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'''WAN''' or '''Wide Area Network''' is a data communications network in which computers, separated by a distance of more than half a mile, can be connected.<ref>[http://www.google.com.pk/search?hl=en&biw=1366&bih=667&q=wide+area+network&tbs=dfn:1&tbo=u&sa=X&ei=sVt_TrCvFI7z-gb_np2SDQ&ved=0CC4QkQ4 Google Dictionary]</ref> A WAN can consist of several [[LAN|Local Area Networks]] (LANs) or [[MAN|Metro Area Networks]] (MANs). The largest WAN in existence is the Inetrnet itself.<ref>[http://compnetworking.about.com/cs/lanvlanwan/g/bldef_wan.htm ComputerNetworking at About.com]</ref> 

Generally WANs are built by collaboration of different corporations, banks, military or [[ISP]]s. Local stores or corporations may use a WAN to connect with their customers. WANs are an effective way of communication between companies, or within a single company's own divisions and locations.<ref>[http://www.wisegeek.com/what-is-a-wide-area-network.htm WiseGeek]</ref> 

==Structure==
A WAN may seem like a bigger version of [[LAN]] but in reality its structure is quite different. Two LANs must exist in order to create a WAN. The WANs built by [[ISP]]s provide connectivity from LAN to Internet. WANs do not directly connect one computer to another, which is the role of a [[LAN]].<ref>[http://www.makeuseof.com/tag/technology-explained-wide-area-network-wan-tutorial/ MakeUseOf]</ref> Local Area Networks are connected by a device named router which then connects them to WAN.<ref>[http://compnetworking.about.com/od/basicnetworkingconcepts/a/network_types.htm ComputerNetworking at About.com]</ref> In a WAN, the data transmission is generally provided by telephone lines; however, it can also be connected through [[Packet Switching]], Circuit Switching, Cell Relay or leased lines.<ref>[http://www.wisegeek.com/what-is-a-wide-area-network.htm WiseGeek]</ref><ref>[http://www.makeuseof.com/tag/technology-explained-wide-area-network-wan-tutorial/ MakeUseOf]</ref> The main features of each connectivity option are:

'''Leased lines''' provide Point-to-Point connection between Local Area Networks.

'''Circuit switching''' creates a dedicated circuit path between end points as used in Dial-Up connections.

'''Packet switching''' creates packets of data which are then transferred through different variable length virtual circuits.

'''Cell relay''' also creates packets but these packets are tranferred through fixed length virtual circuits.<ref>[http://www.answers.com/topic/wide-area-network Answers]</ref>

==Technologies==
Several technologies and protocols can be used in WAN deployment, including:<ref>[http://docwiki.cisco.com/wiki/Internetworking_Technology_Handbook#WAN_Technologies CISCO DocWiki]</ref><ref>[http://compnetworking.about.com/cs/lanvlanwan/g/bldef_wan.htm ComputerNetworking at About.com]</ref>
* Frame Relay
* High-Speed Serial Interface
* Integrated Services Digital Network
* Point-to-Point Protocol
* Switched Multimegabit Data Service
* Synchronous Data Link Control and Derivatives
* X.25
* Digital Subscriber Line
* Sonet
* ATM

==References==
{{reflist}}

[[Category:Glossary|WAN]]