Wide Area Networks (WAN):
Definition and Explanation:
A wide area network (WAN) is a communication network that
covers a wide geographical area such as a state, country, or even world.
Types of Wide Area Networks:
a. Intranet/Extranet/ Metropolitan Area
Network/Geographical Area Network (MAN/GAN)
b. Value Added Networks (VAN)
c. Internet
| Types of Network |
Example |
| Network of networks |
The Internet |
| Wide area network (WAN) |
The phone system |
| Metropolitan area network (MAN) |
A campus/city network |
| Local area network (LAN) |
PC network within a building |
a. Intranet/Extranet/ Metropolitan Area
Network/Geographical Area Network (MAN/GAN):
The company's own wide area networks for limited users is
known as intranet. The idea behind an Intranet, is that companies setup their
own mini version of Internet, using a combination of the company's own networked
computers and Internet technology. Potential applications include daily company
newspapers, introduction material, online procedures and policies manuals,
employees web pages where individuals post up details of their activities and
progress, and internal database of the corporate information store.
An Intranet is an Internet organizational Internet that is
guarded against outside access by physical security software. The special
security software that protects against outside access is called firewall.
Private Intranet that are extended to users outside the company are extranets.
Extranets are especially useful for linking organizations with customers or
business partners. They often are used for providing product availability,
pricing, and shipment data, and electronic data interchange.
The Benefits of Intranet:
A considerable amount of money can be saved from the
elimination of storage, printing, and distribution of documents that can be
available to employees online.
Documents online are more widely used than those that are kept
on shelves, especially if the document is bulky and need to be searched. This
means that there are improvements in productivity and efficiency.
Wider access to corporate information should open the way to
more flexible working patterns. For instance, if bulky reference materials are
available online then there is a little need to be in office at all.
b. Value Added Network (VAN):
A Value Added Network (VAN) provides a range of services to its customers. The
network vendor generally leases lines from a common carrier and adds
services or value to the leased lines.
A Value Added Network (VAN) is a semipublic network that provides additional
services beyond the simple communication of information from one place to
another. Similar to a public network, a VAN is owned and operated by a
communications service provider and used by many organization. A VAN operates at
a greater speed than public network, and offer high security.
Value added is the most important aspect of a VAN. For
example, if your organization needs EDI capabilities with various suppliers and
customers around the world, you can choose to create your own network by
purchasing all the necessary network hardware and software, leasing private
lines from various communications services providers, and devolving the software
for handling the necessary conversions associated with the EDI transmission of
information. If you require this capability, then you've chosen to create a
private network.
However, your organization may find that this is simply
unfeasible; economically, technically, or otherwise. So you can chose to pay for
the services of a VAN. For example, you might chose to use communication service
provider's value-added network. Communication service provider places the
necessary communication media and software for handling the EDI transmission of
information. It's really just a simple matter of developing interfaces between:
- Your system and communication system provider's VAN
- Your costumes' and suppliers' system and communication system provider's VAN
Communication system provider take care of all the rest;
always assuring that you have communications capability among various countries
communication services providers (if you need international communication
capabilities), establishing mail boxes for EDI transmission, and so on.
c. Internet:
The Internet called "the mother of all networks", or simply
"the net," is an international network connecting approximately 140,000 smaller
networks in more than 200 countries. Educational, commercial, nonprofit,
government, and military entries from these networks. Each of the small
independent networks on the Internet makes its own decision about what resources
to make available on the Internet. There is no single authority that controls
the net overall.
Try as you may, you cannot imagine how much data is available
on the Internet. Besides e-mail, chat rooms, messages boards, games, and free
software, there are thousands of databases containing information of all sorts.
The Internet is growing faster than all other technologies the
have proceeded it. Radio existed for 38 years before it had50million listeners,
and television took 13 years to reach that number of viewers.
Difference Between LAN and WAN:
- A LAN is restricted to a limited geographical coverage of a few kilometers, but WAN spans greater distance and may operate nationwide or even worldwide.
- The cost to transmit data in LAN is negligible since the transmission medium is usually owned by the user organization. However, in case of WAN, this cost may be very high because the transmission mediums used are leased lines or public system such as telephone lines, microwave, and satellite links.
- In a LAN, the computers, terminals and peripheral devices are usually physical connected with wire and coaxial cables, whereas in WAN there may not be a direct physical connection between various computers.
- Data communication speed is much higher in LAN than in WAN.
Fewer data transmission error occur in case of a LAN as
compared to WAN. This mainly because in case of a LAN, the distance covered by
the data is negligible compared to WAN.
Advantages and Disadvantages of Distributed data Processing:
Computers are business tools, and they rapid development in
small computers have made them increasingly cost effective. Distributed data
processing is a management concept the tries to increase the usability of
computers by bringing them closer to the end user and by integrating them into
daily business activities at the locations at which these activities take place.
Advance in both computer and communications hardware and software are increasing
the feasibility of placing data processing power throughout all the departments
of locations of a business firm.
We define distributed data processing system as a
configuration in which many geographically dispersed or distributed independent
computer systems are connected by a telecommunications network, and in which
messages, processing tasks, programs, data, and other resources are transmitted
between cooperating processors and terminals. Such an arrangement enables the
sharing of many hardware and significant software resources among several users
who may be sitting far away from each other.
Advantages:
- A distributed data processing system attempts to capture the advantages of both centralized system. Each computer can be used to process data like a decentralized system. In addition, a computer at one location can also transfer data and processing jobs to and from computers at other locations.
- It allows greater flexibility in placing true computer power at the location where it is needed.
- Better computers resources are easily available to the end users.
- It facilitates quick and better access to data and information especially where distance is major factor.
- Network use can develop their own specialized applications with the help of skilled computer.
- The availability of multiple processors in the network permits peak load sharing and provides backup facilities in the event of equipment failure.
- User with access to nearby computer and databases may be able to react more rapidly.
Disadvantages:
- There are lack of proper security controls for protecting the confidentially and integrate of the user programs and that are stored online and transmitted over network channels.
- Due to lack of adequate computing/communications standard, it is not possible to link different equipment produced by different vendors into a smoothly functioning network. Thus several good resources may not be available to the user of network.
- Due to decentralization of resource at remote sites, management from central control point becomes very difficult. This normally result in increased complexity.
- System reliability, flexibility, response time, vendor support, and the cost of telecommunications facilities used, are some of the important factors that may disappoint network users in some cases.
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