3.1 Local Area Network (LAN)

Local Area Network (LAN)

 Local Area Network (LAN)

A local area network (LAN) supplies networking capability to a group of computers in close proximity to each other such as in an office building, a school, or a home. A LAN is useful for sharing resources like files, printers, games or other applications. A LAN in turn often connects to other LANs, and to the Internet or other WAN.

Most local area networks are built with relatively inexpensive hardware such as Ethernet cables, network adapters, and hubs. Wireless LAN and other more advanced LAN hardware options also exist.

Specialized operating system software may be used to configure a local area network. For example, most flavors of Microsoft Windows provide a software package called Internet Connection Sharing (ICS)that supports controlled access to LAN resources.

The term LAN party refers to a multiplayer gaming event where participants bring their own computers and build a temporary LAN.

Bandwidth of LAN is 5 GHz to 50 GHz.

Examples:

The most common type of local area network is an Ethernet LAN. The smallest home LAN can have exactly two computers; a large LAN can accommodate many thousands of computers. Many LANs are divided into logical groups called subnets. An Internet Protocol (IP) "Class A" LAN can in theory accommodate more than 16 million devices organized into subnets.

Advantages

1. A typical LAN network structureHardware such as printers can be shared so individual workstations do not need their own printer. When they print, the data is stored in a queue on a server. The data is then passed to the printer.
2. All the users work can be stored in a central place (the dedicated file server) so a user can access their work through any computer on the network.
3. Software can be shared, software packages are stored on the server and downloaded to workstations as requested. Note that a licence still has to be bought for each copy of the software needed.
4. Data can be shared because database files stored in the server are available to users around the network; data from CD-ROMs can also be shared across the network.
5. Central back-up can take place automatically at regular intervals. A user will usually be able to retrieve work that has been deleted by mistake.
6. Messages can be sent to people working at other computers on the network which can save time and paper.
7. It is possible to set up a local intranet such as that on the KLB school network. The web pages of information can be accessed only over the LAN.  An intranet is free because it does not involve phone links.
8. There is control over users’ access rights to programs and data.

Disadvantages

1. Printing can be slow. Where a lot of workstations are served by only one or two printers, long print queues may develop.
2. A virus can spread more easily. If a virus gets into one computer, it is likely to spread quickly across the network because it will get into the central backing store.
3. As data is shared there is a greater need for security. Users of the network have to have authentication techniques such as user ids and passwords. Unique user ID's control access to the files and settings on the network while passwords prevent unauthorised users from logging onto the network.  Data may also have to be encrypted so that it is meaningless if intercepted.
4. If the server fails, all the workstations are affected. Work stored on shared hard disk drives will not be accessible and it will not be possible to use network printers either.
5. The cost of installing the equipment is greater. Cabling can be expensive to buy and to install.
6. Damage to cables can isolate computers. Some sections of the network can become isolated and will not be able to communicate with the rest of the network.
7. Because networks can be complicated to maintain, a network manager may be need to be employed to run the system.