Wide Area Network (WAN) Infrastructure
Introduction
A wide area network, or WAN (wide area network in English), is a computer network that unites and interconnects several networks of larger geographic scope, for example local area networks, although its members are not all in the same physical location.
Many WANs are built by organizations or companies for their private use, others are installed by Internet Service Providers (ISP) to provide connection to their customers.
Today, the Internet provides high-speed connections, so a high percentage of WAN networks are based on that medium, reducing the need for private WAN networks, while virtual private networks use encryption "Encryption (cryptography)") and other techniques to generate a dedicated network over Internet communications.
Definition
WANs do not necessarily have to be connected to LANs. For example, you may have a localized skeleton 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.
WANs are used to connect LANs and other types of networks. This way users can communicate with users and teams in other places. Many WANs are built by a particular organization and are private. Others, built by Internet service providers, provide LAN connections to an Internet organization. WANs are often built using leased lines. At each end of the leased line, a router connects the LAN on one side to a second router within the LAN on the other.[1] Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less expensive circuit switching or packet switching methods. Network protocols, including TCP/IP, have transport delivery function and addressing functions. Protocols, including packages such as SONET/SDH, MPLS, ATM, and Frame Relay, are often used by service providers that provide the links used in WAN networks. X.25 was soon an important WAN protocol, and is often considered the "grandfather" of Frame Relay, as many of the underlying protocols and features of X.25 are still in use today (with updates) by Frame Relay.
Academic research on wide area networks can be divided into three areas: mathematical modeling, network emulation and network simulation.
Performance improvements are sometimes delivered through wide area file services or by WAN optimization services.