Wide area networks (WANS)
Wide area networks (WANS)A Wide Area Network (WAN) is a network that spans a large geographical area, the most common example being the Internet. A WAN is contrasted to smaller local area networks (LANs) and metropolitan area networks (MANs). LANs are home or office networks, while a MAN might encompass a campus or service residents of a city, such as in a citywide wireless or WiFi network.
The Internet is a public WAN, but there are many ways to create a business model or private WAN. A private WAN is essentially two or more LANs connected to each other. For example, a company with offices in Los Angeles, Texas and New York might have a LAN setup at each office. Through leased telephone lines, all three LANs can communicate with each other, forming a WAN.
Routers are used to direct communications between LANs communicating on a WAN. The router, installed on the leased line, reads the "envelopes" or headers on each packet of data that passes through the WAN, sending it to the proper LAN. When the packet arrives at the LAN, a device called a switch sends the data packet on to the correct machine. Hence, the WAN acts like an interface between LANs for long-distance communication. A WAN that runs on a leased line is a private WAN, as there is no public traffic on the line.
Because leased lines are expensive, many businesses that require a WAN use an Internet Service Provider (ISP) to provide WAN access instead. In this case, each LAN in the WAN communicates through a standard digital subscriber line (DSL) account. The DSL Internet account uses an existing telephone line while sharing that line with the telephone.
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