Chapter 3 - TCP/IP and the OSI Model

Abstract

Communications between networks via the Internet are accomplished using the Transmission Control Protocol/Internet Protocol (TCP/IP) suite. As a result, the success of network depends on the understanding of how the protocol suite functions and knowing the network design requirements, such as an IP addressing scheme and routing protocols. The IP suite includes IP addressing, routing protocols, and troubleshooting. The Open Systems Interconnection (OSI) model is composed of seven layers, consisting of the physical, data-link, network, transport, session, presentation, and application layers. The Department of Defense (DoD) chose to use four layers and applied it specifically to IP and the Internet. The DoD model consists of the network access layer, Internet layer, host-to-host layer, and the applications layer. Understanding these models and how they interact is the basis for understanding TCP/IP. This chapter focuses on the applications that help support and maintain the Internet and IP. Various protocols make up the suite known as TCP/IP. Although TCP/IP is a fully implemented and robust technology, enhancements and modifications are still under way, attempting to make it even better than it is today. IPv6 is expected to provide a new suite of additions to the existing ones.