A Wide Area Network is a network that spans a large geographic area. WANs connect multiple smaller networks, such as LANs (Local Area Networks) or MANs (Metropolitan Area Networks). The World Wide Internet is the world's most popular and largest WAN. WANs are often used as connection of LANs within an organization over larger geographical area. A router connects LANs to a WAN. The equipment for WANs are more expensive than LANs.
LAN:
WAN connects the LANs, from different geographical locations, together in order for them to communicate with one another.
There are four major types of WAN connections available.
- Dedicated Leased Line: This is point-to-point connection between LANs. It is the most secure connection however the most expensive connectivity. Point to point connection.
- Circuit-Switched: Use the phone company as the service provider. A dedicated circuit path is created between the sender and receiver for the duration of the call. This is less expensive than a leased line, however is slow connection. There are two types of circuit-switched connections available: asynchronous and ISDN (Integrated Services Digital Network).
- Packet-Switched: Allows connection to the providers network. Devices transport packets by a shared single point-to-point or point-to-multipoint link across a carrier internetwork. Packets are transmitted over PVC or SVC. Since the data travels through a shared link, traffic is affected by other customers but the cost tends to be lower than the same bandwidth used for a dedicated line. Usually use Frame Relay.
- Cell-Switched: Similar to packet switching, but uses fixed length cells. Allows heavy traffic loads to be sent more efficiently. Data is transported across virtual circuits. This is best for simultaneous use of voice and data.
There are many different types of protocols used depending on location, type of WAN, and administrator knowledge.
- Point-to-Point Protocol (PPP)
- Serial Line Internet Protocol (SLIP)
- High-Level Data Link Control (HDLC)
- Frame Relay (FR)
- X.25
