Local & Wide Area Networks

Networks• A network is two or more computers linked

together• Networks are used to share programs, data

and resources.• There are two main types of network

• LAN (Local Area Network)• WAN (Wide Area Network)

• Computers on a network are called stations.• One station on the network is a powerful

computer called a file server.

Local Area Network (LAN)

• covers a small area such as a room, building and is usually owned by an individual, company or small organisation

• Is a fast network• Is connected by its own wiring

Advantages of LAN’s

• Share data and programs between stations

• Share resources, e.g. peripherals such as printers, scanners.

• Sharing makes it cheaper • Use e-mail service

Advantages of LAN’s

• Keep data secure using passwords• Reduce unauthorised access using

different level of access (read-only)• Allow users to access their files from

any computer on the network • Allow users to work on the same files

at the same time (multi access)

LAN Transmission Media

• copper wire• fibre optic (glass)• infrared• bluetooth • WiFi

WAN (Wide Area Networks)

A network that covers a large geographical area such as a country or the whole world!!

The Internet is one example

Advantages of WAN’s

• Same as LAN’s except you do not usually share peripherals

• Send e-mail worldwide• Video conferencing• Voice over data (Free phone calls

worldwide)

WAN Transmission Media

Any communication carried over a long distance is called telecommunication.

A WAN uses the telephone system which includes:• Copper cables• Microwave transmission links• Satellite links• Optical fibres links

Network SecurityData can be lost through • accidents • system failures• deliberate action (unauthorised access)

There are two ways of securing data:• physical security• electronic security

Physical Security• locks on rooms

• identity cards (Magnetic stripe or Smart card)

• biometrics - fingerprint, iris scan or voice print

• stand-alone computer

Electronic Security

• Passwords• Levels of access• Encryption (putting into code)

• Very important in wireless networks

Absolute Security

"Three may keep a secret if two of them are dead" Ben Franklin

NO NETWORK!!

Client & Server NetworkServer• A computer that delivers data and

software to other computers (clients) linked by a network.

• Usually has• Fast processor• Large memory• Large hard disc

Types of servers

• File• Mail• CD• Internet

File ServerA file server stores

• programs • data • list of all users allowed access to the network

(authorised users)

• Once you have logged-on the file server allows you access to the network (on-line)

• Logging–on: identifies a user to the file server ( usually by entering username & password)

Network Interface Card (NIC)

• This is a small circuit board that allows the computer to communicate with a computer network.

• Some computers have a wireless network interface card that allows them to communicate with a nearby LAN

Social, Legal & Ethical Issues

Social Issues

Teleworking

This is the process of • working from home and • using a computer • to connect to a wide area network • to communicate with the office.

There are several advantages to employees and employers:

Advantages of Teleworking

Advantages to employees:• Choose own working hours• Save money on fuel, child care costs• Reduce congestion on the roads, pollution

and travelling time

Advantages to employers:• Do not have to provide premises, heating

lighting, rent, rates.

Disadvantages of Teleworking

Disadvantages to Employees:• May not be given same rights to health

& safety (electrical faults)• Workers may become isolated or lonely

Disadvantages to Employers• Must ensure all electrical equipment

complies with health & safety issues• Must take responsibility for ‘information

security’ of remote workers

Social Benefits of WANAdvantages:• Improve communication in isolated areas &

reduce isolation• Allow people to keep in contact with family

abroad via e-mail & websites• People connected to the Internet have access

to a large pool of information (Information rich)

Disadvantages:• May increase social isolation as more people

go on-line (become detached from real world)• Costly – those not connected may be further

disadvantages (Information poor)

Legal Issues

Legal IssuesLaws which affect computers include:

• Computer Misuse Act

• The Data Protection Act

• The Copyright, Designs & Patents Act

• The Privacy and Electronic Communications Regulations 2003

Computer Misuse Act

• Unauthorised access (hacking)• Creating a virus

• A progam• that copies itself• that may cause harm

The Data Protection Act (1998)

This Act compels any company to take specific measures to ensure that all personal information held about living (identified or identifiable) individuals is processed according to eight Data Protection Principles

Data Protection Act Principles

Data users must• Obtain and process the data fairly and lawfully• Register the purpose for which they hold it• Use only for this purpose• Hold only adequate and relevant data• Keep data accurate and up-to-date• Not keep data longer than necessary• Give individuals access to their own data• Take appropriate security measures

Data Protection Act Exemptions

• Law Enforcement • National Security • Examination Marks and Examiners’

Comments • Adoption Records and Reports • Lawyer-client communications.

The Copyright, Designs and Patents Act (1988)

• “intellectual property”• “expression of an idea”• all computer software, whether covered by a specific licence or not, is copyrighted under this Act.

• the program itself• screen shots• associated documentation

Privacy and Electronic Communications Regulations

2003• This act makes it illegal for companies

to send you unsolicited e-mail (Junk Mail). Note: Unsolicited means something that you did not ask for.

• Companies must get permission from an individual before they can send them an e-mail or text

• An Individual must be given the choice of refusal

Ethical Issues

Ethical IssuesThese are concerned with people’s judgement as

to what is right or wrong.

Invasion of personal privacy• Is it acceptable for government bodies [NSA(US),

GCHQ(UK)] to intercept private data sent across networks to prevent terrorism & crime

Censorship & freedom of speech• Should anyone be able to set up a website even

though it is used to incite hatred & racism• Should the government be able to block these

web sites, e.g. bomb making

Local & Wide Area Networks

End of presentation