Internetworking

As local area networks become more and more prevalent and increasingly vital to the daily operation of an organization, the need to connect multiple LANs together has become as crucial as it once was to link individual PCs into a workgroup. More and more, it's likely that a worker linked into a firm's marketing department workgroup requires access to resources located on another LAN within the company a database in the engineering network, for example.

This need has spawned one of the fastest growing areas of the LAN industry: The internetworking marketplace, composed principally of repeaters, bridges, routers, gateways, and, most recently, hybrid products called brouters and routing bridges. Internetworking products bring interconnectivity to workers linked into large, spread-out groups of LANs. They also play a major role in network management by allowing network administrators to segment, or divide, a single network into an assembly of multiple subnetworks. This subdivision can improve network performance limiting the number of nodes on a network can reduce traffic over the workgroup wiring. It also facilitates security internetworking allows restricting individuals to specified resources and increases system reliability when one workgroup goes down, it doesn't affect the entire network.

There are four primary types of internetworking products: repeaters, bridges, routers, and gateways (see Figures 1 4). (Beginning in 1994 or so, multiport bridges began to be marketed as switches, but switches usually provide the same fundamental functions as the devices traditionally known as bridges. In some cases, switches actually perform local routing functions as well.) Each internetwork product...