쥐스킨트의 작은 서재

Wide area network

A wide area network (WAN) is a telecommunication network or computer network that extends over a large geographical distance.Wide area networks are often established with leased telecommunications circuits.

Business, education and government entitiesuse wide area networks to relay data among staff, students, clients, buyers, and suppliers from various geographical locations. In essence, this mode of telecommunication allows a business to effectively carry out its daily function regardless of location. The Internet may be considered a WAN.

Related terms for other types of networks are personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a room, building, campus or specific metropolitan area respectably.

Design options

The textbook definition of a WAN is a computer network spanning regions, countries, or even the world. However, in terms of the application of computer networking protocols and concepts, it maybe best to view WANs as computer networking technologies used to transmit data over long distances, and between different LANs, MANs and other localized computer networking architectures. This distinction stems from the fact that common LAN technologies operating at Layer 1/2 (such as the forms of Ethernet or WiFi) are often designed for physically proximal networks, and thus cannot transmit data over tens, hundreds or even thousands of miles or kilometers.

WANs do not just necessarily connect physically disparate LANs. A CAN, for example, may have a localized back bone of a WAN technology, which connects different LANs within a campus. This could be to facilitate higher bandwidth applications, or provide better functionality for users in the CAN.

WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet services providers, provide connections from an organization’s LAN to the Internet. WANs are often built using leased lines. At each end of the leased line, a router connects the LAN on one side with a second router within the LAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH, MPLS, ATM and Frame Relay are often used by service providers to deliver the links that are used in WANs.