TCP/IP protocols map to a four-layered conceptual model: Application, Transport, Internet, and Network Interface. This model is officially known as the TCP/IP Internet Protocol Suite but is often referred to as the TCP/IP protocol family. As shown in Figure 2.1, each layer in the TCP/IP model corresponds to one or more layers of the International Standards Organization (ISO) seven-layer Open Systems Interconnection (OSI) model.
Figure 31.1 TCP/IP and the OSI Model