Chapter 8 Communications and Networks

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Chapter 8 Communications and Networks
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Chapter 8 Objectives
Discuss the components required for successful
communications
Describe various types of lines for
communications over the telephone network
Describe commonly usedcommunications devices
Describe uses of computer communications
Differentiate among types of networks
Discuss different ways to set upa home network
Explain the purpose ofcommunications software
Identify various physical and wireless
transmission media
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Communications

• What are computer communications?

• Process in which two or more computers or devices
  transfer data, instructions, and information

p. 282 Fig. 8-1
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Communications

• What is needed for successful communications?

p. 282
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Uses of Computer Communications

• What are some uses of communications technology?

Web
Internet
E-Mail
InstantMessaging
FTP
Newsgroups
Chat Rooms
WebFolders
Fax Machine or Computer Fax/Modem
VideoConferencing
p. 285 Fig. 8-3
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Uses of Computer Communications

• What are Internet telephony and Internet
  printing?

p. 285
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Uses of Computer Communications

• What are Web services?

• Software that enables programmers to create
  applications that communicate with other remote
  computers

p. 286
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Uses of Computer Communications

• What are collaboration and groupware?

• Collaboration is working with other users
  connected to a server

• Microsoft Office 2003allows collaboration
• Groupware is softwarethat allows peopleto
  shareinformation

p. 286 Fig. 8-4
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Uses of Computer Communications

• What are public Internet access points and
  cybercafés?

• Public Internet access point allows wireless
  connection to Internet in public location
• Cybercafé is coffee house that provides computers
  with Internet access

p. 287 Fig. 8-5
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Uses of Computer Communications

• What is a global positioning system (GPS)?

p. 288 Fig. 8-6
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Uses of Computer Communications

• What are voice mail and wireless messaging
  services?

• Voice mail is voice message converted to digital
  form
• Wireless messaging services include
• Text Messaging
• Instant Messaging
• Picture Messaging

p. 289 Fig. 8-7
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Networks

• What is a network?

• Collection of computers and devices connected via
  communications devices and transmissionmedia

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. 289
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Networks

• What is a wide area network (WAN)?

• Network that covers large geographic area using
  many types of media

• Internet is worlds largest WAN

p. 290 Fig. 8-8
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Networks

• What is a client/server network?

• One or more computers act as server and other
  computers, or clients, access server

p. 291 Fig. 8-9
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Networks

• What is a peer-to-peer network?

• Simple network that connects fewer than 10
  computers

• Each computer, or peer, has equal capabilities

p. 291 Fig. 8-10
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Networks

• What is Internet peer-to-peer (P2P)?

• Enables users to connect to each others hard
  disks and exchange files directly

p. 292 Fig. 8-11
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Networks

• What is network topology?
• Layout of devices in a network
• Popular topologies are bus, ring, and star
• Bus network
• All computers and devices connect to a central
  cable, or bus

p. 292 Fig. 8-12
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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. 293 Fig. 8-13
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Networks

• 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. 293 Fig. 8-14
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Networks

• What are Ethernet and token ring?

• 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
p. 294
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Networks

• What are TCP/IP and 802.11?

• 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

p. 294
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Networks

• What is Bluetooth?

• Short-range radio waves transmitdata between
  Bluetooth devices

p. 294
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Networks

• What are IrDA, RFID, and Wireless Applications
  Protocol (WAP)?

Radio Frequency Identification (RFID) uses
radio signals to communicatewith a tag placed in
an object
IrDAspecification allows data to be transferred
wirelessly via infrared light waves
Wireless Applications Protocol (WAP) allow
wireless mobile devices to access Internet
p. 294
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Networks

• What is an intranet?

p. 295
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Communications Software

• What is communications software?

p. 295
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Communications Over the Telephone Network

• What is the public switched telephone network
  (PSTN)?

• Worldwide telephone system that handles
  voice-oriented telephone calls

p. 296 Fig. 8-15
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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

p. 296
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Communications Over the Telephone Network

• What is a dedicated line?

• Always-on connection between two communications
  devices

• Four types are ISDN line, DSL, T-carrier line,
  and ATM

p. 297 Fig. 8-16
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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

p. 298
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Communications Devices

• What are examples of communications devices?

p. 298
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Communications Devices

• What is a dial-up modem?

• Converts digital signals to analog signals and
  vice versa
• Notebook computers often use PC Card modem

p. 298 Figs. 8-178-18
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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. 300
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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. 300 Fig. 8-19
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Communications Devices

• What is a network card?

• Adapter card, PC Card, or compact flash card that
  enables computer or device to access network

p. 300 Fig. 8-20
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Communications Devices

• What is a wireless access point?

• Central communications device that allows
  computers and devices to transfer data wirelessly
  among themselves or to wired network

p. 301 Fig. 8-21
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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

p. 301 Fig. 8-22
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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
• HomeRF (radio frequency) wireless

p. 302 Fig. 8-23
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Communications Channel

• What is a channel?

• Transmission media on which data travels in
  communications system

Transmission media are materials capable of
carrying one or more signals
Bandwidth is amount of data that can travel over
channel
p. 303
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Communications Channel

• How is a request sent over the Internet using a
  communications channel?

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.
p. 304 Fig. 8-24
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Physical Transmission Media

• What is physical transmission media?

• Wire, cable, and other tangible materials used
  to send communications signals

p. 305
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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. 305 Fig. 8-258-26
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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)

p. 306 Fig. 8-27
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Wireless Transmission Media

• What is wireless transmission media?

• Used when inconvenient, impractical, or
  impossible to install cables
• Includes infrared, broadcast radio, cellular
  radio, microwaves, and communications satellites

p. 306
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Wireless Transmission Media

• What are broadcast radio and cellular radio?

• Broadcast radio distributes radio signals over
  long and short distances

• Cellular radio is form of broadcast radio used
  for mobile communications
• A cellular telephone is a telephone device that
  uses high-frequency radio waves to transmit voice
  and digital data messages

p. 306
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Wireless Transmission Media

• What is a microwave station?

• Earth-based reflective dish used for microwave
  communications

• Must transmit in straight line with no
  obstructions

p. 307
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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

p. 307
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Summary of Communications and Networks
Communications terminology and applications
Various communications devices, media, and
procedures
How to join computers into a network
Chapter 8 Complete