networksnetworks. what is a network? standard grade computing studies
TRANSCRIPT
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NetworksNetworksNetworksNetworks
. What is a network?
Standard Grade Computing StudiesStandard Grade Computing StudiesStandard Grade Computing StudiesStandard Grade Computing Studies
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Stand Alone or Networked?
• A stand alone computer is one that is not connected to a network
• This could be a desktop computer or a laptop that has no wired or wireless connection.
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What is a Network?• A series of computers linked together
so that they can send and receive data.• We use them for sending e-mails,
downloading files, shopping, etc
• You need to know about– Local Area
Network (LAN)– The Internet
<- What is a network?
Local Area Networks ->
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Local Area Network (LAN)• Cover a small area such as one room or
building.– Our school has a LAN
• Each computer on a LAN is called a station
• One station is called the file server. – The file server is
where all the data & files are kept
<- LANs LAN Advantages ->
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Advantages of a LAN
• Share data e.g. files in Our school folder
• Share devices attached to the network (like a printer)
• E-mail• Security ..Passwords ..Different
levels of access • You can log onto any station
connected to the LAN
<- LAN Advantages Ex 1 ->
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Exercise 1
<- LAN Advantages Transmission meda ->
1.What is a LAN?
2 Describe your school’s LAN
3. Write down 3 advantages of a LAN
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Transmission media for LAN
• Stations can be connected by cables or wireless technology
Cables:Coaxial cablesTwisted-pair Cabling
<- Ex1 Wireless ->
Optical fibre Uses light beams to transmit data at High speedsExpensive but doesn't get interference
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Fibre Optic Cable• High speeds:
– Uses light beams to transmit data at High speeds { 100 terabytes per second is possible}
• Doesn’t get interference { unlike copper wire cable}
• More secure: – Difficult to intercept data on a fibre
optic cable• Expensive to install
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Transmission media for LAN
•Wireless– Infrared communication
• Used for wireless mouse and keyboard
– Bluetooth• Range of about 10 metres
– WIFI (Wireless Fidelity Alliance)
• Range of about 12-50 metres
Bluetooth & WIFI use radio waves<- Transmission media NICs ->
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<- Client/Server WANs ->
Exercise 2
1. Name 2 types of cable used in a network.
2. What type of cable does the school have on its LAN?
3. How can you link up the computers at home without using cables?
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Client/ServerClient/Server• Clients are workstations• Servers are central
computers• Servers have:
– powerful processors– Large memory capacity
• Clients are workstations• Servers are central
computers• Servers have:
– powerful processors– Large memory capacity
<- NICs Ex2 ->
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Client/Server
• The servers provide the resources for the computers { clients} connected to the network for example:
• Printer servers• File Server• Proxy server
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Client/Server
• In a client server network it is possible to :– organise Security for the whole
network– organise Backups for all the data on
the network– control who can access the network by
setting up accounts {with IDs and passwords}
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Peer to Peer network• In a peer to peer network there is
no central server.• The computers are linked together
to enable them to send and receive data.
• Each computer must back up its own data and organise its own security
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Peer to Peer Network
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Peer to Peer network• Since there is no centrally
organised security of backup system on a Peer to Peer network:
• They are only suitable for ‘trusting’ environments’ e.g. home use.
• They are not suited to commercial or business use.
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The InternetThe Internet
• A network of networks• Can be accessed by any internet-
ready computer system.• You need:
– A telecommunications connection such as a modem or broadband
– A browser– A link to an Internet Service Provider
<- Ex5 Modems and Dialup ->
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Transmission Media for The Internet
• The Internet uses Telecommunications links– It communicates information around
the world using:•Microwave transmission•Satellite links•Optical Fibre•Telephone cables
<- WANs Ex3 ->
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Services on the InternetServices on the Internet
• World Wide Web• Newsgroups• Chat rooms• Search Engines• E-Commerce
< Ex 6 WWW >
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BrowsersBrowsers
• Software that fetches and displays web pages
• Most people use Internet Explorer
• Hyperlinks let you click onto a new page
• The browser will remember web pages for you using favourites
<- Broadband Browser example ->
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Hyperlink
Favourites
Forward and back buttons
History
<- Browsers Online/Offline ->
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The World Wide WebThe World Wide Web
• Web pages stored in servers round the world
• Web pages are multimedia documents
• Linked with hyperlinks
< Internet services Hyperlinks >
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Other services on the netOther services on the net
• Newsgroups let you discuss particular subjects
• Chat rooms let you talk live to other people
• Netiquette is very important when using these services
<superdave> I like rock’n’roll<megabrad> Dude what’s your favourite band????????1<superdave> like, Nirvana dude
<glasgowbob> haw naw m8 get a clue<megabrad> who is this glasgowbob?<glasgowbob> whit man watch oot<superdave> like whatever man<Teacher> hello chaps, what’s going on?<glasgowbob> aw naw teacher man, pure bolt
** glasgowbob has signed out
< Ex7 Newsgroup pic >
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NewsgroupsNewsgroups
< Other services Search Engines >
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Search EnginesSearch Engines
• Simple searches – just type in a brief description
Any search engine that you enter your brief description into a single search box uses simple search.
You can do this on:
•Yahoo
•Google images
< Newsgroups Search example >
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Cloud Computing• Instead of buying and setting up
a network, they have simple computing devices:
• Which they use to access the internet
• And use the software, backing storage and servers provided by the Cloud Computing company.
• Basically, they rent the use of powerful network resources
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Cloud Computing: advantages
• Cloud users:• can have access to powerful
networks without having to spend lots of money setting up their own network = lower cost
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Cloud Computing: advantages
• Cloud users:– can update and change their software
as their needs change = flexibility– have access to technical support =
lower maintenance / staff costs– are billed only for the services they use
and the length of time they use them == lower cost
– can easily scale up or down their network resources as their needs dictate =flexibility
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Cloud Computing: advantages
• Backup and recovery of data is guaranteed by the Cloud Provider
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Cloud Computing: disadvantages
• Security: having all an organisation’s data stored in ‘ the cloud’ can be a security risk e.g. from hackers, from malware– Many organisations keep ‘critical data’
backed up locally, just in case.
• It depends on a reliable speedy internet connection
• Can be locked into a contract
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Locally owned and managed network
• Gives local control over – Security– Backup regime
• But– Can cost a lot more to set up– Is not as flexible: not so easy to scale
up or down the hardware and software