A local area network (LAN) is a computer network that interconnects computers within a single physical location. It is the most common type of computer network, used in homes and buildings including offices or schools, [1] [2] [3] for sharing data and devices between each other, including Internet access. Ethernet and Wi-Fi are the two most common technologies used for local area networks; historical network technologies include ARCNET, Token Ring and AppleTalk.
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A LAN contrasts a wide area network (WAN) which not only covers a larger geographic distance, but also generally involves leased telecommunication circuits.
Most wired network infrastructures utilize Category 5 or Category 6 twisted pair cabling with RJ45 compatible terminations. This medium provides physical connectivity between the Ethernet interfaces present on a large number of IP-aware devices. Depending on the grade of cable and quality of installation, speeds of up to 10 Mbit/s, 100 Mbit/s, 1 Gbit/s, or 10 Gbit/s are supported.
In a wireless LAN, users have unrestricted movement within the coverage area. Wireless networks have become popular in residences and small businesses, because of their ease of installation. Most wireless LANs use Wi-Fi as wireless adapters and which use wireless radio signal technology; the 802.11 network as certified by the IEEE. Most wireless-capable residential devices operate at a frequency of 2.4 GHz under 802.11b and 802.11g or 5 GHz under 802.11a. Some home networking devices operate in both radio-band signals and fall within the 802.11n or 802.11ac standards. Wi-Fi is a marketing and compliance certification for IEEE 802.11 technologies. [4] The Wi-Fi Alliance has tested compliant products, and certifies them for interoperability. The technology may be integrated into smartphones, tablet computers and laptops. Guests are often offered Internet access via a hotspot service.
Simple LANs in office or school buildings generally consist of cabling and one or more network switches; a switch is used to allow devices on a LAN to talk to one another via Ethernet. A switch can be connected to a router, cable modem, or ADSL modem for Internet access. LANs at residential homes usually tend to have a single router and often may include a wireless repeater. A LAN can include a wide variety of other network devices such as firewalls, load balancers, and network intrusion detection. [5] A wireless access point is required for connecting wireless devices to a network; when a router includes this device, it is referred to as a wireless router.
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 VLANs. A network bridge binds two different network interfaces 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, bus, mesh and star. 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). [6]
DHCP is used to assign internal IP addresses to members of a local area network. A DHCP server typically runs on the router [7] with end devices as its clients. All DHCP clients request configuration settings using the DHCP protocol in order to acquire their IP address, a default route and one or more DNS server addresses. Once the client implements these settings, it will be able to communicate on that internet. [8]
At the higher network layers, protocols such as NetBIOS, IPX/SPX, AppleTalk and others were once common, but the Internet protocol suite (TCP/IP) has prevailed as the standard of choice for almost all local area networks today.
LANs can maintain connections with other LANs via leased lines, leased services, or across the Internet using virtual private network technologies. Depending on how the connections are established and secured, and the distance involved, such linked LANs may also be classified as a metropolitan area network (MAN) or a wide area network (WAN).
Local area networks may be connected to the Internet (a type of WAN) via fixed-line means (such as a DSL/ADSL modem [9] ) or alternatively using a cellular or satellite modem. These would additionally make use of telephone wires such as VDSL and VDSL2, coaxial cables, or fiber to the home for running fiber-optic cables directly into a house or office building, or alternatively a cellular modem or satellite dish in the latter non-fixed cases. With Internet access, the Internet service provider (ISP) would grant a single WAN-facing IP address to the network. A router is configured with the provider's IP address on the WAN interface, which is shared among all devices in the LAN by network address translation.
A gateway establishes physical and data link layer connectivity to a WAN over a service provider's native telecommunications infrastructure. Such devices typically contain a cable, DSL, 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 switch.
