Strand 3.3 of IT Systems

1. Networks Strand 3.3 of IT Systems

2. What is a network? A Network is a collection of computers and devices connected together, often wirelessly via communication devices and transmission media, allowing computers to share resources.

3. Advantages of Networking • Facilitating communications • Sharing hardware • Sharing data and information • Sharing software • Transferring funds

4. LAN’s, MAN’s, WAN’s & BAN’s • Networks usually fall under the 3 categories: • Local Area Network (LAN) • Metropolitan Area Network (MAN) • Wide Area Network (WAN) • Future developments in Networks • Body Area Networks (BAN); where a series of wearable or implented body sensors can turn the human body into a router for wireless communication devices, allowing data to be transmitted from the body to technology in order to achieve a task. • For example, saving a word processing document to a portable wrist device and than walking to a touch activated printer.

5. Local Area Network (LAN) • a LAN is a network that connects computers and devices in a limited geographical area such as a home, school computer lab, office building or closely positioned group of buildings around university or college. • Node – each computer or device on a network, such as a desktop, printer/fax, large hard disks. Nodes are connected by via cables.

6. Wireless LAN (WLAN) • Is a LAN that has no physical connection between nodes. • Each node such as a computer or other devices must have wireless capability, wireless network card, USB network adapter, Express Card module, PC Card or flash card. E.g. Wireless access point like a wireless modem for Internet access,

7. Metropolitan Area Network (MAN) • high speed network that connects local area networks in a city or town and handles the communications activity across that region. Made up of one or more LAN’s, but covers a smaller geographic area compared to a MAN. • MAN network providers are telephone companies, cable TV operators and other organisations associated with MAN.

8. Wide Area Network (WAN) • Covers a large geographic area like a city, country, state, emirate or globally using communication channels that combine many types of media such as telephone lines, cables and radio waves. • The Internet is the largest WAN.

9. Network Architecture • Is the layout of computers, devices and various media in a network. • Can be categorised as: • Client/server • Peer-to-Peer

10. Client/Server Network • use to network 10 or more computers • Where one or more computers act as a server(master computer) or host computers • A Client is other computers or mobile devices on the network that rely on the server for their resources or instructions in order to use other devices like a printer. For example, a server might store a database of customers. The clients on the network access the customer database on the server.

11. Client/Server Network Advantages: Centralized management, Strong Security, Expansion and Create redundant systems Disadvantages: Expensive, difficult to implement and Central Point of failure

12. Peer-to-Peer Network • use to network 10 or less computers • Each computer or Peer can work as a server and as a client

13. Peer-to-Peer Network Advantages: Lower Cost, Easy to setup and good for temporary network setup Disadvantages: Limited growth, No central location, Weak Security, To many passwords

14. Internet Peer-to-Peer Network • A network that allows users to access each other’s hard disk and exchange files directly over the Internet. • Sometimes referred to as a file sharing network • Examples are: • Bit Torrent • Gnutella • Kazaa • Lime Wire – used to swap music files via Web

15. Business Benefits to P2P • Companies & employees exchange files • In e-commerce, it allows buyers & sellers to share information like database records

16. Network Topologies • Topology – is the physical layout of computers and devices in a communications network • 3 network topologies are: • Bus Network • Ring Network • Star Network

17. Bus Network • This network is made up of: • A bus • Cables • Personal computers • Other devices like a printer, modem, switch/hub

18. Bus Network • Advantages of a bus network are that computers can connect and disconnect without affecting the other machines. • Disadvantages of a bus network are bandwidth, if two machines are hogging the bus as they exchange some huge files, then the others have to wait. • problem becomes worse as the network grows. So a bus is good for small to medium sized networks.

19. Ring Network • This network is made up of: • Cable connections • Server • Client computers • Other devices like a printer, modem, switch/hub

20. Ring Network • Advantages of a bus network are: that it is simple to set up with no complicated addressing needed. So its useful for small office networks • Disadvantages of a bus network are: is that if one of the links is broken then computers on one side of the break can't communicate with those on the other side.

