Wide area network A wide area network is a network that covers
a broad area using leased telecommunication lines. 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 do not just necessarily 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:
Transmission rates have increased over time and will continue to increase. Around 1960
a 110 bit/s (bits per second) line was normal on the edge of the WAN, while core links of 56
kbit/s to 64 kbit/s were considered "fast". At this moment (2014) households are connected
to the Internet with ADSL or cable at speeds ranging from 1 Mbit/s to 100 Mbit/s and
the connections in the core of a WAN can range from 1 Gbit/s to 100 Gbit/s.
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.