ABSTRACT
The Open Systems Interconnect (OSI) reference model of the International Standards Organization divides the functions involved in the exchange of information between computer systems into seven layers, with the physical layer at the bottom and the application layer at the top. The physical layer, as its name implies, comprises the cable, connectors, and other passive components included in the cable plant that link computers and other networked end-user devices to the hubs, bridges, routers, and other active devices in the local-area network (LAN). The cable plant is often viewed by network managers as the simplest and least glamorous part of the network. Coaxial cable has a reputation among network managers as being a medium in decline, but it continues to find use in legacy data networks and was recently identified by the cable-television industry as one of the two important residential cable types to be used in hybrid fiber-coax (HFC) installations.
