Local Area Network

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A form of networking technology that implements a high-speed short distance method of computer communications, such as in a department, office, home or building.

Most LANs connect together multiple devices so that users can use, for example, one printer or one set of applications instead of having an individual printer or application on each personal computer.

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.

The most common wiring technology for a LAN is Ethernet, although wireless technologies are evolving.

3 types of Ethernet to consider:

  • Standard Ethernet - 10Base-T. Operates at 10Mbps on Unshielded Twisted Pair (UTP) Cable. Suitable for small files.
  • Fast Ethernet - 100Base-T. The most common type of Ethernet network. Supports a maximum transfer rate of 100Mbps and perfect for moving large files such as multimedia documents.
  • Gigabit Ethernet - 1000Base-T. Offers speeds of up to 1GB, perfect for video files.

Four common LAN topologies exist: bus, ring, star, and tree.

  • Bus topology - One of the most widely used LAN topologies. A linear LAN architecture in which transmissions are broadcast across the length of the channel and are received by all other nodes. Ethernet/IEEE 802.3 networks-including 100BaseT-implement a bus topology.
  • Ring topology - A series of devices connected to one another by unidirectional links forming a single closed loop. Both Token Ring/IEEE 802.5 and FDDI networks implement a ring topology.
  • Star topology - A common central hub, or switch, connects the network endpoints by dedicated links. Logical bus and ring topologies are often implemented in a star topology.
  • Tree topology - Identical to the bus topology, with the addition of branches with multiple nodes.

Benefits:

  • Information can be easily shared allowing for quick and informed decisions to be made, saving time and money.
  • A more productive and competitive environment is achieved through greater teamwork within the organisation.
  • Network-based communication such as email is considerably cheaper than using the phone or fax and sharing resources such as printers gives more efficient use of equipment at lower costs.
  • Standard versions of procedures and directories can be made accessible to everyone.
  • IT administration can be centralised.
  • Data can be backed-up from a single point on a scheduled basis ensuring consistency.
  • Everyone is working from real-time shared information and so reducing the risk of error.