Reference Models

The process of creating data packets is based on two connection models—the OSI and DARPA reference models. The Open Systems Interconnection (OSI) model is a standard reference model for how network data is transmitted between any two points in a computer network. TCP/IP in its most basic form supports the Defense Advanced Research Projects Agency (DARPA) model of internetworking and its network-defined layers. Much like the DARPA model, the OSI was designed to connect dissimilar computer network systems. The OSI reference model defines seven layers of functions that take place at each end of a network communication:

OSI Reference Model

TCP/IP also has a much simpler protocol model called the DARPA model:

DARPA Model