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, local area networks, campus area networks, or metropolitan area
networks which are usually limited to a room, building, campus or specific metropolitan
area 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 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
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 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 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. See also
References
External links Cisco - Introduction to WAN Technologies