wide area network
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A wide area network (WAN) is a
telecommunications network A telecommunications network is a group of nodes interconnected by links that are used to exchange messages between the nodes. The links may use a variety of technologies based on the methodologies of circuit switching, message switching, or pac ...
that extends over a large geographic area for the primary purpose of
computer network A computer network is a group of computers that use a set of common communication protocols over digital signal, digital interconnections for the purpose of sharing resources located on or provided by the Node (networking), network nodes. The ...
ing. Wide area networks are often established with
leased telecommunication circuits A lease is a contractual arrangement calling for the wikt:lessee, lessee (user) to pay the Lessor (leasing), lessor (owner) for use of an asset. Property, buildings and vehicles are common assets that are leased. Industrial or business equipment i ...
. Businesses, as well as schools and government entities, use wide area networks to relay data to staff, students, clients, buyers and suppliers from various locations around the world. In essence, this mode of telecommunication allows a business to effectively carry out its daily function regardless of location. The
Internet The Internet (Capitalization of Internet, or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a ''network of networks'' t ...

Internet
may be considered a WAN.


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
communication protocol A communication protocol is a system of rules that allows two or more entities of a communications system to transmit information via any kind of variation of a physical quantity. The protocol defines the rules, syntax, semantics and synchronizat ...
s and concepts, it may be best to view WANs as computer networking technologies used to transmit data over long distances, and between different networks. This distinction stems from the fact that common
local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, school, laboratory, university campus or office building. By contrast, a wide area network (WAN) not only covers a larger ...
(LAN) technologies operating at lower layers of the
OSI model The Open Systems Interconnection model (OSI model) is a conceptual model that characterises and standardises the communication functions of a telecommunication or computing system without regard to its underlying internal structure and technolo ...

OSI model
(such as the forms of
Ethernet Ethernet () is a family of wired computer network A computer network is a group of computers that use a set of common communication protocols over digital signal, digital interconnections for the purpose of sharing resources located on or ...

Ethernet
or
Wi-Fi Wi-Fi () is a family of wireless network Communication protocol, protocols, based on the IEEE 802.11 family of standards, which are commonly used for Wireless LAN, local area networking of devices and Internet access, allowing nearby digital de ...

Wi-Fi
) are often designed for physically proximal networks, and thus cannot transmit data over tens, hundreds, or even thousands of miles or kilometres. 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 provider#REDIRECT Internet service provider {{Redirect category shell, 1= {{R from other capitalisation ...
s, provide connections from an organization's LAN to the Internet. WANs are often built using
leased line A leased line is a private telecommunications circuit between two or more locations provided according to a commercial contract. It is sometimes also known as a private circuit, and as a data line in the UK. Typically, leased lines are used by b ...
s. 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. Because leased lines can be very expensive, instead of using leased lines, WANs can also be built using less costly
circuit switching Circuit switching is a method of implementing a telecommunications network A telecommunications network is a group of nodes interconnected by links that are used to exchange messages between the nodes. The links may use a variety of technologi ...
or
packet switching In telecommunications, packet switching is a method of grouping Data (computing), data that is transmitted over a digital Telecommunications network, network into ''network packet, packets''. Packets are made of a header (computing), header and a p ...
methods. Network
protocols Protocol may refer to: Sociology and politics * Protocol (politics)Protocol originally (in Late Middle English, c. 15th century) meant the minute or logbook taken at a meeting, upon which an agreement was based. The term now commonly refers to an a ...
including
TCP/IP The Internet protocol suite is the conceptual model A conceptual model is a representation of a system, made of the composition of concept Concepts are defined as abstract ideas or general notions that occur in the mind, in speech, or in tho ...
deliver transport and addressing functions. Protocols including
Packet over SONET/SDH Packet over SONET/SDH, abbreviated POS, is a communications protocol for transmitting Packet (information technology), packets in the form of the Point to Point Protocol (PPP) over Synchronous optical networking, SDH or SONET, which are both stand ...
,
Multiprotocol Label Switching Multiprotocol Label Switching (MPLS) is a routing technique in telecommunications network A telecommunications network is a group of nodes interconnected by links that are used to exchange messages between the nodes. The links may use a variet ...

