Transcript Local Area Networks

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
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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:
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Copper cables
Microwave transmission links
Satellite links
Optical fibres links
Network Security
Data 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 Network
Server
• 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
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File
Mail
CD
Internet
File Server
A 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
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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 WAN
Advantages:
• 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 Issues
Laws 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
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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 Issues
These 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