Wide Area Network (WAN)
A WAN is defined as a network that connects computers spread across a large geographical area. WAN may spread across a country, a continent, or the Earth. In practice, WAN are essentially an interconnection of Local Area Network (LAN) and therefore, WAN extend the benefits offered by LAN across large area. For example an organisation have three offices in New Delhi, Tokyo and Shanghai. If a LAN is set up in New Delhi, only the computers in the New Delhi office can share the data and resources. However, by setting up LAN in all the three locations, and interconnecting these LAN, the data and resources can be shared among all three locations. This ability to share data over vast geographical areas in the most important benefit of WAN as illustrated by the Internet. Internet is a WAN that is spread across the Earth.
Because of the huge difference in the geographical areas covered by LAN and WAN, the characteristics and implementations of LAN and WAN differ greatly.
The following are some of the important differences between LAN and WAN technologies:
Ownership: LAN are generally owned, and individuals or large organisations. The sheer size of WAN make it impossible for single person or a small organisation to maintain it.
Connectivity: The devices in a LAN are connected using coaxial cables, twisted pair cables, or optical fiber cables. However, to connect devices, and computers in WAN, connectivity options such as POTS, leased lines, ISDN, VSAT, Microwave and Infrared, are used. Although the connectivity options used in WAN may, in turn, include coaxial, twisted pair, or optical fiber cables, the technology used to establish the connection is different.
Hardware: In addition to cables, the hardware devices used to establish connection in WAN are different from those used in LAN. For example, computers in a LAN are connected by devices such as hubs, switches, and repeaters whereas devices such as routers, bridges and gateways are used to establish connectivity in a WAN.
Protocols: Computers in a LAN communicate among themselves using protocols such as Ethernet, Token Ring, or FDDI. Computers in a WAN use protocols such as Frame Relay, ATM, X.25 for communication.
Speed: The speed of data transfer is high in case of LAN. For example, Ethernet can transfer data at the rate of 10 Mbps. However, devices in a WAN communicate at relatively lower speeds, such as 1.544 Mbps in case of leased lines because of the distance involved and technologies used between the locations.
The following are some of the important differences between LAN and WAN technologies:
Ownership: LAN are generally owned, and individuals or large organisations. The sheer size of WAN make it impossible for single person or a small organisation to maintain it.
Connectivity: The devices in a LAN are connected using coaxial cables, twisted pair cables, or optical fiber cables. However, to connect devices, and computers in WAN, connectivity options such as POTS, leased lines, ISDN, VSAT, Microwave and Infrared, are used. Although the connectivity options used in WAN may, in turn, include coaxial, twisted pair, or optical fiber cables, the technology used to establish the connection is different.
Hardware: In addition to cables, the hardware devices used to establish connection in WAN are different from those used in LAN. For example, computers in a LAN are connected by devices such as hubs, switches, and repeaters whereas devices such as routers, bridges and gateways are used to establish connectivity in a WAN.
Protocols: Computers in a LAN communicate among themselves using protocols such as Ethernet, Token Ring, or FDDI. Computers in a WAN use protocols such as Frame Relay, ATM, X.25 for communication.
Speed: The speed of data transfer is high in case of LAN. For example, Ethernet can transfer data at the rate of 10 Mbps. However, devices in a WAN communicate at relatively lower speeds, such as 1.544 Mbps in case of leased lines because of the distance involved and technologies used between the locations.
** LAN and WAN were first differentiated on the basis of geographical span and ownership. Nowadays, however, LAN are used to connect computers that are spread across a considerable geographical area, for example a vast college campus. Also multiple organisations may connect their computers in a single network for business purposes. Therefore, the definitions of LAN and WAN overlap in spite of the factors discussed in this part.
WAN Connectivity Options
The term connectivity options collectively refer to the communication medium used to establish a connection between two LAN as well as the technology used by the medium to transmit data. In LAN, the connectivity is owned by the organisation that sets up the LAN. For example, the cables used to connect computers in a LAN are purchased by the organisation.
In case of WAN, the cost of the connectivity is high. Imagine, for example, an organisation having LAN in New Delhi, and Tokyo. The cost required to purchase the appropriate type of cables to connect these LAN would be expensive. So, connectivity in WAN is not owned by the organisation but obtained from service providers for a fee, known as access charges. The access charges typically depend on the following factors:
In additional to being expensive, the connectivity options in WAN are different from those used in LAN because WAN spread across a vast geographical area. In the previous example, to connect LAN in New Delhi and Tokyo, it is not possible to establish a connection using coaxial or twisted pair cables because of the distance between the two LAN.
The following are some of the popular connectivity options used to set up a WAN:
In case of WAN, the cost of the connectivity is high. Imagine, for example, an organisation having LAN in New Delhi, and Tokyo. The cost required to purchase the appropriate type of cables to connect these LAN would be expensive. So, connectivity in WAN is not owned by the organisation but obtained from service providers for a fee, known as access charges. The access charges typically depend on the following factors:
- Bandwidth required | Data transfer rate
- Type of connectivity ( for example: leased lines, switched circuits or ISDN)
- Distance between the locations to be connected (for example, a leased line connection between New Delhi, and Tokyo would cost more than one between New Delhi and New Yark)
- WAN Protocols
- Additional services offered by the service provider, such as security mentioned in the Service Level Agreements (SLA)
In additional to being expensive, the connectivity options in WAN are different from those used in LAN because WAN spread across a vast geographical area. In the previous example, to connect LAN in New Delhi and Tokyo, it is not possible to establish a connection using coaxial or twisted pair cables because of the distance between the two LAN.
The following are some of the popular connectivity options used to set up a WAN:
- Leased Lines: Leased line are also known as dedicated lines. Leased lines are dedicated point-to-point circuits provided by a telecommunications carrier for a fee.
- POTS: A Plain Old/Ordinary Telephone System is an analog technology that provides data transfer rates up to 33.6 Kbps.
- ISDN: Integrated Service Digital Network(ISDN) is a set of standard specified by International Telecommunication Union (ITU) for digital transmission over ordinary telephone copper wire as well as other media.
- VSAT: Very Small Aperture Terminal (VSAT) is a technology used to connect computers, or networks that are located in geographically remote locations where terrestrial connectivity options are not available or not reliable. In VSAT, the computers or networks that are connected communicate with the help of a satellite.
- Microwave: It is a wireless technology that can be used to transmit digital information between two computers that can be around 15 kilometers apart. It is possible to use repeaters amplifiers, to boost the signal strength so that computers as far as 40 kilometers, or more, apart can communicate.
- Radio: In this methods, radio waves are used to wirelessly connect LAN, or computers. The computers, or networks that need to communicate using radio waves should have an antenna.
- Infrared: Infrared technology allows devices with infrared ports to communicate with each other, and share data. Infrared transports data through light, which is invisible to a human eye. The infrared light is usually in the frequency range of 1000 GHz.
** POTS, leased lines, and ISDN are terrestrial connectivity options because they use a physical medium, such as phone lines, over land to establish connectivity. On the contrary, VSAT, Microwave, Infrared and Radio are wireless connectivity options.
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What is WAN | WAN Connectivity Options
Reviewed by Neel Kamal
on
September 16, 2018
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Reviewed by Neel Kamal
on
September 16, 2018
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Very useful
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