The Computer Revolution/Networks/WAN

Wide Area Network
WAN is the computer network that covers a large geographical area, which usually consists of two or more smaller networks called LANs. The LAN network is the public network and it could run through the telephone lines or through satelites. Our personal computers are connected to the LAN network. The internet is the WAN network which is the largest network. The LAN networks could be public or privately owned. There are few WAN technologies used:
 * point-to-point links - point to point links connects the customer's premise to the main network through a telephone circuit.Usually these connections are more expensive than the shared networks.
 * circuit switching - the data communication is initiated when is needed and is disconnected when is not needed. It is similar to a voice service. Some wireless devices work on the ISDN network, which is usually faster and more reliable. ISDN is an example of circuit switching.
 * packet switching - here customers share the carrier's network. The cost is usually cheaper for the customer and allows the carrier to use the network more efficiently.
 * WAN virtual circuits - this is a shared network between two other networks
 * WAN dial-up services - it is a very cheap way of initializing the network. Here the customer uses a telephone line to connect to the internet using on demand routing.
 * WAN devices - there are switches, access servers, modems, ISDN adapters, routers and ATM switches.