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  • Networks

    1. 1. Networks Standard Grade Computing Studies . What is a network?
    2. 2. What is a Network? <ul><li>A series of computers linked together so can send and receive data. </li></ul><ul><li>We use them for sending e-mails, downloading files, shopping, etc </li></ul><ul><li>They are divided into two types: </li></ul><ul><ul><li>Local Area Network (LAN) </li></ul></ul><ul><ul><li>Wide Area Network (WAN) </li></ul></ul><- What is a network? Local Area Networks ->
    3. 3. Local Area Network (LAN) <ul><li>Cover a small area such as one room or building. </li></ul><ul><ul><li>Our school has a LAN </li></ul></ul><ul><li>Each computer on a LAN is called a station </li></ul><ul><li>One station is called the file server. </li></ul><ul><ul><li>The file server is where all the data & files are kept </li></ul></ul><- LANs LAN Advantages ->
    4. 4. Advantages of a LAN <ul><li>Share data e.g. files in Our school folder </li></ul><ul><li>Share devices attached to the network (like a printer) </li></ul><ul><li>E-mail </li></ul><ul><li>Security ..Passwords ..Different levels of access </li></ul><ul><li>You can log onto any station connected to the LAN </li></ul><- LAN Advantages Ex 1 ->
    5. 5. Exercise 1 <ul><li>What is a LAN </li></ul><ul><li>What is a WAN </li></ul><ul><li>Does the school have a LAN or a WAN? </li></ul><ul><li>Write down 3 advantages of a LAN </li></ul><- LAN Advantages Transmission meda ->
    6. 6. Transmission media for LAN <ul><li>Stations can be connected by cables or wireless technology </li></ul><ul><li>Cables : </li></ul><ul><ul><li>Coaxial cables </li></ul></ul><ul><ul><li>Twisted-pair Cabling </li></ul></ul><ul><li>Optical fibre </li></ul><ul><ul><ul><li>Uses light beams to transmit data </li></ul></ul></ul><ul><ul><ul><li>Expensive but doesn't get interference </li></ul></ul></ul><- Ex1 Wireless ->
    7. 7. Transmission media for LAN <ul><li>Wireless </li></ul><ul><ul><li>Infrared communication </li></ul></ul><ul><ul><ul><li>Used for wireless mouse and keyboard </li></ul></ul></ul><ul><ul><li>Bluetooth </li></ul></ul><ul><ul><ul><li>Range of about 10 metres </li></ul></ul></ul><ul><ul><li>WIFI ( Wireless Fidelity Alliance) </li></ul></ul><ul><ul><ul><li>Range of about 12-50 metres </li></ul></ul></ul><ul><li>Bluetooth & WIFI use radio waves </li></ul><- Transmission media NICs ->
    8. 8. Network Interface Cards <ul><li>Takes data sent by computer and stores it in its own memory </li></ul><ul><li>Adapts data to make sure it follows the communication rules of the network </li></ul><ul><li>Takes data coming in from network and passes it to the processor </li></ul><- Wireless Client/Server ->
    9. 9. Client/Server <ul><li>Clients are workstations </li></ul><ul><li>Servers are central computers </li></ul><ul><li>Servers have: </li></ul><ul><ul><li>faster processors, </li></ul></ul><ul><ul><li>More memory </li></ul></ul><ul><li>Used for: </li></ul><ul><li>Network printing </li></ul><ul><li>Holding data </li></ul><ul><li>or applications </li></ul><ul><li>Internet access </li></ul><- NICs Ex2 ->
    10. 10. 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 WANs ->
    11. 11. Wide Area Networks (WAN) <ul><li>Connect computers across large distances </li></ul><ul><li>Spread across countries & cities worldwide using telecommunications links </li></ul><ul><li>Similar advantages to LAN but on a bigger scale. </li></ul><- Ex2 WAN Trans. Media ->
    12. 12. Transmission Media for WANs <ul><li>Telecommunications links </li></ul><ul><ul><li>The communication of information over a distance using: </li></ul></ul><ul><ul><ul><li>Microwave transmission </li></ul></ul></ul><ul><ul><ul><li>Satellite links </li></ul></ul></ul><ul><ul><ul><li>Optical Fibre </li></ul></ul></ul><- WANs Ex3 ->
