Chapter 8 Communications and Networks

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Chapter 8 Communications and Networks
2
Computer Communications
Fig. 8-1
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Communications

• What is needed for successful communications?

p. 296
4
Uses of Computer Communications

• Web
• RSS
• E-Mail
• .
• Dont forget business applications

p. 298
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Uses of Computer Communications

• Wireless Messaging Services
• Text messaging (SMS)
• Wireless IM
• Picture/video messaging (MMS)
• Above can be mobile to mobile mobile to PC

p. 298 - 299
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Uses of Computer Communications

• Wireless (Internet) Access Points
• Hot Spot
• Wi-Fi card (802.11) in laptop
• 3G Network
• Uses cellular technology
• Use cell phone or
• Laptop with card/modem
• Cybercafés

7
Uses of Computer Communications

• Global positioning system (GPS)

Fig. 8-5
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Uses of Computer Communications

• Collaboration and Groupware?
• Collaboration is working with other users
  electronically
• Work on documents via electronic meeting
• Document management system
• Groupware
• Calendar

Fig. 8-6
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Networks

• Network .
• Local Area Network (LAN)
• WC244-D
• Wired/Wireless
• Metropolitan Area Network (MAN)
• Wide Area Network (WAN)

p. 303 - 304
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Networks - LAN

• Client/server network
• (File) Server
• Shared data
• Network printer
• Clients

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Networks - WLAN

• Wireless access point
• Wi-Fi card (802.11) in computers
• Advantage?

Fig. 8-9
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Networks

• Peer-to-peer network?
• Each computer peer
• Fewer than 10 computers

Fig. 8-10
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WAN
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Networks

• Internet peer-to-peer (P2P)
• Users connect to each others hard disks
• Kazaa, BitTorrent, Gnutella

Fig. 8-11
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Networks

• Network topology
• Layout of devices in a network
• Bus, ring, and star
• Bus network

Fig. 8-12
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Networks

• Ring network
• Cable forms closed loop, with all computers and
  devices arranged along ring
• Unidirectional

Fig. 8-13
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Networks

• Star network
• Central device, called hub
• User-proof
• Used by 100 Mbps Ethernet (IEEE 802.3u)

Fig. 8-14
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Networks

• Intranet and Extranet

p. 307 - 308
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Networks LAN Standards

• Ethernet (100Mbps)
• IEEE 802.3u
• Star
• Listen to line to see if they can send
• Token Ring (old)
• IEEE 802.5
• Star
• Need Token to send data

p. 308
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Networks

• TCP/IP
• Transmission Control Protocol/Internet Protocol
• Packet-switched network (Internet)
• 802.11 (Wi-Fi)
• Wireless LANs
• Bluetooth
• Radio waves
• 10m

p. 308 - 309
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Communications Over the Telephone Network

• Public Switched Telephone Network (PSTN)
• Dial-up/Analog lines
• Analog modem, 56Kbps
• Integrated Services Digital Network (ISDN)
• Digital
• ISDN modem (128 Kbps)

p. 310 Fig. 8-15
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Communications Over the Telephone Network

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

Fig. 8-16
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Communications Devices

• Digital versus Analog devices
• Digital versus Analog signaling

p. 312 - 313
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Communications Devices

• Dial-up (analog) modem
• Internal/External
• Wired/Wireless
• PC Card modem

Internal Modem
p. 313
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Communications Devices

• Digital Signaling Devices
• ISDN modems
• DSL modems
• Wired
• Wireless
• Cable modems
• Fastest service?

p. 314
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Communications Devices

• Network cards
• Example 802.3u card

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

p. 31
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Communications Devices

• Wireless Access Point
• 802.11g
• PCs have 802.11g card

p. 315
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Communications Devices

• Routers
• Connect networks (NOT computers)
• Route data to other networks, including Internet
• Example route data from a LAN in Denver to one
  in Dublin
• DSL Router?

Fig. 8-21
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Home Networks

• Wired
• Ethernet 802.3u
• Powerline cable
• Phoneline
• Wireless
• HomeRF
• Wi-Fi (802.11g)

Fig. 8-22
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Communications Channel

• 1 or more transmission media
• Bandwidth capacity speed of the system

p. 317 - 318
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Physical Transmission Media

• Twisted-pair cable
• Pairs of wires inside a cable
• Used in telephone systems and networking
• Coaxial cable (coax)
• Single wire with 3 layers of shielding
• TV and networking

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Physical Transmission Media

• Fiber-optic cable?
• Less susceptible to interference and, therefore,
  more secure
• More secure
• Greater bandwidth

Fig. 8-26
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Wireless Transmission Media

• Electromagnetic waves
• Advantage over cables?
• Includes infrared, broadcast radio, cellular
  radio, microwaves, and communications satellites

p. 320
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Frequency Spectrum
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Wireless Transmission Media

• Infrared and IrDa port
• Broadcast radio (AM, FM)
• Cellular radio is form of broadcast radio

p. 321
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Wireless Transmission Media

• Microwave station
• Earth-based reflective dish used for microwave
  communications
• Obstruction-free path
• Communications satellite (TV broadcasts, GPS)
• Uses high-frequency microwaves
• Receives signal from earth-based station
• Uplink and downlink

p. 321 - 322