Wide Area Network

A Wide Area Network (WAN, dt Wide Area Network ) is a computer network which extends in contrast to a LAN or MAN over a very large geographic area.

The number of connected computers is unlimited. WANs extend across countries or even continents. WANs are used to connect different LANs, but also individual computers together. Some WANs are certain organizations and are used exclusively by them. Other WANs are built by Internet service providers or extended in order to offer access to the Internet.

A wide area network operating on the physical layer and the data link layer of the OSI reference model. Because of the large number of connected computers that unaddressed sending information ( Broadcasting) to all computers is hardly efficient. Therefore, data is sent only to the receiver. For a uniform addressing scheme is necessary. In addition, there must be, forward the data packets sent to the correct address between systems. Such intermediate systems are switches, packet switch, bridges and routers.

The WAN technologies include IP / MPLS and Ethernet, as well as technologies such as Plesiochronous Digital Hierarchy (PDH ), Synchronous Digital Hierarchy (SDH ), the somewhat dated Asynchronous Transfer Mode (ATM) and X.25 are among them.