This chapter discusses computer communications and networks. It describes the components needed for successful communications, including sending/receiving devices, communications devices, communications channels, and transmission media. The chapter discusses uses of computer communications like the internet, email, and collaboration software. It describes different types of networks including LANs, WANs, client/server networks, and peer-to-peer networks. Standards like TCP/IP, Ethernet, and wireless technologies are also covered. The chapter concludes with sections on communications software, devices, and setting up home networks.

1. Chapter 9
Communications
and Networks

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

3. Communications
What are computer communications?
Nextp. 460 Fig. 9-1
set-top boxes
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

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

5. Uses of Computer Communications
What are some uses of communications technology?
Nextp. 463
WebWebWebWebInternetInternetInternetInternet E-MailE-MailE-MailE-Mail
InstantInstant
MessagingMessaging
InstantInstant
MessagingMessaging FTPFTPFTPFTPNewsgroupsNewsgroupsNewsgroupsNewsgroupsChat RoomsChat RoomsChat RoomsChat Rooms
WebWeb
FoldersFolders
WebWeb
FoldersFolders
Fax MachineFax Machine
or Computeror Computer
Fax/ModemFax/Modem
Fax MachineFax Machine
or Computeror Computer
Fax/ModemFax/Modem
VideoVideo
ConferencingConferencing
VideoVideo
ConferencingConferencing

6. Uses of Computer Communications
What are Internet telephony and Internet printing?
p. 464 Next
Internet printingInternet printing
allows you to print
to network printer
from anywhere in
the world
Internet telephonyInternet telephony
enables you to talk
to other people over
the Internet
Sometimes called
Voice over IPVoice over IP

7. Uses of Computer Communications
What are Web services?
Nextp. 464 Fig. 9-4
 Software that enables
programmers to create
applications that
communicate with other
remote computers

8. Uses of Computer Communications
What are collaboration and
groupware?
Nextp. 465 Fig. 9-5
 Microsoft’s NetMeeting allows
collaboration
 Groupware is software
that allows people
to share
information
 Collaboration is working
with other users connected
to a server

9. Uses of Computer Communications
What are public Internet
access points and
cybercafés?
Nextp. 466 Fig. 9-6
Click to view Web Link,
click Chapter 9, Click Web Link
from left navigation,
then click Public
Internet Access Points
below Chapter 9
 Public Internet access
point allows wireless
connection to Internet
in public location
 Cybercafé is coffee
house that provides
computers with
Internet access

10. Uses of Computer Communications
What is a global positioning system (GPS)?
Nextp. 464 Fig. 9-7
Click to view Web Link,
click Chapter 9, Click Web Link
from left navigation,
then click GPS
below Chapter 9
Step 1.
GPS satellites orbit
Earth. Every
thousandth of a
second, each satellite
sends a signal that
indicates its current
position to the GPS
server.
Step 2.
A GPS receiver
(such as in a car,
a PDA, a watch,
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 video

11. Uses of Computer Communications
What are voice mail and wireless messaging services?
Nextp. 468 Fig. 9-8
 Voice mail is voice message converted to digital form
 Wireless messaging services include:
 Text Messaging
 Instant Messaging
 Picture Messaging

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

13. Networks
What is a local area
network (LAN)?
Nextp. 471 Fig. 9-10
Click to view Web Link,
click Chapter 9, Click Web Link
from left navigation,
then click LAN
below Chapter 9
 Network in limited
geographical area such
as home or office
building
 Metropolitan area
network (MAN) connects
LANs in city or town

14. Networks
What is a wide area
network (WAN)?
Nextp. 472 Fig. 9-11
 Network that covers
large geographic
area using many
types of media
 Internet is world’s
largest WAN

15. Networks
What is a client/server
network?
Nextp. 472 Fig. 9-12
 One or more computers
act as server and other
computers, or clients,
access server

16. Networks
What is a peer-to-peer
network?
Nextp. 473 Fig. 9-13
 Simple network
that connects
fewer than 10
computers
 Each computer,
or peer, has equal
capabilities

17. Networks
What is Internet peer-to-peer
(P2P)?
Nextp. 473 Fig. 9-14
Click to view Web Link,
click Chapter 9, Click Web Link
from left navigation,
then click P2P
below Chapter 9
 Enables users to
connect to each other’s
hard disks and
exchange files directly

