networking and telecommunications 9. 2001 prentice hall9.2 chapter outline linking up: network...
Post on 21-Dec-2015
217 views
TRANSCRIPT
2001 Prentice Hall 9.2
Chapter Outline
• Linking Up: Network Basics
• Electronic Mail, Teleconferences, and Instant Messages: Interpersonal Computing
• Converging Communication Technologies: From Messages to Money
“Any sufficiently advanced technology is indistinguishable from magic.”
Arthur C. Clarke
2001 Prentice Hall 9.3
Linking Up: Network Basics
• Cost– allows people to share hardware
• Efficiency & Productivity– allows people to share data and software
• Opportunity– allows people to work together in ways
that are otherwise difficult or impossible
Why is networking important?
2001 Prentice Hall 9.4
Basic Network Anatomy
• A computer network is anycomputer system that linkstwo or more computers
• There are three essentialcomponents in a network:
– Hardware
– Software
– People
2001 Prentice Hall 9.5
The Network Interface
• A Network Interface Card (NIC):– Is needed to connect directly to a
network
– Adds an additional port to the computer
– Controls the flow of data between the computer’s RAM and the network cable
– Converts the computer’s digital signals into the type required for the particular network
2001 Prentice Hall 9.6
• A modem is needed to connect a computer to a phone line
Communication á la Modem
• The computer communicates with digital signals
• The telephone system was designed to transmit voice signals, which are analog
2001 Prentice Hall 9.7
aa
Terminal
Modem
Modem
Analogsignals
Phone line
Digitalsignals
Digitalsignals
Computer
The word modem comes from theterms modulation and demodulation
How a Modem Works
ModulationDemodulation
2001 Prentice Hall 9.8
A modem:
– Converts the digital stream of information from a computer to an analog stream in order to send a message on the telephone network
Communication á la Modem
2001 Prentice Hall 9.9
A modem:
– Converts the analog stream of information received over the telephone network into the digital form that the computer understands
Communication á la Modem
2001 Prentice Hall 9.10
WAN(Wide Area Network)
LAN(Local Area Network)
Networks Near and Far
There are two general types of computer networks:
2001 Prentice Hall 9.11
LAN (Local Area Network)
A LAN is a network in which the computers are physically close to each other
– They typically share peripherals (printers and servers)
– Each computer and shared peripheral isa node on the LAN
2001 Prentice Hall 9.12
A WAN is a network in which the computers are a great distance from one another
WAN (Wide Area Network)
– Connections are made via telephone lines, satellites, and/or microwave relay towers
– Each network site is a node
2001 Prentice Hall 9.14
Communication software includes:
Communication Software
– Software that allows the hardware to interact with various networks
– A network operating system (NOS) which controls information shared between the dedicated server andclient machines
2001 Prentice Hall 9.15
Client/Server Model
Client software sends requests from the user to the server
Server software responds to client requests by providing data
2001 Prentice Hall 9.16
• The peer-to-peer model allows every computer on the network to be both client and server
Peer-to-Peer Model
• Peer-to-peer networking is built into some operating systems
• Many networks use a hybrid of client/server and peer-to-peer
2001 Prentice Hall 9.17
The Network Advantage
Networks allow people to:
– Share computer resources (hardware and software)
– Share data
– Work togetherin new ways
2001 Prentice Hall 9.18
E-Mail, Teleconferences, & IM: Interpersonal Computing
• Electronic mail, teleconferencing, and Instant messaging (IM) allow communication between two or more computer users
• People can communicate in real time or delayed time
2001 Prentice Hall 9.19
Real-Time vs.Delayed Communication
Real-time communication (synchronous):
– participants meet in real time
– participants see each other’s typedmessages as they are typed
– examples: Talk and Chat
2001 Prentice Hall 9.20
Real-Time vs.Delayed Communication
Delayed communication (asynchronous):
– Participants type, post,and read messages attheir convenience
– Participants share an electronic mailboxrelated to the group’spurpose
– Examples: email and Newsgroups
2001 Prentice Hall 9.21
The Postal Alternative
• Speed
• Accessibility
• Facilitates group communication
• Allows messages to be edited and combined with other documents
• Less intrusive than the telephone
2001 Prentice Hall 9.22
Advantages of E-mail and Video/Teleconferencing
• Allows decisions to evolve over time
• Emphasizes the message, not the messenger
• Makes long-distance meetings possible through video and tele-conferencing
2001 Prentice Hall 9.23
Disadvantages of E-mailand Teleconferencing
• Vulnerable to machine errors, human errors, and security breaches
• Can pose a threat to privacy
• Can be faked
2001 Prentice Hall 9.24
Disadvantages of E-mailand Teleconferencing
• Works only if the recipient responds
• Can be overwhelming
• Both filter out many human components of communication
2001 Prentice Hall 9.25
Rules of Thumb: On-line Survival Tips
• Work offline unless you must be connected
• Avoid peak hours
• Let the system simplify and streamline your work
• Store names and addresses in an on-line address book
• Protect your privacy
• Cross-check on-lineinformation sources
• Be aware of the amount of time youspend on-line
• Avoid informationoverload
2001 Prentice Hall 9.26
Converging Communication Technologies:
From Messages to Money
Alternative Technologies:
On-line Information Services • AOL, CompuServe, MSN,
Prodigy
• Members pay a fee for these services
Fax Machines and Modems
“Never in history has distance meant less.”
Alvin Toffler
2001 Prentice Hall 9.27
Alternative Technologies
Voice Mail and Computer Telephony
Global Positioning System
Video Teleconferencing
E-Money
2001 Prentice Hall 9.28
Building Bandwidth
The quality of information transmitted through a communication medium depends upon bandwidth.
– Increased bandwidth means faster transmission speed
– Bandwidth is affected by the amount of network traffic, software protocols, and type of network connection
2001 Prentice Hall 9.29
Fiber Optic Cables
• Fiber optic cables are replacing aging copper lines
• They use light waves to carry information
• They provide data rates over one billion bits per second
• They offer extremely low error rates
2001 Prentice Hall 9.30
Digital Communication Comes Home
Digital communication lines will soon be available in homes. They will provide us:
• Multi-person video phone conversations
• Universal e-mail
• Customized digital newspapers
• Automatic utility metering
• A variety of entertainment options