Wide Area Network (WAN)


Definition of Wide Area Network (WAN) in Network Encyclopedia.

What is a Wide Area Network (WAN)?

Wide Area Network, or WAN, is a geographically distributed network composed of local area networks (LANs) joined into a single large network using services provided by common carriers.

Wide Area Network (WAN) - Typical Schematic
Wide Area Network (WAN)
Typical Schematic

Wide area networks (WANS) are commonly implemented in enterprise networking environments in which company offices are in different cities, states, or countries or on different continents.

WAN technologies were previously limited to expensive leased lines such as T1 lines, slow packet-switching services such as X.25, cheap but low-bandwidth solutions such as modems, and dial-up Integrated Services Digital Network (ISDN) connections, but this has changed considerably in recent years. Frame relay services provide high-speed packet-switching services that offer more bandwidth than X.25, and virtual private networks (VPNs) created using Internet Protocol (IP) tunneling technologies enable companies to securely connect branch offices by using the Internet as a backbone service.

Intranets and extranets provide remote and mobile users with access to company resources and applications and provide connectivity with business partners and resellers. Wireless networking technologies allow roaming users to access network resources by using cell-based technologies. Digital Subscriber Line (DSL) services provide T1 speeds at much lower costs than dedicated T1 circuits. These and other new technologies continue to evolve and proliferate, allowing enterprise network administrators to implement and administer a highly diverse range of WAN solutions.

Wide Area Network examples

The best example of a Wide Area Network is th Internet itself. Other smaller examples of WANs are:

  • A network of bank cash dispensers;
  • A Company network with several branch offices geographically distant.
  • A school network is usually a LAN.
  • LANs are often connected to WANs, for example, a school network could be connected to the Internet.
  • WANs can be connected together using the Internet, leased lines or satellite links.
Wide Area Network - Connecting Headquarters to branch offices
Company Wide Area Network

Wide Area Networks disadvantages

  • WAN networks are much more expensive than home or corporate intranets.
  • WANs that cross international and other territorial boundaries fall under different legal jurisdictions. Disputes can arise between governments over ownership rights and network usage restrictions.
  • Global WANs require the use of undersea network cables to communicate across continents. Undersea cables are subject to sabotage and also unintentional breaks from ships and weather conditions. Compared to underground landlines, undersea cables tend to take much longer and cost much more to repair.

Very Fast Wide Area Network (400 Gbit Ethernet)

AT&T conducted trials in 2017 for business use of 400 gigabit Ethernet. Researchers Robert Maher, Alex Alvarado, Domaniç Lavery, and Polina Bayvel of University College London were able to increase networking speeds to 1.125 terabits per second. Christos Santis, graduate student Scott Steger, Amnon Yariv, Martin and Eileen Summerfield developed a new laser that quadruples transfer speeds with fiber optics.

If these two technologies were combined, then a transfer speed of up to 4.5 terabits per second could potentially be achieved.

Wide Area Network (WAN) explained in a video

Wide Area Network explained

Web References

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