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Telecommunications, the Internet,
Intranets, and Extranets
Chapter 4
Fundamentals of Information
Systems, Second Edition
1
Learning Objectives
– Define the term telecommunications and
identify and describe the function of the
components of a telecommunications system.
– Identify and briefly describe three basic data
processing strategies, including their
advantages and disadvantages.
Fundamentals of Information
Systems, Second Edition
2
Learning Objectives
– Briefly describe how the Internet works,
including alternatives for connecting to it and
the role of Internet service providers.
– Identify and briefly describe common Internet
services.
Fundamentals of Information
Systems, Second Edition
3
Learning Objectives
– Describe the World Wide Web and the way it
works, including the use of Web browsers,
search engines, Java, and other Web tools.
– Define the terms intranet and extranet and
discuss how organizations are using them.
– Identify several control and management
issues associated with the use of networks.
Fundamentals of Information
Systems, Second Edition
4
Telecommunication
– Electronic transmission of signals for
communications
– Telecommunications device is a hardware
component that allows electronic
communication to occur
– Telecommunications medium carries an
electronic signal and interfaces between a
sending device and a receiving device
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Systems, Second Edition
5
Elements of a Telecommunications
System
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Systems, Second Edition
6
Media Types (1)
– Twisted-pair wire cable: Twisted pairs of copper wire
• Used in telephone service
• Slow transmission
– Coaxial cable: Conductor wire is insulated
• Faster than twisted-pair
– Fiber-optic cable: Thin strands of glass bound
together
• Uses light beams
• Faster than coaxial cable
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Systems, Second Edition
7
Media Types (2)
– Microwave transmission: High-frequency
radio signal
• Must have unobstructed line of sight between
sender and receiver
• Possible to intervene
– Cellular transmission: Divide area into cells
• Each cell has a mobile telephone subscriber unit
• Possible to intervene
– Infrared transmission: Signals as light waves
Fundamentals of Information
Systems, Second Edition
8
Common Wiring and Cabling Types
Fundamentals of Information
Systems, Second Edition
9
Common Telecommunications Devices
– Modem: Translates data from digital form into
analog form (for ordinary phones) and back
• MOdulation and DEModulation
– Fax modem: Facsimile device but also a
modem
– Multiplexer: Allow several signals to be
transmitted over the same line
– PBX: Manages both voice and data transfer
• Switching equipment routes phone calls and
messages within the building
Fundamentals of Information
Systems, Second Edition
10
Carriers and Services
• Common carriers: Turk Telecom, AT&T
• Switched lines
– Use switching equipment to connect one phone to
another
– Switch: Special purpose circuit that directs messages
in certain directions
• Digital subscriber lines (DSL)
– Use existing lines to transmit signals over 500Kbps
– Faster Internet access
Fundamentals of Information
Systems, Second Edition
11
Costs, Advantages, and Disadvantages of
Several Line and Service Types
Line/Service
Speed
Cost per
month
Advantages
Disadvantages
Standard
phone line
56Kbps
$10-40
Broadly
available
Too slow
ISDN
64-128Kbps
$50-150
Faster
Not available
everywhere
DSL
500Kbps1.5Mbps
$20-120
Use standard Expensive; not
line
available ew.
Cable
modem
500Kbps1.5Mbps
$20-120
Use existing
cable
T1
1.544 Mbps
$600-1200 FAST; used by
“”
EXPENSIVE
corporations
Satellite
60-800Kps
$30-120
Instead of
cable or DSL
Fundamentals of Information
Systems, Second Edition
Expensive
installation
12
Networks and Distributed Processing
• Computer network - communications media, devices, and software
needed to connect two or more computer systems.
• Centralized processing - processing occurs in a single location or
facility.
• Decentralized processing - processing devices are placed at
various locations.
• Distributed processing - computers are placed at remote locations
but are connected to each other via telecommunications devices.
Fundamentals of Information
Systems, Second Edition
13
Terminal-to-Host Connection
• Host computer has the data and the processing
power
• Dumb terminal contacts host computer for jobs
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Systems, Second Edition
14
File Server Connection
• The application and database reside in host
computer.
• Files transferred as a whole and processed by
the user
Fundamentals of Information
Systems, Second Edition
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Client/Server Connection
• Servers have special functionalities (database
server, program execution, etc.)