    13. 13. <ul><li>Exercise 3 </li></ul><ul><li>What kind of network would connect computers in Aberdeen, Glasgow London and New York? </li></ul><ul><li>How do computers send data from Glasgow to New York? </li></ul><ul><li>Why would big networks want to use fibre optic cables? </li></ul><- WANs trans media Multi-Access Comp ->
    14. 14. Multi-access Computers <ul><li>Powerful computers </li></ul><ul><li>Users access system at the same time </li></ul><ul><li>Processing power is shared </li></ul><ul><li>Memory is shared </li></ul><ul><li>Backing storage is shared </li></ul><- Ex3 Multi-Access Comp 2 ->
    15. 15. Multi Access Computers 2 <ul><li>Terminals have a keyboard and monitor </li></ul><ul><li>They interact with the main processor </li></ul><ul><li>They load data from the main backing storage </li></ul><ul><li>They display data held on the system </li></ul><ul><li>A terminal itself does not have much power </li></ul><- Multi access comp Multi-Access Comp 3 ->
    16. 16. Multi-access computers 3 <ul><li>Each terminal gets a slice of the processor’s time </li></ul><ul><li>It goes round users quickly so they are not aware that they are sharing </li></ul><ul><li>Large organisations use multi-access computers to store and process their data </li></ul><- Multi access comp 2 Net security ->
    17. 17. Network Security <ul><li>Security methods include: </li></ul><ul><ul><li>Passwords </li></ul></ul><ul><ul><li>Encryption </li></ul></ul><ul><ul><li>Physical methods </li></ul></ul><- Multi access 3 Physical security ->
    18. 18. <ul><li>Installing network computers </li></ul><ul><li>with a lock that has to be opened </li></ul><ul><li>before people can even log on. </li></ul><ul><li>Installing network computers that </li></ul><ul><li>have no floppy disk drives or CD drives. </li></ul><ul><li>Use security locks on the rooms </li></ul><ul><li>where the computers are stored. </li></ul>Physical security measures <- Net Security Physical security example ->
    19. 19. A physical lock being used to secure a computer . <- Physical Security Software security ->
    20. 20. Software Security Measures <ul><li>User I.Ds and passwords </li></ul><ul><li>Fingerprints </li></ul><ul><li>Smartcards </li></ul><ul><li>Encryption </li></ul><- Physical Security ex Encryption >
    21. 21. Encryption <ul><li>A message is converted to code before it is sent over the network </li></ul><ul><li>At the other end, the code is decrypted and read by the user who has the “key” to the code. </li></ul>< Soft security measures Ex 4>
    22. 22. Exercise 4 < Encrpytion Elec. Comms ->
    23. 23. Electronic Communication <- Ex 4 Instant Msging ->
    24. 24. Instant Messaging <ul><li>Messages sent from PC to PC </li></ul><ul><li>You log in then send messages </li></ul><ul><li>Sometimes you can use a webcam/microphone </li></ul><-Elec Comms Mobile text msgs ->
    25. 25. Mobile text messages <ul><li>Short messages of up to 160 characters </li></ul><ul><li>Stored on central computer systems </li></ul><ul><li>Sent to pages, mobile phones and palmtop computers </li></ul><- Instant Msgs E-mail ->
    26. 26. Electronic Mail (e-mail) <ul><li>E-mails are like letters sent by computer </li></ul><ul><li>They can be sent anywhere in the world </li></ul><ul><li>Email is very quick and very cheap compared to real letters </li></ul><- mobile texts E-mail advantages ->
    27. 27. Advantages of e-mail You need to copy of a message to send it to more than one person You can send the same message to many people easily You can collect email just at your address You can check your e-mail anywhere Costs more to send further away Costs the same to send to any part of the world Costs the price of a stamp or more Costs nothing apart from your ISP/phone bill Message sent in a day or more Message send in a few seconds Snail-mail (letters/post) E-mail <- E-mail Problems with E-mail ->
