Transcript 9 chapter communications and networks

9
COMMUNICATIONS
AND NETWORKS
9-2
Competencies
Discuss connectivity, the wireless revolution,
and communication systems
Describe physical and wireless communications
channels
Discuss connection devices
Describe data transmission factors
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Competencies cont.
Discuss networks and key network terminology
Describe the different types of networks
Describe network architectures
Describe organizational uses of Internet
technologies
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9-4
What is Communication?
The process of sharing data, programs, and
information between two or more computers
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Communications Today
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Cont.
Applications that depend on the Communication Systems: email,
instant messaging, internet telephone and electronic commerce.
Connectivity: is a concept related to using computer networks to
link people and resources.
( you can connect your microcomputer by telephone or other telecommunication link to other computers).
Wireless revolution: Allow devices to communicate with one
another without any physical connection
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Communication Systems
Are electronic systems that transmit data from one location to another
Basic elements of a communication system:
1- Sending and Receiving Devices ( computers or specialized communication devices).
2- Communication Channel( transmission medium) (physical wire or cable
and wireless
connection).
3- Connection Devices (communication devices): Act as an interface between the
sending and receiving devices and the communication channel, they convert outgoing message
into a form and format so that they can travel across the communication channel.
4- Data Transmission specifications: rules and procedures that coordinate the sending and
receiving devices( how the message will be send through the communication channel)
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Communication Systems
Modem
Computer
Telephone-lines
E-mail
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Communication Channels
Channels carry data from one computer to
another
Two categories of communication channels
Physical connection
Wireless connection
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Physical Connections
Solid medium to connect sending and receiving devices
Telephone lines ( twisted pair cable)
Coaxial cable
high frequency transmission cable
deliver television signals and connect computer in a network.
80 times the transmission capacity of twisted pair cable
Fiber-optic cable
Transmit data as pulses of light through tiny tubes of glass.
26000 times the transmission capacity of twisted pair cable
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Wireless Connections
Infrared
Broadcast radio: Communication uses special sending and
receiving towers called Transceivers, send and receive radio
signals from wireless devices
Microwave: Communication uses high frequency radio
waves
sending data between buildings in a city
Stations used for long distance
Bluetooth
Satellite
Uplink/Downlink
Uplink is a term of sending data to a satellite.
Downlink is a term of receiving data from a satellite.
Global Positioning System: Application of satellite
communication
Note: Check page 239
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9-12
More on Satellites
Global positioning
Network of 24 satellites
Owned by the Defense Department
Global positioning system (GPS)
Devices used to determine location
Provides navigational support
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9-13
Connection Devices
Types of signals
Analog
Digital
Types of modems
Internal: plug-in circuit board
External: wall jack, modem and serial port
PC Card: laptop
Wireless
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Types of Connections
Digital subscriber line (DSL)
Uses existing phone lines
ADSL (Asymmetric digital subscriber line)
ADSL services can download at up to 8Mb/s and upload up to
832 kb/s,
Cable modems
Uses existing TV cable
Provides speeds as fast as DSL at a lower cost
Satellite/air connection services
Seven times faster than dial-up
Slower than DSL & cable modem
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9-15
User Connection Costs & Speeds
Type
Fee
Speed
Seconds to Get
Images
Dial-up
$16
56 kbps
45.0
DSL
50
1.5 mbps
1.7
Cable Modem
40
1.5 mbps
1.7
Satellite
70
900 kbps
2.8
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9-16
Bandwidth
Measurement of the capacity of the channel
Categories
Low bandwidths or Voiceband
Used for standard telephone communication
Medium band
Used for minicomputer and mainframe
Broadband
Used for high capacity transmission
Used by DSL, cable & satellite
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Protocols
Set of communication rules
Rules for exchanging data between computers.
Standard for Internet: TCP/IP
Transmission control protocol/Internet protocol
Identifies devices :
Identifying sending and receiving devices
Each computer on the internet has IP address
DNS domain name server convert text to IP address.
Reformats information
Reformatted or broken into small parts called packets
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Networks
A computer network is a communication system
Connects two or more computers
Allows information exchange
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Network Terms
Node
Any device that is connected to a network
(Computer or printer)
Client: microcomputer
Server
A node that shares resources with other nodes
Hub
The center or central node for other nodes
Network interface cards
(NIC)
Network operating
system (NOS)
Distributed processing
This type of system is common in
decentralized organization where
divisional offices have their own computer
Host computer
Minicomputer or mainframe computer
Network manager
Computer specialist or network administrator
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9-20
Network Types
Local area networks 1 mile
Home networks
Including a common internet connection
Metropolitan area networks (MAN)
100 miles connect buildings in a city
Wide area networks(WAN)
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Network Architecture
Architecture describes how a network is
arranged
Arrangement is called topology
Types of network topology
Star
Bus
Ring
Hierarchical
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Star Network
Smaller computers linked
to a central unit
Central unit is called the
network hub
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Bus Network
Each device handles its own communication control
There is no host computer
Has a common connecting cable called a backbone
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Ring Network
Each device is connected
to two other devices
No central file server or
computer
Useful in a decentralized
environment
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Hierarchical Network
Several computers linked
to a central host
Computers are hosts to
other computers
Useful in centralized
organizations
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Strategies
Strategy is a way of coordinating the sharing of information and
resources
Common network strategies
Terminal
Processing power is centralized in one large computer , usually a mainframe
.