• Clients request services from servers
• Clients process service results
Fundamentals of Information
Systems, Second Edition
16
Network Types
• Local area network (LAN)
– Same geographic area
– Wired into office buildings (unshielded twisted-pair)
• Wide area network (WAN)
– Microwave and satellite transmission
– Long-distance calls
• International network
– Transborder data flow
– International laws
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Systems, Second Edition
17
A Typical LAN
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Systems, Second Edition
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A Wide Area Network
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Systems, Second Edition
19
Connecting Computing Devices Using a Home
Network
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Systems, Second Edition
20
Communications Software and
Protocols
• Communications software - provides a number of
important functions in a network
• Network operating system - controls the computer
systems and devices on a network and allows them to
communicate with each other
• Network management software - a manager can
monitor the use of individual computers and shared
hardware
• Communications protocol - rules and standards that
make communications possible
Fundamentals of Information
Systems, Second Edition
21
Common Communications Protocols
Protocol
Description
Open Systems Interconnection
(OSI)
Divides data communication into
seven layers for maintenance
Transport control
protocol/Internet Protocol
(TCP/IP)
Primary communication protocol of
the Internet
Ethernet
Used in LANs
Asynchronous transfer mode
(ATM)
Organizes data into 53-byte cells for
fast transmission
802.11a
Supports wireless ATM devices
Bluetooth
Wireless communication for cell
phones, handheld computers
802.11b (Wi-fi)
Fundamentals of Information
Systems, Second Edition
22
Use and Functioning of the
Internet
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Systems, Second Edition
23
Routing Messages Over the Internet
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Systems, Second Edition
24
How the Internet Works
• Internet Protocol (IP): Set of rules to pass
packets from one computer to another
• Transport Control Protocol (TCP): Set of
rules to establish and break connections
• Internet Protocol Address: Unique address
for each computer on the Internet
• Static vs. dynamic
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Systems, Second Edition
25
U.S. Top-Level Domain Affiliations
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Systems, Second Edition
26
Three Ways to Access the Internet
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Systems, Second Edition
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Internet Service Providers
• Organizations that provide access to the
Internet
• Choose based on price, reliability, other
features (e-mail address)
• Examples: Superonline, E-kolay
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Systems, Second Edition
28
Internet and
Telecommunications Services
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Systems, Second Edition
29
Summary of Internet Services (1)
•
•
•
•
•
•
•
E-mail
Instant messaging
Telnet/SSH
FTP
Chat rooms
Internet phone
Internet video conferencing
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Systems, Second Edition
30
Summary of Internet Services (2)
•
•
•
•
Shop on the Web:
Auctions: http://www.gittigidiyor.com/
Distance learning
Music, radio on the Internet
Fundamentals of Information
Systems, Second Edition
31
Common Abbreviations Used in Personal
E-Mail
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Systems, Second Edition
32
Two Approaches to Electronic Data
Interchange
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Systems, Second Edition
33
Public Network and Specialized Services
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Systems, Second Edition
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The World Wide Web
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Systems, Second Edition
35
The World Wide Web
An Internet service comprising tens of thousands
of independently owned computers that work
together as one.
– Home page: Cover page with text and graphics
– Hypertext markup language (HTML): Standard
language to describe Web pages
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Systems, Second Edition
36
Several Interesting Web Sites
Fundamentals of Information
Systems, Second Edition
37
Sample HTML
Fundamentals of Information
Systems, Second Edition
38
Search Engine
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Systems, Second Edition
39
Intranets and Extranets
Fundamentals of Information
Systems, Second Edition
40
Intranets and Extranets
• Intranet – an internal corporate network built using
Internet and WWW standards and products
• Extranet - a network that links selected resources of the
intranet of a company with its customers, suppliers, or
other business partners
• Virtual private network - a secure connection between
two points across the Internet
• Firewall - a device that sits between your internal
network and the outside Internet
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Systems, Second Edition
41
Summary of Internet, Intranet, and
Extranet Users
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Systems, Second Edition
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Virtual Private Network
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Systems, Second Edition
43
Net Issues
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Systems, Second Edition
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Privacy and Security
• Cookie: Text that is put on user computer to
track Web site usage
• Cryptography: Converting a message into a
secret code and then back into the message
• Encryption
• Digital Signature: Who sent the message, did
the message change on the way?
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Systems, Second Edition
45
Cryptography
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Systems, Second Edition
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Summary
• Networks - used to share hardware, programs,
and databases across the organization.
• Internet - transmits data from one computer
(called a host) to another.
• The Web - a collection of tens of thousands of
independently owned computers that work
together as one in an Internet service.
Fundamentals of Information
Systems, Second Edition
47
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