The TCP/IP layering model is a 4 layer model, with the layers named as Application, Transport, Internet and Host-to-Network. The diagram given below illustrates the layering in the TCP/IP model.
The TCP/IP layering model
While the OSI 7 layering model was developed as a theoritical model, the TCP/IP layering model was developed more from the actual experience of creating the TCP and IP protocol suites. Infact, the TCP/IP model was conceptualized by the forum that developed and standardized the TCP/IP protocol suite.
In the TCP/IP layering model,
- The logical functionalities inside the Application, Presentation and Session (top 3 layers) layers of the OSI model have been clubbed onto a single layer named as Application layer.
- The Transport layer and its logical functionalities remain the same as that of the Transport layer in the OSI layering model, which is end-to-end communcation, application multiplexing/demultiplexing, reliability, flow control and congestion control.
- The Internet layer is same as the Network layer in the OSI model and its functionality is end-to-end routing of packets.
- The “Host-to-Network” layer is responsible for hop-to-hop data transmission/reception and it combines the roles of the datalink and the physical layer of the OSI model.