Multiprotocol Label Switching
(MPLS),
Asynchronous Transfer Mode Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by ANSI and ITU (formerly CCITT) for digital transmission of multiple types of traffic, including telephony (voice), data transmission, data, and video signals in one netwo ...
(ATM) and
Frame Relay#REDIRECT Frame Relay 350px, A basic Frame Relay network Frame Relay is a standardized wide area network (WAN) technology that specifies the Physical layer, physical and data link layers of digital telecommunications channels using a packet switc ...
are often used by service providers to deliver the links that are used in WANs. Academic research into wide area networks can be broken down into three areas:
mathematical model A mathematical model is a description of a system A system is a group of Interaction, interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environmen ...
s, network emulation, and network simulation. Performance improvements are sometimes delivered via wide area file services or
WAN optimization WAN optimization is a collection of techniques for improving data transfer across wide-area networks (WANs). In 2008, the WAN optimization market was estimated to be $1 billion, and was to grow to $4.4 billion by 2014 according to Gartner, a tec ...
.


Private networks

Of the approximately four billion addresses defined in IPv4, about 18 million addresses in three ranges are reserved for use in
private network In IP network The Internet protocol suite is the Conceptual model (computer science), conceptual model and set of communications protocols used in the Internet and similar computer networks. It is commonly known as TCP/IP because the foundatio ...
s. Packets addressed in these ranges are not routable on the public Internet; they are ignored by all public routers. Therefore, private hosts cannot directly communicate with public networks, but require
network address translation#REDIRECT Network address translation Network address translation (NAT) is a method of mapping an IP address space In computing, an address space defines a range of discrete addresses, each of which may correspond to a network host, peripheral dev ...
at a routing gateway for this purpose.
:
Since two private networks, e.g., two branch offices, cannot directly communicate via the public Internet, the two networks must be bridged across the Internet via a
virtual private network The term virtual private network (abbreviated VPN) describes any technology that can encapsulate and transmit network data, typically Internet Protocol data, over another network. Such a system enables users to access network resources that may ...
(VPN) or other form of
IP tunnel {{No footnotes, date=March 2021 An IP tunnel is an Internet Protocol (IP) network communications channel between two networks. It is used to transport another network protocol by Encapsulation (networking), encapsulation of its packet (information ...
that encapsulates packets, including their headers containing the private addresses, for transmission across the public network. Additionally, encapsulated packets may be encrypted to secure their data.


Connection technology

Many technologies are available for wide area network links. Examples include
circuit-switched Circuit switching is a method of implementing a telecommunications network A telecommunications network is a group of nodes interconnected by links that are used to exchange messages between the nodes. The links may use a variety of technologi ...
telephone lines,
radio wave Radio waves are a type of electromagnetic radiation In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies ma ...
transmission, and
optical fiber An optical fiber (or fibre in British English) is a flexible, transparency and translucency, transparent fiber made by Drawing (manufacturing), drawing glass (silica) or plastic to a diameter slightly thicker than that of a Hair's breadth, hu ...

optical fiber
. New developments have successively increased transmission rates. In ca. 1960, a line was normal on the edge of the WAN, while core links of 56 or 64 kbit/s were considered fast. Today, households are connected to the Internet with
dial-up Dial-up Internet access is a form of Internet access Internet access is the ability of individuals and organizations to connect to the Internet using computer terminals, computers, and other devices; and to access services such as email and the H ...
,
asymmetric digital subscriber line Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telec ...
(ADSL),
cable Cable may refer to: Mechanical * Nautical cable A nautical cable is a band of tightly woven and clamped ropes, of a defined cable length, used during the age of sail for deep water anchoring, heavy lifting, ship to ship transfers and towing durin ...
,
WiMAX Worldwide Interoperability for Microwave Access (WiMAX) is a family of wireless broadband Wireless broadband is telecommunications technology that provides high-speed wireless Wireless communication (or just wireless, when the context all ...
,
cellular network A cellular network or mobile network is a communication network A telecommunications network is a group of nodes In general, a node is a localized swelling (a "knot") or a point of intersection (a Vertex (graph theory), vertex). Node may ref ...
or
fiber Fiber or fibre (from la, fibra, links=no) is a #Natural fibers, natural or #Man-made fibers, man-made substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineer ...
. The speeds that people can currently use range from 28.8 kbit/s through a 28K
modem A modulator-demodulator, or simply a modem, is a hardware device that converts data from a digital format, intended for communication directly between devices with specialized wiring, into one suitable for a transmission medium such as telep ...