18. Networks
What is a bus network?
Nextp. 474 Fig. 9-15
 All computers and
devices connect to
central cable,
or bus
 Example of network
topology (layout of
devices in network)
 Popular topologies are
bus, ring, and star

19. Networks
What is a ring network?
Nextp. 474 Fig. 9-16
 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

20. Networks
What is a star network?
Nextp. 475 Fig. 9-17
 All devices connect to
a central device, called
hub
 All data transferred
from one computer to
another passes
through hub

21. Networks
What are Ethernet and token ring?
Nextp. 475
Click to view Web Link,
click Chapter 9, Click Web
Link from left navigation,
then click Ethernet
below Chapter 9
Ethernet technology allows computers to contend
for access to network
 If two computers send data at same time,
a collision occurs and computers must send again
Token ring technology controls access to network
by requiring devices to pass a special signal,
called token

22. Networks
What are TCP/IP and 802.11?
Nextp. 476 Fig. 9-18
 TCP/IP (Transmission Control Protocol/Internet
Protocol) technology transmits data by breaking it up
into small pieces, or packets
 Commonly used for Internet transmissions
 802.11 is family of standards for wireless LANs

23. Networks
What is Bluetooth?
Nextp. 476 Fig. 9-19
 Short-range radio waves
transmit
data
between
Bluetooth
devices

24. Networks
What are IrDA, RFID, and Wireless Applications
Protocol (WAP)?
Nextp. 476
Click to view Web Link,
click Chapter 9, Click Web Link
from left navigation,
then click WAP
below Chapter 9
IrDAIrDA
specification allows
data to be transferred
wirelessly via infrared
light waves
IrDAIrDA
specification allows
data to be transferred
wirelessly via infrared
light waves
Wireless ApplicationsWireless Applications
Protocol (WAP)Protocol (WAP)
allow wireless mobile devices
to access Internet
Wireless ApplicationsWireless Applications
Protocol (WAP)Protocol (WAP)
allow wireless mobile devices
to access Internet
Click to view video
Radio FrequencyRadio Frequency
Identification (RFID)Identification (RFID)
uses radio signals to communicate
with a tag placed in an object
Radio FrequencyRadio Frequency
Identification (RFID)Identification (RFID)
uses radio signals to communicate
with a tag placed in an object

25. Networks
What is an intranet?
Nextp. 478
Extranet allows customers or suppliers to access
part of company’s intranet
Typically includes connection to Internet
Makes information accessible to employees
Internal network that uses Internet technologies

26. Communications Software
What is communications software?
Nextp. 478
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

27. Communications Software
What is an example of communications software?
Nextp. 479 Fig. 9-20
Step 1. After you start
the New Connection
Wizard and select
Connect to the Internet
and Set up my connection
manually in the dialog
boxes, click Connect
using a dial-up modem.
Step 2. Enter the name of your Internet service provider.
Step 3. Enter your Internet service provider’s
telephone number.
Step 4. Enter your account information.
Step 5. Click the Finish button to create the Internet connection.
 Configures home or office network and connects devices to existing network

28. Communications Over the Telephone Network
What is the public switched
telephone network (PSTN)?
Nextp. 480 Fig. 9-22
 Worldwide telephone
system that handles
voice-oriented
telephone calls

29. Communications Over the Telephone Network
What is a dial-up line?
Nextp. 480 Fig. 9-23
 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

30. Communications Over the Telephone Network
What is a dedicated line?
Nextp. 481 Fig. 9-24
 Four types are ISDN
line, DSL, T-carrier
line, and ATM
 Always-on connection
between two
communications
devices

31. Communications Over the Telephone Network
What is an ADSL (asymmetric digital subscriber line)?
Nextp. 482 Fig. 9-25
Click to view Web Link,
click Chapter 9, Click Web Link
from left navigation,
then click DSL
below Chapter 9
 Popular type of
DSL (Digital
Subscriber Line)
 Faster when
receiving data
than when
sending data
 Ideal for Internet
access

32. Communications Devices
What are examples of communications devices?
Nextp. 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

