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Discovering Computers 2008 Chapter 9 Communications and Networks.

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Presentation on theme: "Discovering Computers 2008 Chapter 9 Communications and Networks."— Presentation transcript:

1 Discovering Computers 2008 Chapter 9 Communications and Networks

2 Communications -- Telecommunications What are computer communications? Next p. 460 Fig. 9-1 mainframe computers smart phones notebook computers servers Web-enabled PDAs desktop computers Tablet PCs GPS receivers  Process in which two or more computers or devices transfer data, instructions, and information Blackberry Video

3 Networks – Local Area Network What is a local area network (LAN)? Next p. 471 Fig  Network in limited geographical area such as home or office building  Metropolitan area network (MAN) connects LANs in city or town

4 Communication Devices -- Hardware Requirements  Sending Device  Initiates Instruction to Transmit  Communications Device  Connects Sending Device to Channel  Connects Channel to Receiving Device  Communications Channel or Transmission Media  Media on Which Data Travels  Receiving Device  Accepts Transmission p. 460

5 Communications Devices What are examples of communications devices? Next p. 482 Common types are dial-up modems, ISDN and DSL modems, cable modems, network cards, wireless access points, routers, and hubs ISDN and DSL modems send and receive data from ISDN and DSL lines

6 Communications Channel also known as Transmission Media Next p. 490 Fig Transfer Rates for Various Types of LANs Using Physical Transmission Media  Wire, cable, and other tangible materials used to send communications signals What are examples of transmission media?

7 Wireless Transmission Media What is wireless transmission media? p. 494 Fig  Used when inconvenient, impractical, or impossible to install cables  Includes Bluetooth and IrDA

8 Networks Collection of Computers & Devices  Connected via  Communications Devices -- Slide 5  Transmission Media – Slide 6

9 Uses of Computer Communications What are some uses of communications technology? Next p. 462 WebWebInternetInternet Instant Messaging Internet Telephony NewsgroupsNewsgroups Chat Rooms Web Folders Fax Machine or Computer Fax/Modem Video Conferencing FTPFTP

10 Uses of Computer Communications What are Wireless Messaging Services?  Text Messaging  Send / Receive Short Text Messages Using Phone  Picture Messaging  Send / Receive Graphics, Pictures, Video, Sound

11 Uses of Computer Communications What is a global positioning system (GPS)? Next p. 466 Fig. 9-6 Step 1. GPS satellites orbit Earth. Every 1/1000 of a second, each satellite sends a signal that indicates its current position to the GPS receiver. Step 2. A GPS receiver (such as in a car, a wearable device, a smart phone, a handheld device, or a collar) determines its location on Earth by analyzing at least 3 separate satellite signals from the 24 satellites in orbit. Click to view Web Link, click Chapter 9, Click Web Link from left navigation, then click GPS below Chapter 9

12 Uses of Computer Communications What is groupware? Next p. 467 Fig. 9-7  Groupware is software that allows people work together and share information MS Office 2007: SharePoint Server: A big share drive to share files with others at the college.: SharePoint Server SharePoint video Google Wave

13 Network Types LAN (Local Area Network)  Network in Limited Geographical Area  Typically Within a Building

14 Network Types What is a wide area network (WAN)? Next p. 472 Fig  Network that covers large geographic area using many types of media  Internet is world’s largest WAN

15 Network Types What is a client/server network? Next p. 472 Fig  One or more computers act as server and other computers, or clients, access server  Clients request RESOURCES on the server

16 Networks What is a site license? Legal agreement that allows multiple users to run a software package simultaneously License fee usually based on number of users or number of computers attached to network

17 Networks What are the components of a client/server network? Next p. 472 Fig  File server  Workstation  Network interface card  UPS  Network Operating System  Printers  Backups

18 Network Types What is a peer-to-peer network? Next p. 473 Fig  Simple network that connects fewer than 10 computers  Each computer, or peer, has equal capabilities

19 Network Types What is Internet peer-to-peer (P2P)? Next p Fig  Sometimes called a file sharing network  Enables users to connect to each other’s hard disks and exchange files directly Click to view Web Link, click Chapter 9, Click Web Link from left navigation, then click BitTorrent below Chapter 9

20 Criticism Illegal music/video sharing  Kazaa  Napster  The Pirate Bay Strain on ISP Bandwidth supply < Bandwidth demand

21 Network Topology Layout of devices in a network Popular types of topology Bus Ring Star

22 Bus Topology What is a bus network?  All computers and devices connect to central cable, or bus

23 Star Topology What is a star network? Next p. 475 Fig  All devices connect to a central device, called hub  All data transferred from one computer to another passes through hub

24 Networks What is a ring network? Next p. 474 Fig  Cable forms closed ring, or loop, with all computers and devices arranged along ring  Data travels from device to device around entire ring, in one direction

25 Networks What is an intranet? Next p. 475 Extranet allows customers or suppliers to access part of company’s intranet Typically includes connection to Internet Makes information accessible to employeesInternal network that uses Internet technologies Don’t confuse and intranet with:

26 Networks What is an extranet? Allows customers or suppliers outside of the company to access part of company’s intranet Customer checking package on Fed Ex’s intranet via the Internet

