Transcript Introduction_to_Networks

Introduction to
Networks
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This lesson will cover:
The purpose and uses of networks.
The key components of a computer network.
The different types of network and the
advantages and disadvantages of them.
Icons key:
For more detailed instructions, see the Getting Started presentation
Flash activity. These activities are not editable.
Teacher’s notes included in the Notes Page
Student task accompanies this slide
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Web addresses
Functional Skills check
Printable activity
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The importance of networks
Networking is a way of connecting hardware together so that
software, data, files and peripheral devices can be shared.
Networks
allow users to
have access to
lots of
hardware
devices from
their personal
terminal.
What other advantages do networks have?
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What is the Internet?
The Internet is a network of networks that connects
governments, people and companies all over the world.
10 Downing Street,
London, England
Koji Araki,
Japan
Sydney Opera
House, Australia
The Internet
Patel’s Fine Silks, India
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Jim’s
Skateboards
USA
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Where did it begin?
The Internet began in the 1980s
to allow US universities to share
computer resources. It grew so
much that by the 1990s it had
become possible for people to
use the Internet from home.
The World Wide Web (www) was developed to make
browsing (viewing) easier through http (Hypertext
Transfer Protocol).
http is a set of standards that
allows web browsers and
servers to communicate.
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Network components – modems
A modem stands for modulator–demodulator. They connect
computers to the Internet or distant networks by converting the
digital, binary signals into an analogue signal
that can be transmitted down telephone lines.
Old modems converted digital
information to an audio signal.
Press play to hear this.
Modern modems are built into computers
and use DSL or ADSL technology. These
use much higher transmission frequencies
which allows for faster data transfer.
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Network components – network cards
In order for a computer to function as part of a network, it
has to have a special piece of equipment installed to give it
this capability.
This is called a Network
Interface Card or NIC. It has
a port for a network cable to
be connected.
NICs are still very common,
but increasingly people are
using wireless network cards
or wireless USB adaptors.
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Ethernet and alternatives
Ethernet is the name given to the most common method of
networking computers. Although other methods exist,
Ethernet has been the standard since the 1990s.
Ethernet uses Cat5
cables to connect
computers together.
What alternatives are
there to Ethernet?
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Cables
There are many types of network cable.
Twisted-pair cables are the most common.
This cabling is often called ethernet cabling.
Category 5 (Cat5) twisted-pair cables can carry
100 Mb per second over distances of up to 100 metres.
Coaxial cable is better at resisting interference
and can be run for longer lengths, but it is not as
flexible and is not used much now.
Fibre optic cable can transfer data at higher
speeds over longer distances, and can be used outside
buildings, but it is much more expensive. It has a central core
made of glass and transmits the signals using light.
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Remember the terminology
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Hubs, switches and routers
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Wireless networks
With improvements in radio technology, it has become possible
to connect computers on a LAN network without using wires.
A wireless network card
is similar to a standard
NIC, but has a
transmitter/receiver for
sending signals via
radio waves.
Wireless networks are
popular as they allow the
user more freedom, such
as working outdoors.
Are there any problems with wireless networks?
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Wi-Fi hotspots
Wi-Fi technology allows users to wirelessly connect to the
Internet. Access points are set up at various locations from
which users can connect to a
wireless network
and access the Internet.
Many cafes and bars offer
wireless hotspots, allowing users
to work where they please.
What benefits and drawbacks
might establishments face
when offering Wi-Fi access?
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Benefits and drawbacks
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Mobile networks
It is now incredibly common to use mobile devices to access
a network. Most modern mobiles allow Internet access via 3G
(third generation) networks.
It’s not just mobiles though.
Tablet computers, PDAs,
E-readers and even gaming
devices like the Nintendo DS are
all being created with the ability
to connect to local area
networks (LANs) or wide area
networks (WANs) without the
need for cables.
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Packets
Each computer on a network has to have a network address
so that the data knows where it is being sent.
IP192.168.10.2
Computers break down data into
small parts so they can find the
quickest route to their destination.
These small parts are called packets
and will be reassembled when they
arrive at the right destination.
Computers connected to the Internet have their own IP
address to allow data packets to arrive at the right location.
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URLs
The domain name system links the IP address (e.g.
217.27.240.45) with the text name or web address (e.g.
http://www.boardworks.co.uk). This means that users only
have to remember a short name instead of lots of numbers.
Most people still refer to
this as a website address
but its proper name is a
URL or Uniform
Resource Locator.
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URLs
URLs are usually made up of these parts:
www, standing for World Wide Web
an organization name
(.boardworks)
a top level domain (.co)
a country (.uk).
There are many top level domains, for instance .com,
.org (organization), .sch (school) and .ac (university).
When you are deciding whether the information from a
website is reliable, take a look at the URL. It will give you
some idea about the source of the information.
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Speaking the same language
To allow different types of computers in different parts of the
world to interact, there has to be some agreement about
how they communicate.
These standards are called protocols.
http is the first part of many web
addresses – it stands for hypertext
transfer protocol, and states the
protocol that the site will use to
communicate.
HTML stands for Hypertext Markup
Language, and it is the standard
language for writing web pages.
What does HTTPS stand for?
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Acronyms
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True or false?
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