    28. 28. Problems with e-mail <ul><li>Viruses can be hidden in </li></ul><ul><li>e-mail attachments </li></ul><ul><li>‘ Spam’ or ‘junk mail’ can arrive </li></ul><- E-mail advantages E-mailing files ->
    29. 29. E-mailing files <ul><li>You can ‘attach’ files to e-mails </li></ul><ul><li>This sends the file as part of your email </li></ul><- Problems with E-mail Problems with attachments >
    30. 30. Problems with attachments <ul><li>File sizes can be limited </li></ul><ul><li>Viruses travel in attachments </li></ul>E-mailing filesurity Netiquette ->
    31. 31. Netiquette <ul><li>Netiquette is a set of rules for using e-mail </li></ul><ul><li>They are designed to stop people misusing the service or harming others </li></ul><- Probs with attachments Ex 5 ->
    32. 32. Exercise 5 <- Probs with attachments Internet ->
    33. 33. The Internet <ul><li>A network of networks </li></ul><ul><li>Can be accessed by any internet-ready computer system. </li></ul><ul><li>You need: </li></ul><ul><ul><li>A telecommunications connection such as a modem or broadband </li></ul></ul><ul><ul><li>A browser </li></ul></ul><ul><ul><li>A link to an Internet Service Provider </li></ul></ul><- Ex5 Modems and Dialup ->
    34. 34. Modems and Dialup <ul><li>A modem changes computer signals into a form that can be sent down the phone line </li></ul><ul><li>Dialup uses a modem and phone line to connect to your ISP </li></ul><ul><li>Data is transmitted at 56Kbps </li></ul><- Internet Broadband ->
    35. 35. Broadband <ul><li>Uses high speed telecommunications links </li></ul><ul><li>Uses Digital Subscriber Line or Cable Modem </li></ul><ul><li>DSL speeds: 512Kbps download, 128Kbps upload </li></ul><ul><li>Cable modem speeds: up to 10Mbps download but usually around 1Mbps </li></ul><- Modems Browsers ->
    36. 36. Browsers <ul><li>Software that fetches and displays web pages </li></ul><ul><li>Most people use Internet Explorer </li></ul><ul><li>Hyperlinks let you click onto a new page </li></ul><ul><li>The browser will remember web pages for you using favourites </li></ul><- Broadband Browser example ->
    37. 37. Hyperlink Favourites Forward and back buttons History <- Browsers Online/Offline ->
    38. 38. Online/Offline <ul><li>When you can send and receive information over the network, your computer is online </li></ul><ul><li>When you cannot, it is offline </li></ul><ul><li>Dialup users may go offline to save money, or receive phone calls </li></ul><ul><li>You can download e-mails and read them offline </li></ul><- Browser ex ISPs ->
    39. 39. Internet Service Providers <ul><li>ISPs give you access to the Internet </li></ul><ul><li>The connection helps find web pages, access email and chat rooms </li></ul><ul><li>Choosing an ISP: </li></ul><ul><li>Cost </li></ul><ul><li>Service reliability </li></ul><ul><li>Time limits </li></ul><ul><li>Efficiency of the service – is it fast? </li></ul>< Online/Offline Mobile Internet ->
    40. 40. Mobile Internet Technology <ul><li>You can access the internet on the move using mobile devices </li></ul><ul><li>To do so, the devices need: </li></ul><ul><ul><li>Mobile phone technology </li></ul></ul><ul><ul><li>Mini browser </li></ul></ul><ul><ul><li>Internal memory </li></ul></ul><ul><ul><li>Processor </li></ul></ul><ul><li>These could be smartphones </li></ul><ul><li>They could also be palmtops.. </li></ul>< ISPs Mobile Internet Tech 2 >
