Local Area Networks: An Overview
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The Need for LANs
Perhaps the driving force behind the widespread use of LANs is the dramatic and continuing decrease in computer hardware costs, accompanied by an increase in computer hardware capability. Year by year, the cost of computer systems continues to drop dramatically while the performance and capacity of those systems continue to rise equally dramatically. This ongoing technological revolution has enabled the development of applications of astounding complexity and power. For example, desktop applications that require the great power of today's microprocessor-based systems include the following:
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Image processing
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Speech recognition
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Videoconferencing
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Multimedia authoring
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Voice and video annotation of files
Workstation systems now support highly sophisticated engineering and scientific applications, as well as simulation systems, and the ability to apply workgroup principles to image and video applications. In addition, businesses are relying on increasingly powerful servers to handle transaction and database processing and to support massive client/server networks that have replaced the huge mainframe computer centers of yesteryear.
All of these factors lead to an increased number of systems, with increased power, at a single site: office building, factory, operations center, and so on. At the same time, there is an absolute requirement to interconnect these systems to share and exchange data among systems, and to share expensive resources.
The need to share data is a compelling reason for interconnection. Individual users of computer resources don't work in isolation. They need facilities to exchange messages with other users, to access data from several sources in the preparation of a document or for an analysis, and to share project-related information with other members of a workgroup.
The need to share expensive resources is another driving factor in the development of networks. The cost of processor hardware has dropped far more rapidly than the cost of mass storage devices, video equipment, printers, and other peripheral devices. The result is a need to share these expensive devices among a number of users to justify the cost of the equipment. This sharing requires some sort of client/server architecture operating over a LAN that interconnects users and resources.