Describe the layers of TCP/IP model.

TCP/IP model has five layers-

(i) Physical layer

(ii) Network access layer

(iii) Internet layer

(iv) Host-to-host or, transport layer

(v) Application layer

(i) Physical layer: The physical layer covers the physical interface between a data transmission device (e.g. workstation, computer) and a transmission medium or network. This layer is concerned with specifying the characteristics of the transmission medium, the nature of the signals, the data rate and related matters.

(ii) Network access layer: The network access layer is concerned with the exchange of data between an end system (server, workstation, etc) and the network to which it is attached. The network access layer is concerned with access to and routing data across a network for two end systems attached to the same network.

(iii) Internet layer: The internet protocol (IP) is used at the Internet layer to provide the routing function across multiple networks. This protocol is implemented not only in the end systems but also in routers. A router is a processor that connects two networks.

(iv) Host-to-host or, transport layer: The transport layer is typically related directly with the same named layer in the OSI model. Functions include message segmentation, error detection and correction. The TCP is the most commonly used protocol to provide this functionality.

(v) Application layer: The application layer contains the logic needed to support the various user applications. For each different type of application, such as file transfer, a separate module is needed that is peculiar to the application.