Data Communications Networking Devices: Operation, Utilization and Lan and Wan Internetworking, 4th Edition

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WIDE AREA NETWORK DATA CONCENTRATION EQUIPMENT

The communications devices included in this chapter perform a variety of functions which govern their utilization for selected application areas, with their inclusion here based upon their common function of concentrating data. In this chapter, the operation and utilization of devices designed primarily to accomplish data concentration will be covered. Specific devices to be investigated in this chapter include a variety of multiplexing equipment, concentrators, and front-end processors, as well as equipment which permits modems, service units, lines, and the ports of the computers and other devices to operate on a shared use basis. In addition, a device which splits a data stream into two streams for transmission to take advantage of the difference in the tariff between high-speed and lower operating rate leased lines will also be covered.

Although the title of this chapter includes the term ‘wide area network’, this term is included only because the primary function of each device is to concentrate two or more data sources for transmission over a wide area network transmission facility. Thus, the title does not imply that these devices cannot be used to interconnect LANs. In fact, several devices covered in this chapter, including different types of multiplexers, packet assembler/disassemblers, Frame Relay Access Devices, control units, and front-end processors either directly or indirectly enable LANs to be interconnected over a ...