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external image icon60_shr.gifA computer network is composed of multiple connected computers that communicate over a wired or wireless medium to share data and other resources. For instance, a home computer network may consist of two or more computers that share files and a printer using the network. The size and scalability of any computer network are determined both by the physical medium of communication and by the software controlling the communication (i.e., the protocols).

An intranet is a set of interconnected networks, using the Internet Protocol and uses IP-based tools such as web browsers, that is under the control of a single administrative entity. That administrative entity closes the intranet to the rest of the world, and allows only specific users. Most commonly, an intranet is the internal network of a company or other enterprise.

A extranet is network or internetwork that is limited in scope to a single organization or entity but which also has limited connections to the networks of one or more other usually, but not necessarily, trusted organizations or entities (e.g., a company's customers may be provided access to some part of its intranet thusly creating an extranet while at the same time the customers may not be considered 'trusted' from a security standpoint). Technically, an extranet may also be categorized as a CAN, MAN, WAN, or other type of network, although, by definition, an extranet cannot consist of a single LAN, because an extranet must have at least one connection with an outside network.

A specific internetwork, consisting of a worldwide interconnection of governmental, academic, public, and private networks based upon the Advanced Research Projects Agency Network (ARPANET) developed by ARPA of the U.S. Department of Defense – also home to the World Wide Web (WWW) and referred to as the 'Internet' with a capital 'I' to distinguish it from other generic internetworks. Participants in the Internet, or their service providers, use IP Addresses obtained from address registries that control assignments. Service providers and large enterprises also exchange information on the reachability of their address ranges through the Border Gateway Protocol.

There are also other types of network such as the following:

  • Personal Area Network (PAN)
A personal area network (PAN) is a computer network used for communication among computer devices (including telephones and personal digital assistants) close to one person.

  • Local Area Network (LAN)
A network covering a small geographic area, like a home, office, or building.

  • Campus Area Network (CAN)
A network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, or a military base.
  • Metropolitan Area Network (MAN)
A network that connects two or more Local Area Networks or CAN together but does not extend beyond the boundaries of the immediate town, city, or metropolitan area. Multiple routers, switches & hubs are connected to create a MAN

  • Wide Area Network (WAN)
A WAN is a data communications network that covers a relatively broad geographic area (i.e. one country to another and one continent to another continent) and that often uses transmission facilities provided by common carriers, such as telephone companies.
  • Global Area Network (GAN)
Global area networks (GAN) specifications are in development by several groups, and there is no common definition.


external image icon60_pub.gifFour tips for building better wireless networks

How much performance capability do companies expect when they deploy a wireless network? Chances are, not enough -- especially as wireless becomes a mainstream part of the New Data Center infrastructure.
"It's a misconception -- a very common one -- that wireless LAN performance is always poor," says David Newman, a Network World Test Alliance partner and president of Network Test. "People say, 'It's just wireless; what do you expect?' In fact, wireless LANs can be made to perform quite well, but it does involve thinking some about network design."
Here then, courtesy of Newman and other wireless experts, are four tips for optimizing a wireless network and improving application performance. (extract of article by Jon Brodkin, NetworkWorld)