    41. 41. Mobile Internet Technology 2 <ul><li>Palmtops with phone technology built in </li></ul><ul><li>Features such as: </li></ul><ul><ul><li>Touchscreens </li></ul></ul><ul><ul><li>WIMP HCI </li></ul></ul><ul><ul><li>Mini browser </li></ul></ul><ul><ul><li>Calendar </li></ul></ul><ul><ul><li>Database </li></ul></ul><ul><ul><li>Calculator </li></ul></ul>< Mobile Internet Tech Ex 6 >
    42. 42. Exercise 6 < Mobile Internet Tech Services on Internet >
    43. 43. Services on the Internet <ul><li>World Wide Web </li></ul><ul><li>Newsgroups </li></ul><ul><li>Chat rooms </li></ul><ul><li>Search Engines </li></ul>< Ex 6 WWW >
    44. 44. The World Wide Web <ul><li>Web pages stored in servers round the world </li></ul><ul><li>Web pages are multimedia documents </li></ul><ul><li>Linked with hyperlinks </li></ul>< Internet services Hyperlinks >
    45. 45. Hyperlinks <ul><li>Links web pages together </li></ul><ul><li>Clicking on a graphic or text </li></ul><ul><li>Click here to go to a web page </li></ul><- WWW Creating webpages >
    46. 46. Creating a web page <ul><li>Created using special authoring package </li></ul><ul><li>You have used FrontPage, which does this </li></ul><ul><li>Pages are built up using a GUI to make the web pages </li></ul><ul><li>Web pages can be “hand coded” in HTML. </li></ul>< Hyperlinks Webpage code ex >
    47. 47. <html> <head> <title> Networks </title> </head> <body bgcolor=“Green”> <h1 align= &quot;center&quot; > Networks and the Internet </h1> <p align= &quot;left&quot; > When to computers communicate with each other, they are making a <b> network </b> . We use networks all the time - our school computers are on a network, for instance. </p> </body> </html> < Creating webpages Web page display >
    48. 48. < web page code Ex 7>
    49. 49. Exercise 7 < Web page view Other net services >
    50. 50. Other services on the net <ul><li>Newsgroups let you discuss particular subjects </li></ul><ul><li>Chat rooms let you talk live to other people </li></ul><ul><li>Netiquette is very important when using these services </li></ul><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 >
    51. 51. Newsgroups < Other services Search Engines >
    52. 52. Search Engines <ul><li>Simple searches – just type in a brief description </li></ul><ul><li>Any search engine that you enter your brief description into a single search box uses simple search. </li></ul><ul><li>You can do this on: </li></ul><ul><li>Google </li></ul><ul><li>Yahoo </li></ul><ul><li>Google images </li></ul>< Newsgroups Search example >
    53. 53. < Search engines Complex search >
    54. 54. Complex Search <ul><li>Some searches will find too many results </li></ul><ul><li>For example: “Glasgow” gives many pages about Glasgow. </li></ul><ul><li>To narrow down the search, you can use a complex search </li></ul><ul><li>This is more specific so finds fewer but more accurate results. </li></ul>< Search ex Complex search ex >
    55. 55. <ul><li>This search will find all the web pages with the word “Glasgow” in them </li></ul><ul><li>It will NOT include websites that have either Rangers or Celtic in the page </li></ul><ul><li>It will ONLY include web pages that have Partick Thistle in the page </li></ul>< Complex search Ex 8 >
    56. 56. Exercise 8 < Complex ex Software >
    57. 57. Software <ul><li>Lots of software </li></ul><ul><li>Different agreements </li></ul><ul><li>You must stick to the rules of the agreement </li></ul><ul><li>Otherwise you break the law </li></ul>< Ex 8 Freeware >
    58. 58. Freeware <ul><li>Free to copy and give away </li></ul><ul><li>Cannot be changed or sold </li></ul><ul><li>Freeware can be drivers, games, and many other programs </li></ul>< Software Shareware >