27 Bus Topology What is a bus network?  All computers and devices connect to central cable, or bus

28 Protocol & Standards -- Wired Ethernet  For LANs  Uses Bus or Star Topology  One of Most Widely Implemented Standards How Ethernet Cards Work

29 Protocol & Standards -- Wired TCP/IP-- Transmission Control Protocol/Internet Protocol  Commonly Used for Internet Transmissions  Packet Switching  Transmits Data by Breaking it Into Packets  Reassembles Data at Destination TCP/IP Animation

30 Network Communications Standards Wi-Fi identifies any network based on the standard that facilitates wireless communication Sometimes referred to as wireless Ethernet Compare speeds: n vs g

31 How to Setup a Wireless Network

32 Network Communications Standards Next p Fig Bluetooth limited to: 10 meters = 33 ft. TO 100 meters = 330 ft. Short-range Radio Technology IrDA Data Transferred via Infrared Light Waves

33 Protocols & Standards RFID -- Radio Frequency Identification – replace bar code reader  Uses Radio Signals  Communicates with Tag Placed in Object  Legislation  Nevada –Require Retailers to Inform Customers Product is Tagged  Rhode Island –No Government Agency can Use to Track Individuals  TX –Prohibit Schools from Using RFID on Students How RFID WorksRFID and Sushi

34 Network Communications Standards

35 Communications Over the Telephone Network What is a dial-up line?  Temporary connection using telephone line for communications  Costs no more than making regular call  Computers at any two locations can establish a connection using modems and telephone network

36 Communications Over the Telephone Network

37 bits per second (bps) The Telephone Network What is transfer rate? Speed at which a line carries data and information Faster the transfer rate, the faster you can send and receive data and information Usually expressed as a measure of bits per second kilobits per second (Kbps) megabits per second (Mbps) gigabits per second (Gbps)

38 Communications Over the Telephone Network What is a dedicated line? Next p. 482 Fig  ISDN  DSL  T-carrier line  ATM -- Asynchronous Transfer Mode  Always-on connection between two communications devices

39 Communications Devices --Wired What are ISDN and DSL modems? Next p. 485 Communications devices that send and receive digital ISDN and DSL signals Usually external devices in which one end connects to a telephone line and the other end connects to a port on the system unit

40 Communications Devices What is a cable modem? Next p Fig  Sends and receives data over cable television network  Much faster than dial-up modem or ISDN  Sometimes called a broadband modem Click to view Web Link, click Chapter 9, Click Web Link from left navigation, then click Cable Modems below Chapter 9

41 Cable Modem vs. DSL Cable Modem Advantage: Widespread Availability Disadvantage: Competition with shared users DSL Advantage: Not shared with other users Disadvantage: Radius of user and service limited Video –Cable & DSL

42 Communications Over the Telephone Network What is an ADSL ( asymmetric digital subscriber line)? Next  Popular type of DSL (Digital Subscriber Line)  Faster when receiving data than when sending data  Ideal for Internet access

43 Communications Devices A network card enables a computer or device to access a network Available in a variety of styles Wireless network cards often have an antenna same waves used by cell phones

44 Communications Devices A router connects multiple computers or other routers together and transmits data to its correct destination on a network Many are protected by a hardware firewall Fastest path available

45 Communications Devices A hub or switch connects several devices in a network together

46 What's the difference between a hub and a router? A hub just allows several network cables to be attached, putting several computers on the same network. A router has a processor that allows it to decide where to send traffic, and possibly to modify the details. A hub glues together an Ethernet network segment A router can do those functions plus route TCP/IP packets between multiple PCs on LAN and a WAN Some hubs include routers

47 Home Networks What is a home network? Next p Fig  Multiple computers connected in home  Several types of wired home networks  Ethernet — connect computers via cable  Powerline cable — use electrical lines in house  Phoneline — use telephone lines Click to view Web Link, click Chapter 9, Click Web Link from left navigation, then click Home Networks below Chapter 9

48 Communications Channel What is a communications channel? Next p. 491  Transmission media on which data travels in communications system – both wired and wireless Bandwidth is amount of data that can travel over a communications channel Transmission media are materials capable of carrying one or more signals

49 What is physical transmission media? p. 492 Fig. 9-36

50 Physical Transmission Media What are twisted-pair cable and coaxial cable? Next p. 493 Fig. 9-37—9-38  Twisted-pair cable is used for telephone systems and network cabling  Coaxial cable is often used for cable television wiring

51 Physical Transmission Media What is fiber-optic cable? Next p. 493 Fig  Capable of carrying significantly more data at faster speeds than wire cables  Less susceptible to interference (noise) and, therefore, more secure  Smaller size (thinner and lighter) 4/9/09 Fiber Optic Cable Security?

52 Wireless Transmission Media What is wireless transmission media? p. 494 Fig  Used when inconvenient, impractical, or impossible to install cables  Includes Bluetooth and IrDA

53 Wireless Transmission Media Microwave Station  Earth-based Reflective Dish  Contains Antenna, Transceivers  Uses Line-of-sight Transmission – straight line with no obstructions Universities, hospitals, government, cable television

54 Wireless Transmission Media Satellite  Space Station  Receives Microwave Signals  Broadcasts Signals Back to Earth-based Stations TV, GPS, air navigation


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