Isd&d networks

Networks

. What is a network?

Standard Grade Computing Studies

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.

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 ->

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 ->

Advantages of a LAN

• Share data e.g. files in Our schoolfolder

• 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 ->

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

Transmission media for LAN

• Stations can be connected by cables or

wireless technology

Cables:

Coaxial cables

Twisted-pair Cabling

<- Ex1 Wireless ->

Optical fibre

Uses light beams to transmit data at High

speeds

Expensive but doesn't get interference

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

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 ->

<- 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?

Client/Server

• Clients are workstations

• Servers are central computers

• Servers have:

– powerful processors

– Large memory capacity

<- NICs Ex2 ->

Client/Server

• The servers provide the resources for

the computers { clients} connected to

the network for example:

• Printer servers

• File Server

• Proxy server

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}

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

Peer to Peer Network

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.

The 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 ->

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 ->

Services on the Internet

• World Wide Web

• Newsgroups

• Chat rooms

• Search Engines

• E-Commerce

< Ex 6 WWW >

Browsers

• 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 ->

Hyperlink

Favourites

Forward

and back

buttons

History

<- Browsers Online/Offline ->

The World Wide Web

• Web pages stored in servers round the world

• Web pages are multimedia documents

• Linked with hyperlinks

< Internet services Hyperlinks >

Other 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 >

Newsgroups

< Other services Search Engines >

Search Engines

• Simple searches – just type in a brief descriptionYou can do this on:

• Google

• Yahoo

• Google images

• ASK

• Dogpile

• Bing

• DuckDuckGo

< Newsgroups Search example >

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

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

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

Cloud Computing: advantages

• Backup and recovery of data is

guaranteed by the Cloud Provider

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

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