1. Chapter 9 Communications and Networks

2. Communications -- Telecommunications
What are computer communications?
Process in which two or more computers or devices transfer data, instructions, and information
notebook computers
Web-enabled PDAs
smart phones
servers
GPS receivers
desktop computers
mainframe computers
Tablet PCs
p. 460 Fig. 9-1
Blackberry Video
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3. Networks – Local Area Network
What is a local area network (LAN)?
Network in limited geographical area such as home or office building
Metropolitan area network (MAN) connects LANs in city or town
p. 471 Fig. 9-10
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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
Communication Device = modem or wireless
Channel = media and is the material that carries the signal: wired such as cable or wireless such as bluetooth
p. 460

5. Communications Devices
What are examples of communications devices?
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
p. 482
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6. Communications Channel also known as Transmission Media
What are examples of transmission media?
Transfer Rates for Various Types of LANs Using Physical Transmission Media
Wire, cable, and other tangible materials used to send communications signals
e.g. DSL modem is the device; the copper wire in the modem is the channel or transmission medida
p. 490 Fig. 9-35
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7. Wireless Transmission Media
What is wireless transmission media?
Used when inconvenient, impractical, or impossible to install cables
Includes Bluetooth and IrDA
p. 494 Fig. 9-40

8. Networks Collection of Computers & Devices Connected via
Communications Devices -- Slide 5
Transmission Media – Slide 6
Communications device: modem
Transmission media: telephone wire; cables; fiber optics

9. Uses of Computer Communications
What are some uses of communications technology?
Internet
Web
Instant Messaging
Chat Rooms
Newsgroups
Internet Telephony
FTP
Web Folders
Video Conferencing
Fax Machine or Computer Fax/Modem
p. 462
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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)?
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
p. 466 Fig. 9-6
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12. Uses of Computer Communications
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.
What is groupware?
A wave is equal parts conversation and document. People can communicate and work together with richly formatted text, photos, videos, maps, and more
SharePoint video
Google Wave
p. 467 Fig. 9-7
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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)?
Network that covers large geographic area using many types of media
Internet is world’s largest WAN
p. 472 Fig. 9-12
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15. Network Types What is a client/server network?
One or more computers act as server and other computers, or clients, access server
Clients request RESOURCES on the server
p. 472 Fig. 9-13
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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?
File server
Workstation
Network interface card
UPS
Network Operating System
Printers
Backups
p. 472 Fig. 9-12
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18. Network Types What is a peer-to-peer network?
Simple network that connects fewer than 10 computers
Each computer, or peer, has equal capabilities
p. 473 Fig. 9-14
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19. Network Types What is Internet peer-to-peer (P2P)?
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
p Fig. 9-15
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20. Criticism Illegal music/video sharing Strain on ISP Kazaa Napster
The Pirate Bay
Strain on ISP
Bandwidth supply <
Bandwidth demand
Revenge theory by economists
Music industry has been taking advantage of consumers
Sell 12-track albums for $15 only; no cheap singles
Make one or two good songs; rest is second-rate
Rationale -- Piracy is taking back money that industry “stole”
Lesser-known artists distribute free music
Artists believe that free distribution of music will result in greater attention
More $$$ from concerts because of online popularity
Some artists who are victim to piracy believe that from the exposure, they will profit more in live concert
Why authors don’t have to worry
Hard to read books on monitor (bad for eyes; long books)
Books in-print more portable than e-books
Non-fiction writers should worry more than fiction writers
Fiction to be read in order, non-fiction to be read depending on section
Textbook authors should worry

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?
All devices connect to a central device, called hub
All data transferred from one computer to another passes through hub
p. 475 Fig. 9-17
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24. Networks What is a ring network?
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
p. 474 Fig. 9-16
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25. Makes information accessible to employees
Networks
What is an intranet?
Internal network that uses Internet technologies
Makes information accessible to employees
Typically includes connection to Internet
Don’t confuse and intranet with:
Extranet allows customers or suppliers to access part of company’s intranet
p. 475
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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
TCP/IP stands for Transmission Control Protocol/Internet Protocol

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
TCP/IP stands for Transmission Control Protocol/Internet Protocol

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:
802.11p WAVE Wireless Access Vehicle Environments – transportation industry: speed of vehicles, airbag deployed?
802.11n vs g

31. How to Setup a Wireless Network

32. Network Communications Standards
Bluetooth limited to:
10 meters = 33 ft. TO
100 meters = 330 ft.
Short-range Radio Technology
IrDA
Data Transferred via Infrared Light Waves
Bluetooth exists in many products, such as telephones, the Wii and PS3. between two or more devices that are near each other in low-bandwidth situations. Bluetooth is commonly used to transfer sound data with telephones (i.e. with a Bluetooth headset) or byte data with hand-held computers (transferring files).
p Fig. 9-20
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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
Profile customer selections for marketing purposes, track movement thru store, possibly contents of purse thru cell phones; customer uses cell phone to find out more about the product
How RFID Works
RFID 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. 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
bits per second (bps)
kilobits per second (Kbps)
megabits per second (Mbps)
gigabits per second (Gbps)

38. Communications Over the Telephone Network
What is a dedicated line?
Always-on connection between two communications devices
ISDN
DSL
T-carrier line
ATM -- Asynchronous Transfer Mode
Integrated Services Digital Network; FTTH – Fiber-to-the HOME; FTTB – Fiber to the Building; Both allow home and business high speed access to the Internet
p. 482 Fig. 9-24
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39. Communications Devices --Wired
What are ISDN and DSL modems?
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
p. 485
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40. Communications Devices
What is a cable modem?
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
p Fig. 9-28
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41. Cable Modem vs. DSL Cable Modem Advantage: Widespread Availability
Video –Cable & DSL
Cable Modem
Advantage:
Widespread Availability
Disadvantage:
Competition with shared users
DSL
Not shared with other users
Radius of user and service limited

42. Communications Over the Telephone Network
What is an ADSL (asymmetric digital subscriber line)?
Popular type of DSL (Digital Subscriber Line)
Faster when receiving data than when sending data
Ideal for Internet access
Test speed of modem:
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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?
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
p Fig. 9-34
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48. Communications Channel
What is a communications channel?
Transmission media on which data travels in communications system – both wired and wireless
Transmission media are materials capable of carrying one or more signals
Bandwidth is amount of data that can travel over a communications channel
p. 491
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49. What is physical transmission media?
p. 492 Fig. 9-36

50. Physical Transmission Media
What are twisted-pair cable and coaxial cable?
Twisted-pair cable is used for telephone systems and network cabling
Coaxial cable is often used for cable television wiring
p. 493 Fig. 9-37—9-38
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51. Physical Transmission Media
What is fiber-optic cable?
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)
How fiber optic tubes are manufactured
4/9/09 Fiber Optic Cable Security?
p. 493 Fig. 9-39
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52. Wireless Transmission Media
What is wireless transmission media?
Used when inconvenient, impractical, or impossible to install cables
Includes Bluetooth and IrDA
p. 494 Fig. 9-40

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