Introduction In the language of computer science, Local Area Network (LAN) is described to interconnected computers that can share data or information, resources such as scanner and printers, and applications. A Local Area Network supplies networking facility to a collection of computers in near immediacy to each other such as in an office building, a school, or a home. A LAN in turn often connects to other LANs, and to the Internet or other Wide Area Network (WAN).
Setting up a Local Area Network requires relatively cheap hardware which includes the Ethernet cables, network adapters, and hubs. An operating system is also required for some advanced configuration of the Local Area Network. Commonly, Microsoft Windows offers a software package with its operating systems which supports the control access to LAN capabilities. Most LANs attach workstations and personal computers.
Each node (individual computer) in a LAN has its own CPU with which it executes programs, but it also is able to access data and devices anywhere on the LAN. Users can also use the LAN to communicate with each other, by sending e-mail or engaging in chat sessions. Mainly, the LAN purpose today is for internet connection prior to data and application sharing.LANs are capable of transmitting data at very fast rates, much faster than data can be transmitted over a telephone line; but the distances are limited, and there is also a limit on the number of computers that can be attached to a single LAN (Fairhurst, G.
).Current LANs are most likely to be based on switched IEEE 802.3 Ethernet running at 10, 100 or 1,000 Mbit/s or on Wi-Fi technology (Wikipedia). Figure 1: A Local Area Network Scheme (Wikipedia) Commonly Used Terms in LANTopology: The geometric arrangement of devices on the network.
For example, devices can be arranged in a ring or in a straight line.Protocols: The rules and encoding specifications for sending data. The protocols also determine whether the network uses a peer-to-peer or client/server architecture.Media: Devices can be connected by twisted-pair wire, coaxial cables, or fiber optic cables.
Some networks do without connecting media altogether, communicating instead via radio waves.Although switched Ethernet is now most common at the physical and data link layers, and TCP/IP as a protocol, historically many different options have been used, and some continue to be popular in niche areas. Larger LANs may have redundant links, and routers or switches capable of using spanning tree protocol and similar techniques to recover from failed links. LANs may have connections to other LANs via routers and leased lines to create a WAN (Wide Area Network).
Most will also have connections to the large public network known as the Internet, and links to other LANs can be ‘tunneled’ across this using VPN technologies.LAN Network AddressThe first three octets of an IP address should be the same for all computers in the LAN. For example, if a total of 128 hosts exist in a single LAN, the IP addresses could be assigned starting with 192.168.
1.x, where x represents a number in the range of 1 to 128. You could create consecutive LANs within the same company in a similar manner consisting of up to another 128 computers. Of course, you are not limited to 128 computers, as there are other ranges of IP addresses that allow you to build even larger networks.
Static IP addressing means manually assigning a unique IP address to each computer in the LAN. The first three octets must be the same for each host, and the last digit must be a unique number for each host. Dynamic IP addressing is accomplished via a server or host called DHCP (Dynamic Host Configuration Program) that automatically assigns a unique IP address to each computer as it connects to the LAN.Progress in how a network routes information will allow data to move directly from a source computer to a destination computer without interference from other computers.
This will enhance the transmission of continuous streams of data, such as audio and video. The wide use of notebook and other portable computers has produced advances in wireless networks. Wireless networks use infrared or radio-frequency transmissions to connect mobile computers to networks. Infrared wireless LANs connect computers within a room, while wireless radio-frequency LANs can connect computers separated by walls.
New LAN technologies will be faster and will support multimedia applications. Asynchronous Transfer Mode (ATM) and Ethernet LANs that are 10 to 15 times faster than standard LANs are now available. To take advantage of faster LANs, computers must become faster, especially the connection called the bus that links the computer’s memory to the network. In addition, computer software must be developed that is able to efficiently transfer large amounts of data from networks to computer applications (Microsoft Encarta).
In summary, a LAN is a communications network which is:local (i.e. one building or group of buildings)controlled by one administrative authorityassumes other users of the LAN are trustedusually high speed and is always sharedLANs allow users to share resources on computers within an organization, and may be used to provide a (shared) access to remote organizations through a router connected to a Metropolitan Area Network (MAN) or a Wide Area Network (WAN).;References”Local Area Network,” Microsoft® Encarta® Online Encyclopedia 2006.
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