers. In T C P, physical and data link are both combined as a single network layer. The internet and transport are the third and fourth layers in both the models. Session and presentation layers are a part of the O S I model. There are no session and presentation layers in the T C P model. The final layer in both the models is the application layer.

FIGURE 6-1 OSI model compared to the TCP/IP model.

The fact that the TCP/IP model groups these layers together should tell you something. Although each layer has its own responsibilities, they are closely related. The functions you’ll ...

Get Fundamentals of Communications and Networking, 3rd Edition now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.

Start your free trial