See W. Stallings, Local and Metropolitan Area Networks (1993); M. N. O. Sadiku, Metropolitan Area Networks (1995).
A local area network (LAN) is a computer network covering a small physical area, like a home, office, or small group of buildings, such as a school, or an airport. The defining characteristics of LANs, in contrast to wide-area networks (WANs), include their usually higher data-transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines.
Ethernet was developed at Xerox PARC in 1973–1975, and filed as . In 1976, after the system was deployed at PARC, Metcalfe and Boggs published their seminal paper - "Ethernet: Distributed Packet-Switching For Local Computer Networks"''
The development and proliferation of CP/M-based personal computers from the late 1970s and then DOS-based personal computers a from 1981 meant that a single site began to have dozens or even hundreds of computers. The initial attraction of networking these was generally to share disk space and laser printers, which were both very expensive at the time. There was much enthusiasm for the concept and for several years, from about 1983 onward, computer industry pundits would regularly declare 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. Microsoft and 3Com worked together to create a simple network operating system which formed the base of 3Com's 3+Share, Microsoft's LAN Manager and IBM's LAN Server. None of these were particularly successful.
In this same timeframe, Unix computer workstations from vendors such as Sun Microsystems, Hewlett-Packard, Silicon Graphics, Intergraph, NeXT and Apollo were using TCP/IP based networking. Although this market segment is now much reduced, the technologies developed in this area continue to be influential on the Internet and in both Linux and Apple Mac OS X networking—and the TCP/IP protocol has now almost completely replaced IPX, AppleTalk, NBF and other protocols used by the early PC LANs. A TCP/IP based LAN is also known as an Intranet.
Larger 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 to segregate traffic via VLANs. Larger LANS also contain a wide variety of network devices such as switches, firewalls, routers, load balancers, sensors and so on.
LANs may have connections with other LANs via leased lines, leased services, or by 'tunneling' across the Internet using VPN technologies. Depending on how the connections are made and secured, and the distance involved, they become a Metropolitan Area Network (MAN), a Wide Area Network (WAN), or a part of the internet.