21. Star Network • This network is made up of: • Switch/hub • Server • Client computers • Cable connections • Other devices like a printer, modem, switch/hub

22. Star Network • Advantages of a bus network are: that each link to the server is independent of the others so the computers do not have to share bandwidth with each other (unlike a bus arrangement). • Disadvantages of a bus network are: that more cabling is needed that other network arrangements. • if the central server is broken, then the whole network is broken.

23. Intranets • What is the difference between the Internet and an Intranet? • An Intranet is a private network within a company and it is only available to staff or members of the organisation. • The Internet is a computer network that connects computers worldwide or public network • An Intranet example are applications containing information related to a company, for example, policies, procedures, rules, contact lists, social events, newsletters etc.

24. What is an extranet? • An Extranet is a computer network that allows businesses outside the central company to access their network. • For example, the car company Ford has its own (huge) internal computer network that spans the world. However, it allows some of its main suppliers direct access to a small part of the network in order to allow them to share data with Engineers and Purchasing staff.

25. Network Communication Standards • Network standards are guidelines that specify the way computers access the medium to which they are attached, the types of medium used, the speeds used on different types of networks, and types of physical cable and/or the wireless technology used.

26. Protocols • A protocol is a set of rules for the exchange of data between a terminal and a computer or between 2 computers. • For example transmission speed. If one machine is talking at 56,600bps and the other is listening at 28,800 bps, the message doesn’t get through. • Protocols include prearranged messages such as “are you ready?” ; “I am about to start sending a data file”

27. Protocols • Protocols for both wired and wireless networks include: • Ethernet • Token ring • TCP/IP • Wi-Fi • Bluetooth • UWB • IrDA • RFID • WiMAX • WAP

28. Ethernet • A network standard that specifies no central PC or device on the network (nodes) when data is transmitted • Is based on bus topology, but can be wired on a star pattern • Controls how devices (e.g. Modems, routers, ec) share access to media (e.g. Cables & lines) and how devices transmit data over communications channel.

29. Ethernet • Examples of Ethernet are cables that plug into PC’s and other devices like printers for networks

30. Token Ring • A token is a series of bits that function like a ticket • Only a device at a time with a token can transmit data over the network • Token ring is based on ring topology • Physical configuration of a network includes cables, network cards and devices • Data transfer rate can either 4 Mbps, 16Mpbs, 100 Mbps or 1 Gbps

31. TCP/IP • Transmission Control Protocol/Internet Protocol (TCP/IP) • TCP is responsible for checking that data has been delivered correctly from your computer (the client) to another computer (the server). If data is lost, then TCP requests that the data is re-sent. • packets are small pieces of a message divided up for transmission • PC’s use TCP/IP for uploading web pages over the Internet. Web page is broken up into packets with its own address and reassembled once the web page arrives at your computer. • Routers send packets over the Internet from web server to your PC

32. How TCP/IP sends data as Packets

33. Wi-Fi • Wireless fidelity or 802.11 • Uses radio technology within a LAN • 802.11 standards are 2 wireless devices communicate over the air • Wi-Fi works in conjunction with TCP/IP when accessing the Internet • Wi-Fi network is popular with hot spots, where users can connect to the Internet in shopping malls • Many homes & shops use Wi-Fi to network computers & devices wirelessly • In open areas Wi-Fi range is up to a range of 30 meters or more • University’s/colleges use Wi-Fi mesh network

34. How Wi-Fi technology works

35. Bluetooth • Bluetooth or 802.15 • Wireless technology that enables Mobile phones, Handheld computers & PC’s to communicate with each other regardless of OS • Uses radio technology like Wi-Fi to transmit data only up to a range of 10 meters • Used for room-size personal area networks (PAN) A Bluetooth devices contains a small chip that allows it communicate with other Bluetooth devices. If device is not Bluetooth enabled, than a Bluetooth wireless port adapter will convert existing USB port into a Bluetooth port

36. Ultra-Wideband • A low power, short-range radio wave technology • Transmits ultra-high-speed signals over a wide spectrum of frequencies • At 10 meters, data is transferred at 110 Mbps • up to 2 meters, data is transferred at 480 Mpbs • Best suited for transmission of large files like video, graphics & audio • For example files are transferred wirelessly from a digital video camera to a media player or displaying a slide show on a projector.

