NetworksNetworks. 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 s, 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 school folder Share devices attached to the network (like a printer) 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 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 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 I like rock’n’roll Dude what’s your favourite band????????1 like, Nirvana dude haw naw m8 get a clue who is this glasgowbob? whit man watch oot like whatever man hello chaps, what’s going on? 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 description Any search engine that you enter your brief description into a single search box uses simple search. You can do this on: Google Yahoo Google images < 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