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. [10] [ relevant? ]
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The increasing demand and usage of computers in universities and research labs in the late 1960s generated the need to provide high-speed interconnections between computer systems. A 1970 report from the Lawrence Radiation Laboratory detailing the growth of their "Octopus" network gave a good indication of the situation. [11] [12]
A number of experimental and early commercial LAN technologies were developed in the 1970s. Ethernet was developed at Xerox PARC between 1973 and 1974. [13] [14] Cambridge Ring was developed at Cambridge University starting in 1974. [15] ARCNET was developed by Datapoint Corporation in 1976 and announced in 1977. [16] It had the first commercial installation in December 1977 at Chase Manhattan Bank in New York. [17] In 1979, [18] the Electronic voting systems 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.[ dubious – discuss ] It was using 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. [19]
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". [20] [21] [22]
In practice, the concept was marred by the proliferation of incompatible physical layer and network protocol implementations, and a plethora of methods of sharing resources. Typically, each vendor would have its own type of network card, cabling, protocol, and network operating system. A solution appeared with the advent of Novell NetWare which provided even-handed support for dozens of competing card and cable types, and a much more sophisticated operating system than most of its competitors.
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. [23]
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. [24] [25] The TCP/IP-based LAN successfully supported Telnet, FTP, and a Defense Department teleconferencing application. [26] 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. [27] However, WWMCCS was superseded by the Global Command and Control System (GCCS) before that could happen.
During the same period, Unix workstations 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, NBF, 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. [28] [29]
In the 1980s, several token ring network implementations for LANs were developed. [30] [31] IBM released their own implementation of token ring in 1985, [32] [33] It ran at 4 Mbit/s . [34] IBM claimed that their token ring systems were superior to Ethernet, especially under load, but these claims were debated. [35] [36] IBM's implementation of token ring was the basis of the IEEE 802.5 standard. [37] A 16 Mbit/s version of Token Ring was standardized by the 802.5 working group in 1989. [38] IBM had market dominance over Token Ring, for example, in 1990, IBM equipment was the most widely used for Token Ring networks. [39]
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. [40] FDDI installations have largely been replaced by Ethernet deployments. [41]
Ethernet is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3. Ethernet has since been refined to support higher bit rates, a greater number of nodes, and longer link distances, but retains much backward compatibility. Over time, Ethernet has largely replaced competing wired LAN technologies such as Token Ring, FDDI and ARCNET.
A MAC address is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. This use is common in most IEEE 802 networking technologies, including Ethernet, Wi-Fi, and Bluetooth. Within the Open Systems Interconnection (OSI) network model, MAC addresses are used in the medium access control protocol sublayer of the data link layer. As typically represented, MAC addresses are recognizable as six groups of two hexadecimal digits, separated by hyphens, colons, or without a separator.
A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, or office building. This gives users the ability to move around within the area and remain connected to the network. Through a gateway, a WLAN can also provide a connection to the wider Internet.
Wake-on-LAN is an Ethernet or Token Ring computer networking standard that allows a computer to be turned on or awakened from sleep mode by a network message. It is based upon AMD's Magic Packet Technology, which was co-developed by AMD and Hewlett-Packard, following its proposal as a standard in 1995. The standard saw quick adoption thereafter through IBM, Intel and others.
Fiber Distributed Data Interface (FDDI) is a standard for data transmission in a local area network. It uses optical fiber as its standard underlying physical medium.
A cable modem is a type of network bridge that provides bi-directional data communication via radio frequency channels on a hybrid fiber-coaxial (HFC), radio frequency over glass (RFoG) and coaxial cable infrastructure. Cable modems are primarily used to deliver broadband Internet access in the form of cable Internet, taking advantage of the high bandwidth of a HFC and RFoG network. They are commonly deployed in the Americas, Asia, Australia, and Europe.
Wi-Fi is a family of wireless network protocols based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio waves. These are the most widely used computer networks, used globally in home and small office networks to link devices and to provide Internet access with wireless routers and wireless access points in public places such as coffee shops, restaurants, hotels, libraries, and airports.
The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer provides the functional and procedural means to transfer data between network entities and may also provide the means to detect and possibly correct errors that can occur in the physical layer.
