A2 ICT..Networks



Factors which influence the choice of a network...

Factors which influence choice of a network include:

- Cost of network

- Size of organisation

- How the system will be used

- Existing systems

- Performance required

- Security issues

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Costs associated with a network

Costs associated with a network include:

- Network maintenance costs (upgrades, adding terminals)

- Staffing costs (network managers, technicians)

- Training costs

- Hardware costs (cabling, file servers, routers)

- System software costs (network operating system, network managment software)

- Cost of third party communication lines (BT, Virgin)

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Cost of network

Cost of network

This can include:

- Cost of cabling

- Costs of server

-  Costs of software

- Costs of third party communication services

Cost is a limiting factor with any network, for larger organisations cost is not normally a factor but with smaller organisations one major cost is the cost of someone who is able to manage thes ystem and deal with any problems in order to keep the network running.

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Size of organisation

Size of organisation

This determines the complexity of the network, larger organisations may have users in many sites all around the world, so communication costs can be high because the satellite links may have to be used.

The size of the organisation will also determine whether LAN or WAN is needed. Large networks need complex security measures and a range of specialist staff are needed to keep the network running.

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How the system will be used

How the system will be used

This will affect the scale of the network. Large retailers will need local area networks set up in each store with each store with each one being connected to form a wide area network. This will allow each store to perform local processing but still allow data communication with the head office. Some networks may allow employees to work from home using on-line databases, video conferencing and much, much more.

Some tasks such as order processing or booking tickets are performed interactivley by conducting a dialogue with the user. Networks used in this way need to be fast in order to reduce the response time. Some tasks such as payroll or the production of utility or credit card bills use batch processing, which means that all the inputs are collected together over a period of and then processed in one go. Batch processing requires lots of processing power and this will slow the network down for other users, so it is best to perform batch processing when other users arent using the system, for example less busy periods, ie nightime.

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Existing systems

Existing systems

When networks are introduced or exapnded, they often have to work with the exsisting systems. Often the new or exapnded network will need to work with the exsisting hardware and software and this is because staff understand the systems, you are not introducing too many new things from them to learn. It also keeps the costs down if some of the exsisting systems can be re-used.

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Performance required

Performance required

This will determine the way that the computers nd other hardware should be connected together (ie, the topology used) The performance needed will also determine thr type of server needed. Performance is also measured by how well the network supports the users; use of online help can ease with which users can get their work done using the user interface is a measure of performance.

E-Commerce systems will need to be fast otherwise users will get fed up waiting and choose to go elsewhere. It is essential that the network is realiable and available to all users at all times, so relaibility is also a performance issue.

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Mesures of network performance

Measures of network performance include:

- Reliability

- Speed

- Cost

- Usability

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Security issues

Security issues

Most networks offer a way of allowing users to access the internet. In many organisations the Internet is an essential part of the network, so steps need to be taken to keep hackers out and make sure that customer finanical details are not intercepted or revealed. If personal data is held, then appropriate security methods need to be in place to prevent unauthorised access. Other issues include the introduction of viruses, users copying copyrighted material using their computers, sending offensive e-mails and so on.

Security requirements of one organisation will be different from another. For example, a school worried about their pupils accessing certain sites or using chat rooms, whereas businesses will be more worried about making secure payments.

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Security issues continued

 Here are some security issues which need to be considered when choosing a network...

- Access to illicit material (eg, ***********, sites promoting racial hatred, etc)

- Whether users are free to use unlimited words in search engines or not.

- How hackers can be kepts out (eg, firewalls)

- How payment details can be kept secure (eg, encryption)

- Problems when users connect to networks wirelessly

- The need to avoid viruses

- The need to restrict staff access to only certain files

- The blocking of downloading copyright materials (eg, films, music, games)

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Exam tips

Exam tips

Many of the examination quesions on networks give a brief context to the question. Your answers must refer to this context and not simply the topic in general. For example, if the question is referring to a network being used by school pupils, you would not talk about the need for encryption to secure credit card payments made over the network...


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