    59. 59. Shareware <ul><li>Free 30 day trial period </li></ul><ul><li>After this, register or delete program </li></ul><ul><li>You can copy the unregistered program </li></ul>< Freeware Commercial >
    60. 60. Commercial software <ul><li>Bought in shops or online </li></ul><ul><li>Full price up front </li></ul><ul><li>Usually limited to making 1 backup </li></ul><Shareware Ex 9 >
    61. 61. Exercise 9 < Commercial software Video conferencing >
    62. 62. Video Conferencing <ul><li>Send audio and video to distant places </li></ul><ul><li>Point-to-point like a phone call </li></ul><ul><li>Multi-point with several people </li></ul>< Ex9 Video Conferencing Adv >
    63. 63. Video Conferencing - Advantages <ul><li>People all over the world can talk “face to face” </li></ul><ul><li>Can mean less travelling and saving money and the environment </li></ul><ul><li>Teams of workers can be brought together quickly </li></ul>< Video conferencing Networks and social issues >
    64. 64. Networks and social issues <ul><li>You can find out almost anything on the internet </li></ul><ul><li>There are billions of web pages </li></ul><ul><li>Anyone can put up a new web page </li></ul><ul><li>Is this good or bad? </li></ul>< Video conferencing - adv Including everyone >
    65. 65. Including everyone <ul><li>The internet is an advantage to those that have it </li></ul><ul><li>But some people have no access – and this is a disadvantage </li></ul><ul><li>More people can access the internet every day, but not everyone. </li></ul><ul><li>Public access helps but some countries cannot afford this </li></ul>< Networks & Social Issues Isolation >
    66. 66. Isolation <ul><li>People may stop meeting face to face </li></ul><ul><li>People might spend more time online than offline </li></ul><ul><li>This can be dangerous </li></ul><ul><li>People can become detached from the world </li></ul>< Including everyone Ex 10>
    67. 67. Exercise 10 < Isolation Legal Issues >
    68. 68. Legal Issues <ul><li>Hacking </li></ul><ul><li>Viruses </li></ul><ul><li>Financial Fraud </li></ul><ul><li>Copyright law </li></ul>< Ex 10 Privacy >
    69. 69. Privacy <ul><li>People disregard your rights when sending abusive emails, junk mail or chain-mail </li></ul><ul><li>There are three computer laws to deal with these people. </li></ul>< Legal Issues Computer Laws >
    70. 70. <ul><li>Makes it illegal to: </li></ul><ul><li>Make unauthorised copies </li></ul><ul><li>Run unauthorised copies </li></ul><ul><li>Transmit software over networks without permission </li></ul>Copyright, Designs and Patents Act 1988 <ul><li>Makes sure that data held on you is: </li></ul><ul><li>Kept safe and secure </li></ul><ul><li>Kept accurate </li></ul><ul><li>Backed up </li></ul><ul><li>Gives you the right to view and change most of the data held on you </li></ul>Data Protection Act 1998 <ul><li>Makes it illegal to: </li></ul><ul><li>Gain unauthorised access to computer system (hacking) </li></ul><ul><li>Make unauthorised modifications to computer materials </li></ul>Computer Misuse Act 1990 < Privacy Ethical issues >
    71. 71. Ethical Issues <ul><li>Networks are powerful tools </li></ul><ul><li>There are right and wrong ways of using them </li></ul><ul><li>They can be a powerful way to communicate </li></ul><ul><li>They can also be used to stir up hatred, crime and corruption </li></ul>< Computer laws Codes of Conduct >
    72. 72. Codes of Conduct <ul><li>Just like real life, people misuse networks and indulge in anti-social behaviour </li></ul><ul><li>Acceptable Use Policies help us to avoid problems </li></ul><ul><li>These are rules based on respect and the law </li></ul>If it is not OK in real life, will it ever be OK on the Internet? < Ethical issues Ex 12 >
    73. 73. Exercise 12 < Codes of Conduct