33. Communications Devices
What is a dial-up modem?
Next
Click to view Web Link,
click Chapter 9, Click Web Link
from left navigation,
then click Dial-Up Modems
below Chapter 9
p. 483 Figs. 9-26–9-27
 Converts digital signals to analog signals and vice versa
 Notebook computers often use PC Card modem

34. Communications Devices
What are ISDN and DSL modems?
Nextp. 484
Communications devices that send and
receive digital ISDN and DSL signals
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
Usually external devices in which one
end connects to a telephone line and the other
end connects to a port on the system unit

35. Communications Devices
What is a cable modem?
Nextp. 484 Fig. 9-28
 Sends and
receives data
over cable
television
network
 Much faster than
dial-up modem
or ISDN
 Sometimes called
a broadband
modem

36. Communications Devices
What is a network card?
Nextp. 485 Fig. 9-29
 Adapter card, PC Card, or
compact flash card that
enables computer or device to
access network
 Sometimes called
network interface
card (NIC)

37. Communications Devices
What is a wireless access point?
Nextp. 485 Fig. 9-30
 Central
communications
device that allows
computers and
devices to transfer
data wirelessly among
themselves or to wired
network

38. Communications Devices
What is a router?
Nextp. 486 Fig. 9-31
Click to view Web Link,
click Chapter 9, Click Web Link
from left navigation,
then click Routers
below Chapter 9
 Connects computers
and transmits data
to correct destination
on network
 Routers forward
data on Internet
using fastest
available path

39. Communications Devices
What is a hub?
Nextp. 486 Fig. 9-32
 Device that provides central
point for cables in network
Click to view animation

40. Home Networks
What is a home network?
Nextp. 487 Fig. 9-33
Click to view Web Link,
click Chapter 9, Click Web Link
from left navigation,
then click Home Networks
below Chapter 9
 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
 HomeRF (radio frequency) — wireless

41. Communications Channel
What is a communications channel?
Nextp. 489
 Transmission media on which data travels in
communications system
Bandwidth is amount of
data that can travel
over channel
Transmission media
are materials capable of
carrying one or more
signals

42. Communications Channel
How is a request sent over the Internet using a
communications channel?
Nextp. 489 Fig. 9-34
Step 1. The sending device
requests information using either
a physical transmission media
or a wireless transmission media.
Step 2. When the request leaves
the ISP, it travels over T1 lines,
microwave stations, earth-based
stations, and communications satellites
until it reaches the Internet backbone.
Step 3. The request travels over T3
lines along the Internet backbone.
Step 4. The Request travels over T1 lines
until it reaches the destination network server.

43. Physical Transmission Media
What is physical transmission media?
Nextp. 490 Fig. 9-35
Transfer Rates for Various Types of LANs Using Physical Transmission Media Wire, cable,
and other
tangible
materials used
to send
communications
signals

44. Physical Transmission Media
What are twisted-pair cable and coaxial cable?
Nextp. 490 Fig. 9-36—9-37
 Twisted-pair cable is used for telephone systems and network cabling
 Coaxial cable is often used for cable television wiring

45. Physical Transmission Media
What is fiber-optic cable?
Nextp. 491 Fig. 9-38
 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)

46. Wireless Transmission Media
What is wireless transmission media?
Nextp. 491 Fig. 9-39
 Used when inconvenient, impractical, or impossible to
install cables
 Includes Bluetooth and IrDA

47. Wireless Transmission Media
What are broadcast radio and cellular radio?
Nextp. 492 Fig. 9-40
Click to view Web Link,
click Chapter 9, Click Web Link
from left navigation,
then click Cellular
Communications
below Chapter 9
 Broadcast radio
distributes radio
signals over long
and short distances
 Cellular radio
is form of
broadcast radio
used for mobile
communications

48. Wireless Transmission Media
What is a microwave station?
Nextp. 493 Fig. 9-41
 Earth-based
reflective
dish used for
microwave
communications
 Must transmit in
straight line with
no obstructions

49. Wireless Transmission Media
What is a communications satellite?
Nextp. 494 Fig. 9-42
 Space station
that receives
microwave signals
from earth-based
station, amplifies
signals, and
broadcasts signals
back to any number
of earth-based
stations

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