This chapter discusses computer communications and networks. It describes the components needed for successful communications including sending and receiving devices, communications software, and transmission media. Various network types such as LANs, WANs, intranets and extranets are defined. Common network devices like routers, hubs, switches and wireless access points are explained. Both physical wired media like twisted pair and fiber optic cables and wireless transmission media are covered. Network standards including Ethernet, TCP/IP, Wi-Fi, Bluetooth and others are also outlined.

1. Discovering
Computers 2009
Chapter 9
Communicatio
ns and
Networks

2. Chapter 9 Objectives
Discuss the components required for
successful communications
Explain the purpose of
communications software
Identify various sending
and receiving devices
Describe various types of lines for
communications over the telephone network
Describe uses of computer communications
Describe commonly used
communications devices
List advantages of using a network
Discuss different ways to set up
a home network
Differentiate among client/server,
peer-to-peer, and P2P networks
Identify various physical and wireless
transmission media
Describe the various network
communications standards

3. Communications

4. Communications
What are computer___________________?
communications
 Process in which two or more computers or devices transfer data,
instructions, and information

5. Communications
What is needed for successful communications?
Sending device
__________________— Communications Communications channel
__________________
initiates instruction to device — connects
transmit data, the sending device to media
instructions, or the communications on which data,
information channel instructions, or
information travel
Communications Receiving device
_________________
device — connects
accepts transmission of
the communications
data, instructions, or
channel to the
information
receiving device
p. 460 - 461

6. Uses of Computer Communications

7. Uses of Computer Communications
What are some uses of communications technology?
p. 462

8. Uses of Computer Communications
What are wireless messaging services?
Text messaging Wireless instant
allows users to send messaging allows
and receive short wireless mobile
text messages on a devices to exchange
phone or other Picture/video messages
mobile device messaging allows
users to send
graphics, pictures,
video clips, sound
files, and short text
messages
p. 463 - 464

9. Uses of Computer Communications
What are _______________________________
wireless Internet access points
 allows wireless
connection to Internet
in public location
 3G and 4G
networks
 _______________is a
Cybercafé
coffee house that
provides computers
with Internet access
p. 464-465 Fig. 9-4

10. Uses of Computer Communications
What is a _____________________________?
global positioning system (GPS)
A navigation system that consists of one or more earth-based
receivers that accept and analyze signals sent by satellites in
order to determine the receiver’s geographic location.
p. 466 Fig. 9-6

11. Uses of Computer Communications
 ____________________is working with other users connected
Collaboration
to a server
 Web conference
Groupware
 _______________is software that allows people work together
and share information
p. 467 Fig. 9-7

12. Uses of Computer Communications
 ___________________is voice message converted
Voice mail
to digital form
 _____________________describe standardized
Web services
software that enables programmers to create
applications that communicate with other remote
computers over the Internet or on an internal
business network
p. 468 Fig. 9-8

13. Networks
p. 469 Fig. 9-9

14. Networks
What is a network?
 Collection of
computers and
devices connected
via communications
devices and
transmission
media
p. 469 Fig. 9-9

15. Networks
Network classifications
 ____________is a network in limited geographical area
LAN
such as home or office building
 Wireless ____________
LAN (WLAN)
 _____________________________ connects _____s
Metropolitan area network (MAN) LA
in city or town N
 _____________________________ a network that
Wide area network (WAN) is
covers large geographic area using many types of media
 ____________is world’s largest_________
Internet WAN

16. Network
Network Architectures
 _____________: One or more computers act as host
Client/Server
computer and other computers access the host
computer
 _______________: Simple network that connects fewer
peer-to-peer
than 10 computers. Each computer has equal
capabilities
 _________________________: Enables users to
Internet peer-to-peer (P2P)
connect to each other’s hard disks and exchange files
directly. Sometimes called a file sharing network.
p. 472 Fig. 9-13

17. Network
Network Topology: the layout of the computers in a
network.
1. _____________: All computers and devices connect to
Bus network
central cable or bus
p. 472 Fig. 9-13

18. Network
Network Topology
1. _____________: Cable
Ring network
forms closed loop (ring),
with all computers and
devices arranged along ring.
Data travels from device to
device around entire ring, in
one direction
p. 472 Fig. 9-13

19. Network
Network Topology
1. _____________: All
Star network
devices connect to a central
device (hub or switch)
All data transferred from
one computer to another
passes through hub or
switch.
p. 472 Fig. 9-13

20. Networks
What is an___________?
intranet
Internal network that uses Internet technologies
Makes information accessible to employees
Typically includes connection to Internet
Extranet allows customers or suppliers to access
_________
part of company’s intranet
__________
p. 475

21. Network Communications
Standards
p. 476

22. Network Communications
Standards
___________ technology allows computers to contend
Ethernet
for access to network.
No controlling computers or devices.
 If two computers send data at same time,
a collision occurs and computers must send again
 Bus topology, but sometimes star topology
Token ring
_______________ technology controls access to network
by requiring devices to pass a special signal,
called token
p. 476

23. Network Communications
Standards
_____________________________________________
TCP/IP (Transmission Control Protocol/Internet Protocol)
technology transmits data by breaking it up into
small pieces, or packets.
• Commonly used for Internet transmissions
_______________ is a family of standards for
802.11 (Wi-Fi)
wireless LANs
p. 476