In computer networking, a wireless access point (WAP) is a networking hardware device that allows other Wi-Fi devices to connect to a wired network or wireless network. As a standalone device, the AP may have a wired or wireless connection to a switch or router, but in a wireless router it can also be an integral component of the networking device itself. A WAP and AP is differentiated from a hotspot, which can be a physical location or digital location where Wi-Fi or WAP access is available.
A network interface controller is a computer hardware component that connects a computer to a computer network.
Internet access is a facility or service that provides connectivity for a computer, a computer network, or other network device to the Internet, and for individuals or organizations to access or use applications such as email and the World Wide Web. Internet access is offered for sale by an international hierarchy of Internet service providers (ISPs) using various networking technologies. At the retail level, many organizations, including municipal entities, also provide cost-free access to the general public. Types of connections range from fixed-line cable to mobile and satellite.
A wireless gateway routes packets from a wireless LAN to another network, wired or wireless WAN. It may be implemented as software or hardware or a combination of both. Wireless gateways combine the functions of a wireless access point, a router, and often provide firewall functions as well. They provide network address translation (NAT) functionality, so multiple users can use the internet with a single public IP. It also acts like a dynamic host configuration protocol (DHCP) to assign IPs automatically to devices connected to the network.
A wireless router or Wi-Fi router is a device that performs the functions of a router and also includes the functions of a wireless access point. It is used to provide access to the Internet or a private computer network. Depending on the manufacturer and model, it can function in a wired local area network, in a wireless-only LAN, or in a mixed wired and wireless network.
A digital subscriber line (DSL) modem is a device used to connect a computer or router to a telephone line which provides the digital subscriber line (DSL) service for connection to the Internet, which is often called DSL broadband. The modem connects to a single computer or router, through an Ethernet port, USB port, or is installed in a computer PCI slot.
A home network or home area network (HAN) is a type of computer network, specifically a type of local area network (LAN), that facilitates communication among devices within the close vicinity of a home. Devices capable of participating in this network, for example, smart devices such as network printers and handheld mobile computers, often gain enhanced emergent capabilities through their ability to interact. These additional capabilities can be used to increase the quality of life inside the home in a variety of ways, such as automation of repetitive tasks, increased personal productivity, enhanced home security, and easier access to entertainment.
A computer network is a set of computers sharing resources located on or provided by network nodes. Computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies based on physically wired, optical, and wireless radio-frequency methods that may be arranged in a variety of network topologies.
Token Ring is a physical and data link layer computer networking technology used to build local area networks. It was introduced by IBM in 1984, and standardized in 1989 as IEEE 802.5. It uses a special three-byte frame called a token that is passed around a logical ring of workstations or servers. This token passing is a channel access method providing fair access for all stations, and eliminating the collisions of contention-based access methods.
Data center bridging (DCB) is a set of enhancements to the Ethernet local area network communication protocol for use in data center environments, in particular for use with clustering and storage area networks.
HYPERchannel, sometimes rendered Hyperchannel, was a local area networking system for mainframe computers, especially supercomputers, introduced by Network Systems Corporation in the 1970s. It ran at the then-fast speed of 50 Mbits/second, performance that would not be matched by commodity hardware until the introduction of Fast Ethernet in 1995. HYPERchannel ran over very thick coax cable or fibre optic extensions and required adaptor hardware the size of a minicomputer. The networking protocol was entirely proprietary. Solutions for Control Data, IBM and Cray computers were their primary products, but a wide variety of support emerged in the 1980s, including DEC VAX and similar superminicomputers.
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: CS1 maint: DOI inactive as of November 2024 (link) CS1 maint: multiple names: authors list (link) CS1 maint: numeric names: authors list (link)'The Year of The LAN' is a long-standing joke, and I freely admit to being the comedian that first declared it in 1982...
...you will remember numerous computer magazines, over numerous years, announcing 'the year of the LAN.'
...a bit like the Year of the LAN which computer industry pundits predicted for the good part of a decade...