TCP IP Model

The top layer of both models is called the Application Layer,however, in the case of the TCP/IP model, the Application Layer not only does the job of Application Layer, but also the Presentation Layer and a significant portion of the Session Layer of the OSI model. The second layer of the TCP/IP model is the Transport Layer. This is the same name as the Transport Layer in the OSI model. However, significantly, in the TCP/IP model, the Transport Layer does the function of the Transport Layer in the OSI model, as well as some of the functions of the Session Layer.

Next in the TCP/IP model, we have the Internet Layer. The Internet Layer actually covers the job of the Network Layer in the OSI model, as well as the upper portion of the Data Link Layer in the OSI model. Finally, the last layer of the TCP/IP model is the Network Interface Layer. When we compare the Network Interface Layer to the Physical Layer of the OSI model,we see that the Network Interface Layer does the job of the Physical Layer and the lower half of the Data Link Layer of the OSI model.