 government or an industrial enterprise. FTS2000, the large GSA (General Services Administration) that was chartered to serve all U.S. government organizations, is an example of a broad interpretation. This network provides multiple services: voice data and image. It is the U.S. government's own PSTN. A narrow interpretation might be Corrugated Box Works local area network. Or Walgreens' large VSAT network. This latter example is included because the network serves a singular purpose, for logistics and cash flow, and is owned by one entity. This chapter will be based on the narrower interpretation and will be confined to the various data networks that may be employed in government and industry. We first present an overview of local area networks (LANs) followed by a discussion in the next chapter of wide area networks (WANs). 11.2 LOCAL AREA NETWORKS (LANS) The IEEE (Ref. 1) defines a local area network as "a communication network to inter- connect a variety of devices (e.g., personal computers, workstations, printers, file storage devices) that can transmit data over a limited area, typically within a facility." The geographical extension or "local area" may extend from less than 100 ft (< 30 m) to over 6 miles (> 10 km). More commonly we can expect a LAN to extend over a floor in a building, and in some cases over a portion of a floor. Other LANs may cover multiple floors, groups of building in the same general area, or a college or industrial campus. The transmission media encompass wire pair, coaxial cable, fiber-optic cable, and radio. The implementation of coaxial cable systems is slowing in favor of high-quality twisted wire pair. Wireless LANs, particular in the IEEE 802.11 series standards, are reaching maturity. Data rates vary from 1 Mbps to 1000 Mbps. LAN data rates, the number of devices connected to a LAN, the spacing of those devices, and the network extension depend on: Fundamentals of Telecommunications, Second Edition, by Roger L. Freeman ISBN 0-471-71045-8 Copyright © 2005 by Roger L. Freeman E