Product Code Database
A local area network ( LAN) is a computer network that interconnects computers within a limited area such as a residence, campus, or building, and has its network equipment and interconnects locally managed. LANs facilitate the distribution of data and sharing network devices, such as printers.
The LAN contrasts the wide area network (WAN), which not only covers a larger geographic distance, but also generally involves Leased line or Internet links. An even greater contrast is the Internet, which is a system of globally connected business and personal computers.
Ethernet and Wi-Fi are the two most common technologies used for local area networks; historical network technologies include ARCNET, Token Ring, and LocalTalk.
Advanced LANs are characterized by their use of redundant links with switches using the Spanning Tree Protocol to prevent loops, their ability to manage differing traffic types via quality of service (QoS), and their ability to segregate traffic with . A network bridge binds two different LANs or LAN segments to each other, often in order to grant a wired-only device access to a wireless network medium.
Network topology describes the layout of interconnections between devices and network segments. At the data link layer and physical layer, a wide variety of LAN topologies have been used, including ring network, bus network, mesh network and star network. The star topology is the most common in contemporary times. Wireless LAN (WLAN) also has its topologies: independent basic service set (IBSS, an ad-hoc network) where each node connects directly to each other (this is also standardized as Wi-Fi Direct), or basic service set (BSS, an infrastructure network that uses an wireless access point).
A gateway establishes Physical layer and data link layer connectivity to a WAN over a service provider's native telecommunications infrastructure. Such devices typically contain a Cable modem, DSL modem, or optical modem bound to a network interface controller for Ethernet. Home and small business class routers are often incorporated into these devices for additional convenience, and they often also have integrated wireless access point and 4-port Ethernet LAN switching.
The ITU-T G.hn and IEEE Powerline standard, which provide high-speed (up to 1 Gbit/s) local area networking over existing home wiring, are examples of home networking technology designed specifically for IPTV delivery. (2014). 9781466557529, CRC Press. ISBN 9781466557529
A number of experimental and early commercial LAN technologies were developed in the 1970s. Ethernet was developed at Xerox PARC between 1973 and 1974. Archived at Ghostarchive and the Wayback Machine The Cambridge Ring was developed at Cambridge University starting in 1974. ARCNET was developed by Datapoint Corporation in 1976 and announced in 1977. It had the first commercial installation in December 1977 at Chase Manhattan Bank in New York. In 1979, the electronic voting system for the European Parliament was the first installation of a LAN connecting hundreds (420) of microprocessor-controlled voting terminals to a polling/selecting central unit with a multidrop bus with Master/slave (technology) arbitration. It used 10 kilometers of simple unshielded twisted pair category 3 cable—the same cable used for telephone systems—installed inside the benches of the European Parliament Hemicycles in Strasbourg and Luxembourg.
The development and proliferation of personal computers using the CP/M operating system in the late 1970s, and later DOS-based systems starting in 1981, meant that many sites grew to dozens or even hundreds of computers. The initial driving force for networking was to share storage and printers, both of which were expensive at the time. There was much enthusiasm for the concept, and for several years, from about 1983 onward, computer industry pundits habitually declared the coming year to be, "The year of the LAN".
Of the competitors to NetWare, only Banyan Vines had comparable technical strengths, but Banyan never gained a secure base. 3Com produced 3+Share and Microsoft produced MS-Net. These then formed the basis for collaboration between Microsoft and 3Com to create a simple network operating system LAN Manager and its cousin, IBM's LAN Server. None of these enjoyed any lasting success; Netware dominated the personal computer LAN business from early after its introduction in 1983 until the mid-1990s when Microsoft introduced Windows NT.
In 1983, TCP/IP was first shown capable of supporting actual defense department applications on a Defense Communication Agency LAN testbed located at Reston, Virginia. The TCP/IP-based LAN successfully supported Telnet, FTP, and a Defense Department teleconferencing application. This demonstrated the feasibility of employing TCP/IP LANs to interconnect Worldwide Military Command and Control System (WWMCCS) computers at command centers throughout the United States. However, WWMCCS was superseded by the Global Command and Control System (GCCS) before that could happen.
During the same period, were using TCP/IP networking. Although the workstation market segment is now much reduced, the technologies developed in the area continue to be influential on the Internet and in all forms of networking—and the TCP/IP protocol has replaced IPX, AppleTalk, NetBIOS Frames, and other protocols used by the early PC LANs.
Econet was Acorn Computers's low-cost local area network system, intended for use by schools and small businesses. It was first developed for the Acorn Atom and Acorn System 2/3/4 computers in 1981.
Fiber Distributed Data Interface (FDDI), a LAN standard, was considered an attractive campus backbone network technology in the early to mid 1990s since existing Ethernet networks only offered 10 Mbit/s data rates and Token Ring networks only offered 4 Mbit/s or 16 Mbit/s rates. Thus it was a relatively high-speed choice of that era, with speeds such as 100 Mbit/s. By 1994, vendors included Cisco Systems, National Semiconductor, Network Peripherals, SysKonnect (acquired by Marvell Technology Group), and 3Com. FDDI installations have largely been replaced by Ethernet deployments.
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