Wide Area Networks
A wide area network is a network spread over a larger area than a LAN. A wide area network will typically consist of two or more LAN's linked together. Another main difference between the local area networks and the wide area networks is the fact that the wide area network uses switching equipment. WAN's can and will usually be spread over different countries. For communication purposes a WAN will be ideal for a company that may be based in the United States but has an office in the U.K. If this is the case the organizations in question will need to communicate. A WAN is an ideal solution for a company that needs a constant flow of digital information between the 2 offices. If the WAN is set up for a company the company will use its own servers etc. This is usually the case as it keeps the network independent and also means that the companies own engineers can work on any problems which may arise.
WAN technologies function at the lower three layers of the OSI reference model: the physical layer, the data link layer, and the network layer. A point-to-point link provides a single, pre-established WAN communications path from the customer premises through a carrier network, such as a telephone company, to a remote network. A point-to-point link is also known as a leased line because its established path is permanent and fixed for each remote network reached through the carrier facilities. The carrier company reserves point-to-point links for the private use of the customer. These links accommodate two types of transmissions: datagram transmissions, which are composed of individually addressed frames, and data-stream transmissions, which are composed of a stream of data for which address checking occurs only once.
Circuit switching is a WAN...