A Wide Area Network (WAN) is a network that covers a broad area (i.e., any telecommunications network that links across metropolitan, regional, or national boundaries) using private or public network transports. Business and government entities utilize WANs to relay data among employees, clients, buyers, and suppliers from various geographical locations. In essence, this mode of telecommunication allows a business to effectively carry out its daily function regardless of location. The Internet can be considered a WAN as well, and is used by businesses, governments, organizations, and individuals for almost any purpose imaginable.
Related terms for other types of networks are personal area networks (PANs), local area networks (LANs), campus area networks (CANs), or metropolitan area networks (MANs) which are usually limited to a room, building, campus or specific metropolitan area (e.g., a city) respectively.
Design options 
The textbook definition of a WAN is a computer network spanning regions, countries, or even the world. However, in terms of the application of computer networking protocols and concepts, it may be best to view WANs as computer networking technologies used to transmit data over long distances, and between different LANs, MANs and other localised computer networking architectures. This distinction stems from the fact that common LAN technologies operating at Layer 1/2 (such as the forms of Ethernet or Wifi) are often geared towards physically localised networks, and thus cannot transmit data over tens, hundreds or even thousands of miles or kilometres.
WANs necessarily do not just connect physically disparate LANs. A CAN, for example, may have a localised backbone of a WAN technology, which connects different LANs within a campus. This could be to facilitate higher bandwidth applications, or provide better functionality for users in the CAN.
WANs are used to connect LANs and other types of networks together, so that users and computers in one location can communicate with users and computers in other locations. Many WANs are built for one particular organization and are private. Others, built by Internet service providers, provide connections from an organization's LAN to the Internet. WANs are often built using leased lines. At each end of the leased line, a router connects the LAN on one side with a second router within the LAN on the other. Leased lines can be very expensive. Instead of using leased lines, WANs can also be built using less costly circuit switching or packet switching methods. Network protocols including TCP/IP deliver transport and addressing functions. Protocols including Packet over SONET/SDH, MPLS, ATM and Frame relay are often used by service providers to deliver the links that are used in WANs. X.25 was an important early WAN protocol, and is often considered to be the "grandfather" of Frame Relay as many of the underlying protocols and functions of X.25 are still in use today (with upgrades) by Frame Relay.
Academic research into wide area networks can be broken down into three areas: mathematical models, network emulation and network simulation.
Performance improvements are sometimes delivered via wide area file services or WAN optimization.
Connection technology options 
Several options are available for WAN connectivity:
||Sample protocols used
||Point-to-Point connection between two computers or Local Area Networks (LANs)
||PPP, HDLC, SDLC, HNAS
||A dedicated circuit path is created between end points. Best example is dialup connections
||28 - 144 kbit/s
||Devices transport packets via a shared single point-to-point or point-to-multipoint link across a carrier internetwork. Variable length packets are transmitted over Permanent Virtual Circuits (PVC) or Switched Virtual Circuits (SVC)
||Shared media across link
||Similar to packet switching, but uses fixed length cells instead of variable length packets. Data is divided into fixed-length cells and then transported across virtual circuits
||Best for simultaneous use of voice and data
||Overhead can be considerable
Transmission rates usually range from 1200 bit/s to 24 Mbit/s, although some connections such as ATM and Leased lines can reach speeds greater than 156 Mbit/s. Typical communication links used in WANs are telephone lines, microwave links & satellite channels.
Recently with the proliferation of low cost of Internet connectivity many companies and organizations have turned to VPN to interconnect their networks, creating a WAN in that way. Companies such as Citrix, Cisco, New Edge Networks and Check Point offer solutions to create VPN networks.
National area network 
Some countries have nationwide computer networks, such as Kwangmyong in North Korea.
See also 
- ^ Groth, David and Skandler, Toby (2009). Network+ Study Guide, Fourth Edition. Sybex, Inc. ISBN 0-7821-4406-3.
- ^ McQuerry, Steve (November 19, 2003). 'CCNA Self-Study: Interconnecting Cisco Network Devices (ICND), Second Edition'. Cisco Press. ISBN 1-58705-142-7.
External links 
Computer Networking Tutorial - 4 - WAN
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CCNA - Wide Area Networks
For the Free Full Version visit http://www.nhanced.co.uk/free An introduction to Wide Area Networks, the backbone to passing your CCNA exam.
Packet Switched WAN Technologies - CompTIA Network+ N10-004: 2.5
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IT Trends & Analysis (IT-TNA)
Wed, 24 Apr 2013 21:41:55 -0700
Silver Peak has a suggestion: how about taking a look at the world's fastest wide area network optimization hardware appliance? The newest offering from the maker of physical and virtual WANop appliances is capable of delivering 20 Gbps of data ...
Marketwire (press release)
Mon, 29 Apr 2013 05:33:19 -0700
XO Communications Honored for Delivering Managed Wide Area Network Solution to U.S. Postal Service. U.S. Postal Service Recognizes XO Communications for Supplier Performance Excellence. HERNDON, VA--(Marketwired - Apr 29, 2013) - XO ...
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Before you can do much, you'll have to enable QoS (by selecting the Enable radio button) and fill in a few settings: WAN, LAN or both: Generally you'll use QoS to handle traffic from outside your local network, so you'll defaults to WAN (Wide Area ...
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The introduction of built-in wide area network acceleration and backup snapshots for Hewlett-Packard virtual storage appliances -- both of which will be available as part of Veeam Backup & Replication v7 Enterprise Plus Edition beginning in July ...
Marketwire (press release)
Wed, 15 May 2013 08:03:42 -0700
... telecommunications intelligence provider (TIP), today announced that its Radio Access Network Solutions was named a finalist in the Network Infrastructure - Wide Area Network category of CTIA's annual Emerging Technology (E-Tech) Awards competition.
Aviation Today (subscription)
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Park Air's system enables both voice and remote control data exchange over the implemented IP wide area network, in accordance with the international ED-137 standard, the global standard for voice over internet protocol for air traffic management ...
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The Leading Aviation Industry Resource for News, Equipment and
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“ARINC's AviNet supports any operation within an airport requiring wide-area network access, including both mission-critical as well as back-office applications,” said Alexis Hickox, Senior Director, Aviation Solutions ARINC EMEA. “We believe the ...
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