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Embed code for: 22.2 Introduction to WANs
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22.2 Introduction to WANs
Introduction to WANs Section 22: Introducing WAN Technologies A WAN is a data communication network that connects networks beyond the geographic scope of a LAN. WANs use the facilities of a service provider or carrier such as a telephone or cable company. They connect geographically remote locations of an organization. WANs are frequently used for businesstobusiness connections for data exchange, to external services, and to remote users. WANs carry traffic types such as voice, data, and video. There are three major characteristics of WANs: WANs connect devices that are located over wide geographical areas. WANs use the services of carriers such as telephone companies, cable companies, satellite systems, and network providers. WANs use various connection types to provide access to bandwidth over large geographical areas. Why Are WANs Needed? There are several reasons why WANs are necessary in a communications environment. LAN technologies provide both speed and costeffectiveness for transmission of data in organizations in relatively small geographic areas. However, other business needs require communication among remote users: People in regional or branch offices of an organization need to be able to communicate and share data. Organizations often want to share information with other organizations across large distances. For example, software manufacturers routinely communicate product and promotion information to distributors that sell their products to end users. Employees who travel on company business or work from home frequently need to access information that resides on their corporate networks. Scaling to connect computers across a country or around the world is not feasible. Various WAN technologies have evolved to allow organizations and individuals to meet their widearea communications needs. LANs vs. WANs WANs are different from LANs in several ways. The most significant differences between WANs and LANs are related to their geographical scope and to ownership. A LAN connects computers, peripherals, and other devices in a single building or other small geographic area. A WAN allows the transmission of data across long distances. A company or organization also must subscribe to an outside WAN service provider to use WAN carrier network services. LANs typically are owned by the company or organization that uses them. LANs usually require a onetime investment, and WAN services normally involve recurring monthly service fees paid to a service provider. Since 2000, technologies such as IPsec VPN and SSL VPN have emerged to leverage the Internet as a costeffective alternative to traditional WAN connections. LAN vs WAN Differences Scope WANs LANs Scope WANs LANs Area Wide geographic area Single building or small geographic area Ownership Subscription to outside service provider Owned by organization Cost Recurring Fixed Privately owned WANs are expensive to develop and maintain and thus usually are found only in large organizations. Most companies purchase WAN connections from a service provider or ISP. The service provider is then responsible for maintaining the backend network connections and network services between the LANs. For globally distributed organizations, establishing WAN connectivity can be complicated. For example, the major service provider for the organization may not offer service in every location where the organization has an office. The organization must then purchase services from multiple service providers. Because local laws and communication infrastructure can vary greatly from country to country, network architects need to plan carefully to maintain a consistent quality of service at each site. In many emerging countries, for example, network designers find differences in equipment availability, WAN services that are offered, and encryption strength allowed by law. Although having uniform standards for equipment, configuration, and services is important, exceptions may be necessary when multiple service providers are used. Up Next: The Role of Routers on WANs