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Management Information Systems

Notes Organisations supporting WAN using the Internet Protocol are known as Network Service
Providers (NSPs). These form the core of the Internet. By connecting the NSP and WAN together,
using links at Internet Packet Interchanges, a global communication infrastructure is formed.
NSPs do not generally handle individual customer accounts (except for the major corporate
customers), but instead deal with intermediate organisations whom they can charge for high
capacity communications. They generally have an agreement to exchange certain volumes of
data at a certain quality of service with other NSP. So practically any NSP can reach any other
NSP, but may require the use of one or more other NSP networks to reach the required destination.
NSPs vary in terms of the transit delay, transmission rate, and connectivity offered.
A WAN system is shown in the Figure 6.15 below. This connects a number of End Systems e.g.
A, C, H, K and a number of Intermediate Systems e.g. B, D, E, F, G, I, J to form a network over
which data may be communicated between the End Systems. The characteristics of the transmission
facilities lead to an emphasis on efficiency of communications techniques in the design of
WANs. Controlling the volume of traffic and avoiding excessive delays is important. Since the
topologies of WANs are likely to be more complex than those of LANs, routing algorithms also
receive more emphasis. Many WANs also implement sophisticated monitoring procedures to
account for which users consume the network resources. This is, in some cases, used to generate
billing information to charge individual users.

Figure 6.15: The Functioning of WAN

6.5.4 Value Added Network (VAN)

VAN is also an acronym for virtual area network. A Value-Added Network (VAN) is a private
network provider that is hired by a company to facilitate Electronic Data Interchange (EDI) or
provide other network services. VANs are public networks that add value by transmitting data
and by providing access to commercial databases and software. The use of VANs is usually sold
by subscription, with users paying for the amount of data they move. VANs are used for a
number of reasons. They can be considered as a way of transmitting computerized data, offering
a service similar to what the telephone networks do for telephone calls. VANs can send data
between computers in different cities or even different countries. They are often used in Electronic
Data Interchange (EDI) systems because they reduce the complexity of connecting to the disparate
EDI systems of various trading partners.
In this application they collect forms in an electronic mailbox, translate and forward them to
recipients, and guarantee they will reach their destinations intact. Other common VAN services
include electronic mail, access to stock market data and other public databases, and access to
electronic banking and other transaction processing services.
VANs are a cost-effective solution for companies that need data communication services but do
not want to invest in setting up their own private networks. In addition, companies that lack the

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