modem
over a telephone connection to speeds as high as 100 Gbit/s using 100 Gigabit Ethernet. The following communication and networking technologies have been used to implement WANs. *
Asynchronous Transfer Mode Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by ANSI and ITU (formerly CCITT) for digital transmission of multiple types of traffic, including telephony (voice), data transmission, data, and video signals in one netwo ...
*
Cable modem A cable modem is a type of network bridge A network bridge is a Networking hardware, computer networking device that creates a single, aggregate network from multiple communication networks or network segments. This function is called netwo ...
*
Dial-up internet Dial-up Internet access is a form of Internet access that uses the facilities of the public switched telephone network (PSTN) to establish a connection to an Internet service provider (ISP) by dialing a telephone number on a conventional telephone ...
*
Digital subscriber line Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data Digital usually refers to something using digits, particularly binary digits. Technology and computing Hardwa ...
*
Fiber-optic communication Image:Optical-fibre-junction-box.jpg, An optical fiber patching cabinet. The yellow cables are Single-mode optical fiber, single mode fibers; the orange and blue cables are Multi-mode optical fiber, multi-mode fibers: 62.5/125 μm OM1 and 50 ...
*
Frame Relay#REDIRECT Frame Relay 350px, A basic Frame Relay network Frame Relay is a standardized wide area network (WAN) technology that specifies the Physical layer, physical and data link layers of digital telecommunications channels using a packet switc ...
*
ISDN Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital Digital usually refers to something using digits, particularly binary digits. Technology and computing Hardware *Digital electronics Di ...
*
Leased line A leased line is a private telecommunications circuit between two or more locations provided according to a commercial contract. It is sometimes also known as a private circuit, and as a data line in the UK. Typically, leased lines are used by b ...
*
SD-WAN SD-WAN is an acronym for software-defined networking (SDN) in a wide area network (WAN). SD-WAN simplifies the management and operation of a WAN by decoupling the networking hardware from its control mechanism. This concept is similar to how sof ...
*
Synchronous optical networking Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are standardized protocols that transfer multiple digital bit stream A bitstream (or bit stream), also known as binary sequence, is a sequence of bits. A bytestrea ...
*
X.25 X.25 is an ITU-T The ITU Telecommunication Standardization Sector (ITU-T) coordinates standards for telecommunications and Information Communication Technology such as X.509 for cybersecurity, Y.3172 and Y.3173 for machine learning, and H.264/MPE ...
AT&T conducted trials in 2017 for business use of
400-gigabit Ethernet Terabit Ethernet or TbE is Ethernet Ethernet () is a family of wired computer network A computer network is a group of computers that use a set of common communication protocols over digital signal, digital interconnections for the purp ...
. Researchers Robert Maher, Alex Alvarado, Domaniç Lavery, and Polina Bayvel of
University College London , mottoeng = Let all come who by merit deserve the most reward , established = , type = Public university , public research university , endowment = £143 million (2020) , budget = £1.544 billion (2019/20) , chancellor = HRH Anne, Princes ...
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 potentially quadruples transfer speeds with fiber optics.


See also

*
Cell relay In computer network A computer network is a group of computers that use a set of common communication protocols over digital signal, digital interconnections for the purpose of sharing resources located on or provided by the Node (networking), ...
*
Internet area network An Internet area network (IAN) is a concept for a communications network that connects voice and data endpoints within a cloud environment over IP, replacing an existing local area network (LAN), wide area network (WAN) or the public switched t ...
(IAN) * Label switching *LPWAN, Low power wide area network (LPWAN) *Wide area application services *Wide area file services *Wireless WAN


References


External links


Cisco - Introduction to WAN Technologies
*
What is a software-defined wide area network?
{{DEFAULTSORT:Wide Area Network Wide area networks Telecommunications Data transmission