Many airline reservation systems are terminal systems. A large central computer maintain
all the airline schedule.
Client/server
Use one computer to coordinate and supply services to other nodes on the network. The
server provides access to resources such as web pages, database.
Peer-to-peer
Nodes have equal authority and can act as both clients and servers, for example one
microcomputer can obtain files located on another microcomputer and can also provide
files to other microcomputers
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Organizational Internets
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Internets and Extranets
Intranets
Private network within an organization
Provides information to employees
Extranets
Private network that connects organizations
Used to allow suppliers and others access
Firewalls
Security system
Protects against external threats
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A Look to the Future
Wireless Robotic Car
Pod car (Personalization on Demand)
Predicts and responds
Designed to learn and adapt to an individual's
driving needs and habits
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Key Terms
802.11 (239)
analog signal (240)
application server (243)
asymmetric digital
subscriber line (ADSL)
(241)
backbone (249)
bandwidth (241)
base station (245)
bits per second (bps)
(240)
Bluetooth (239)
broadcast radio (238)
broadband (242)
bus (249)
bus network (249)
cable modem (241)
cellular phone system
(245)
client (243)
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9-31
Key Terms
client/server network
system (251)
coaxial cable (238)
communications (246)
communication channel
(237)
communication device
(237)
communication server
(243)
communication system
(237)
computer network (243)
connection device (237)
connectivity (236)
database server (243)
data transmission
specification (237)
dedicated server (243)
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Key Terms
demodulation (240)
dial-up service (240)
digital signal (240)
digital subscriber line
(DSL) (241)
dish (239)
Distributed data
processing system (249)
distributed processing
(243)
Domain name server
(DNS) (242)
downlink (239)
external modem (240)
extranet (243)
fiber-optic cable (238)
file server (243)
firewall (253)
Gnutella (252)
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Key Terms
global positioning (239)
global positioning system
(GPS) (239)
hierarchical network
(249)
home network (245)
host computer (243)
hub (243)
hybrid network (249)
infrared (238)
internal modem (240)
intranet (253)
IP address (Internet
Protocol address) (242)
LAN adapter (243)
line of sight
communication (238)
Local area network
(LAN) (244)
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9-34
Key Terms
low bandwidth (241)
medium band (242)
metropolitan area
network (MAN) (245)
microwave (239)
microwave station (239)
modem (240)
modulation (240)
Napster (251)
network administrator
(243)
network architecture
(248)
network gateway (244)
network hub (248)
network interface card
(NIC) (243)
network manager (243)
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Key Terms
network operating
system (NOS) (243)
node (243)
packet (242)
PC card modem (240)
peer-to-peer network
system (252)
polling (248)
printer server (243)
protocol (242)
proxy server (254)
receiving device (237)
regional network (245)
ring network (249)
satellite (239)
Satellite/air connection
service (241)
sending device (237)
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9-36
Key Terms
server (243)
star network (248)
strategy (250)
TCP/IP (transmission
control protocol/Internet
protocol) (242)
telephone line (238)
terminal network system
(250)
time-sharing system
(249)
T1, T2, T3, T4 lines
(240)
topology (248)
transceiver (238)
transfer speed (240)
transfer rate (240)
transmission medium
(237)
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Key Terms
twisted pair (238)
uplink (239)
voiceband (241)
voice grade (241)
Web server (243)
wide area network
(WAN) (245)
Wi-FI (wireless fidelity)
(239)
wireless LAN (WLAN)
(245)
wireless modem (240)
wireless receiver (245)
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FAQs
What is fiber-optic cable?
My Palm Pilot uses Bluetooth. What is it?
What is a modem?
What is DSL? How does it work?
How fast is broadband bandwidth?
What is a local area network?
What is meant by peer-to-peer?
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Discussion Questions
Discuss what is meant by the wireless
revolution.
Discuss the four types of service connections.
Discuss the advantages and disadvantages of the
four network topologies.
Explain the connections in a home network.
Describe the different network topologies.
Describe a GPS system.
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