37. IrDA • Is infrared technology • Has a 1 meter range • Approximate speed of 9600 bps • Used for data exchange between personal digital assistants (PDA’s) • Requires a clear line of sight between sending and receiving data.

38. Radio Frequency Identification • Radio frequency identification • A reading tool that uses radio waves to communicate with RFID tags • RFID tag or transponder broadcasts its unique ID number to the reader, which digitizes the info for input into a computer • RFID tags or transponders can be cards, car sticker on a windscreen, grain of rice, bar codes on books, etc.. • The tag consists of an antenna and memory chip that transmits information via radiowaves

39. How RFID Toll Works • Student task: Read page 481, fig 9-21 and create a flow chart on how road tolls work using RFID standards. E.g. Refer to road tolls in Dubai. Email your work through to Mr. Greg

40. RFID versus Bar Codes • Bar code reader – a tool that uses light to read universal product codes, inventory codes and other codes created out of patterns of variable-width bars. E.g. Used at check outs in supermarkets • Bar code readers are attached to point-of-sale (POS) terminals • POS send scanned information to a computer, it determines price, calculates taxes and totals and records transaction • Reading text from books, magazines & other printed documents is challenging • RFID readers use radio waves to communicate with RFID tags • RFID tags can be read from a greater distance • Hard plastic antitheft cards attached to clothes at shops contain RFID tags for security purposes • RFID tags used to identify books, goods on pallets, etc • RFID tags are designed to be read by computers quickly and accurately

41. WiMAX • Worldwide interoperability for microwave access or 802.16 • Is a network standard used for wireless devices • A wireless alternative to cable or DSL services • A powerful tool for connecting Wi-Fi networks • Provides wireless broadband Internet access at a good price over long distances to business and home users • Many mobile devices have built in WiMAX standards

42. WiMAX Towers WiMAX towers have a 48 km radius, connects to the Internet or to another WiMAX tower

43. WAP • Wireless application protocol • Determines how mobile devices like smart phones can display content of Internet services such as Web, email and chat rooms. • Uses a client/server network • Mobile devices contain client software that connects to the server of the ISP

44. Communications Software • Consists of programs that: • Help users establish a connection to a another computer or network • Manage the transmission data, instructions and information • Provide an interface for users to communicate with one another • Examples of application software for communications are e-mail, FTP, web browser, chat rooms, instant messaging, video conferencing and VoIP

45. Communications over the Network • Public switched telephone network (PSTN) is a worldwide telephone system that handles voice-oriented telephone calls • Data, instructions and information are transmitted over telephone network using dial up lines or dedicated lines.

46. Dial up Lines • Is a temporary connection that uses one or more analog telephone lines for communicates • Costs more to operate than a phone call

47. Dedicated Lines • Is a type of always on connection that is established between two communications devices • Five types of dedicated lines are: • ISDN lines • DSL • FTTP • T-carrier lines • ATM

48. ISDN Lines • ISDN stands for integrated services digital network • Used for small business and home users • Is a standard for digital transmission of data over standard copper telephone lines • Can carry 3 or more signals through a telephone line, by multiplexing the signal

49. DSL • Digital subscriber line • Transmits at fast speeds on copper telephone wires • ADSL is the most popular DSL type • ADSL-asynchronous digital subscriber line • ADSL supports faster transfer speeds when receiving or downstreaming data and sending or upstreaming data • ADSL is ideal for Internet access • Do ADSL connections transmit data downstream faster than upstreaming?

50. FTTP • Fiber to the premises • Uses fiber optic cables to provide extremely high-speed Internet access • 2 types of FTTP are FTTH & FTTB • FTTH for home users • FTTB for organisations • With FTTP service, an optic terminal receives signals and transfers them to a router connected to your computer. • Will become more affordable when the cost of fiber optics decreases