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Network

A network consists of two or more computers that are connected to share resources (such as printers and CDs), exchange files, or allow electronic communications. Computers on a network can be connected through cables, telephone lines, radio waves, satellites, or rays of infrared light.

Two common types of networks:

Local area network (LAN)
Wide Area Network (WAN)

Local area network

A local area network (LAN) is a network that is limited to a relatively small area. It is usually limited to a geographic area such as a writing lab, school, or building.

Computers connected to a network are broadly classified as servers or workstations. Servers are not generally used directly by humans, but rather run continuously to provide “services” to the other computers (and their human users) on the network. The services provided may include printing and faxing, software hosting, file storage and sharing, messaging, data storage and retrieval, full access control (security) for network resources, and many others.

Workstations are so named because they typically have a human user interacting with the network through them. Workstations were traditionally considered a desktop computer, consisting of a computer, keyboard, screen, and mouse, or a laptop, with an integrated keyboard, display, and touchpad. With the advent of the tablet and touch screen devices such as iPad and iPhone, our definition of workstation is rapidly evolving to include those devices, due to their ability to interact with the network and use network services.

Servers tend to be more powerful than workstations, although configurations are driven by need. For example, a group of servers may be located in a safe area, away from humans, and can only be accessed through the network. In such cases, it would be common for servers to function without a dedicated display or keyboard. However, the size and speed of the server’s processors, hard drive, and main memory can dramatically increase the cost of the system. On the other hand, a workstation may not need as much storage or working memory, but it might require an expensive display to fit the needs of its user. Each computer on a network must be properly configured for use.

In a single LAN, computers and servers can be connected via cables or wirelessly. Wireless access to a wired network is possible through wireless access points (WAP). These WAP devices provide a bridge between computers and networks. A typical WAP may have the theoretical capacity to connect hundreds or even thousands of wireless users to a network, although the practical capacity may be much less.

Servers will almost always be wired to the network, because wired connections are still the fastest. Workstations that are stationary (desktop computers) are also often wired to the network, although the cost of wireless adapters has been reduced to the point that by installing workstations in an existing wired installation inappropriate, it may be easier and less expensive to use wireless technology for a desktop computer.

See the topology, cabling, and hardware sections of this tutorial for more information on setting up a LAN.

Wide area network

Wide Area Networks (WANs) connect networks in larger geographic areas, such as Florida, the United States, or the world. Dedicated transoceanic cabling or satellite uplinks can be used to connect this type of global network.

With a WAN, Florida schools can reach places like Tokyo in seconds, without having to pay huge phone bills. Two users half a world away with workstations equipped with microphones and webcams can teleconference in real time. A WAN is complicated. It uses multiplexers, bridges, and routers to connect local and metropolitan networks to global communications networks such as the Internet. To users, however, a WAN will not seem much different than a LAN.