24. Network Communications
Standards
___________ Short-range radio waves transmit
Bluetooth
data between Bluetooth devices
• Contains a small chip to communicate with each other.
_______ is a specification allows data to be
WAB
transferred wirelessly via short-range radio waves.
_______ specification allows data to be transferred
IrDA
wirelessly via infrared light waves.
p. 476

25. Network Communications
Standards
___________ uses radio signals to communicate
RFID
with a tag placed in an object
• Radio Frequency Identification.
_______ is a standard that specifies how wireless
WiMAX
devices communicate over the air in a wide area.
• Worldwide Interoperability for Microwave Access
_______ allow wireless mobile devices
WAP
to access Internet.
• Wireless Application Protocol
• Use client/server network.
p. 476

26. Communications Software

27. Communications Software
What is communications software?
 Programs that help users establish connection to Internet,
other network, or another computer
 Programs that help users manage transmission of data,
instructions, and information
 Programs that provide an interface for users to
communicate with one another
p. 480

28. Communications Over the Telephone Network
p. 481 Fig. 9-23

29. Communications Over the Telephone Network
 _______________________________________________:
public switched telephone network (PSTN)
Worldwide telephone system that handles voice-oriented
telephone calls.
The entire telephone network uses digital technology.
But, the final link from the local telephone company to a
home often uses analog.
p. 481 Fig. 9-23

30. Communications Over the Telephone Network
Various lines that use the telephone network for data
communications
1. _______________ Temporary connection using
dial-up line
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
1. _______________ Always-on connection between
Dedicated line
two communications devices
 There are five types of lines.
p. 481

31. Communications Over the Telephone Network
Dedicated lines
 _______________ Integrated Services Digital
ISDN lines
Network.
Require both ends of the connection have ________
ISDN
modem.
 __________Digital Subscriber Line
DSL
For the small business or home user
 __________Fiber to the Premises
FTTP
Use fiber-optic cable to provide extremely high-
speed Internet access
p. 481

32. Communications Over the Telephone Network
Dedicated lines
 _______________ Long-distance digital telephone
T-Carrier lines
lines that carry multiple signals over a single
communications line.
T1 line is most popular.
 __________ Asynchronous Transfer Mode
ATM
Very high speed.
Large amounts of traffic use this.
p. 481

33. Communications Devices
p. 484

34. Communications Devices
_________________
Dial-up modem
 Converts digital signals to analog signals and vice versa
 Usually in the form of an adapter card
p. 485

35. Communications Devices
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

36. 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
p. 484 - 486 Fig. 9-28

37. Communications Devices
What is a________________?
wireless modem
 Allows access to the
Web wirelessly from
a notebook
computer, a smart
phone, or other
mobile device
 Typically use the
same waves used by
cellular telephones

38. Communications Devices
What is a______________?
network card
 Adapter card, PC
Card, ExpressCard
module, USB
network adapter, or
flash card that
enables computer or
device to access
network
 Sometimes called
network interface
card (NIC)
p. 486 - 487 Fig. 9-30

39. Communications Devices
What is a_____________________?
wireless access point
 Central
communications
device that allows
computers and
devices to transfer
data wirelessly among
themselves or
wirelessly to a wired
network
p. 487 Fig. 9-31

40. Communications Devices
What is a____________?
router
 Connects computers and
transmits data to correct
destination on network
 Routers forward data on
Internet using fastest available
path
 Some routers have a built-in
hardware firewall

41. Communications Devices
What is a_______________?
hub or switch
 Device that provides central
point for cables in network

42. Home Networks
What is a home network?
 Multiple computers
connected in home
 Several types of home
networks
 Ethernet — connect
computers via cable
 Powerline cable —
use electrical lines in house
 Phoneline — use
telephone lines

43. Communications Channel

44. Communications Channel
What is a communications channel?
 Transmission media on which data travels in
communications system
Transmission media
are materials or
substances capable of
carrying one or more Bandwidth is amount of
signals data that can travel
over a communications
channel

45. Physical Transmission Media
What is physical transmission media?
 Wire, cable, and other tangible materials used
to send communications signals
p. 492 Fig. 9-36

46. Physical Transmission Media
 Twisted-pair
______________cable consists of one or more twisted-pair wires
bundled together. It is used for telephone systems and network cabling
 Coaxial
_________cable consists of a single copper wire. It is often used for
cable television wiring
p. 493 Fig. 9-37—9-38

47. Physical Transmission Media
What is __________cable?
fiber-optic
 Consists of dozens or
hundreds of thin
strands of glass or
plastic
 Capable of carrying
significantly more
data at faster speeds
than wire cables
 Less susceptible
to interference
(noise) and, therefore,
more secure

48. 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

49. Wireless Transmission Media
 ________________
Broadcast radio
distributes radio
signals over long
and short distances
 ________________
Cellular radio
is form of
________________
broadcast radio
used for mobile
communications

50. Wireless Transmission Media
What is a __________station?
microwave
 Earth-based
reflective
dish used for
microwave
communications
 Must transmit in
straight line with
no obstructions

51. Wireless Transmission Media
What is a_______________________?
communications satellite
 Space station
that receives microwave
signals from earth-based
station, amplifies signals,
and broadcasts signals
back to any number of
earth-based stations

52. Summary of Communications and Networks
Communications terminology
and applications
Various communications
devices, media, and procedures
How to join computers into a network
Chapter 9 Complete