Transcript Introduction to MIS Chapter 3

Introduction to MIS
Chapter 3
Networks and Telecommunications
Copyright © 1998-2002 by Jerry Post
Introduction to MIS
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Internal
Teamwork
Communication
Scheduling
Sharing
Networks
Internet
External
Suppliers
Customers
Banks
Introduction to MIS
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Outline
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Introduction
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Computers
Media
Connection Devices
Software
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Shared Media
Switched
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Introduction to MIS
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How the Internet Works
Internet 2
Mobile Commerce
Global Telecommunications

Network Structure
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Standards
The Internet

Components of a Network
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Sharing Data
Sharing Hardware
Sharing Software
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Technical Problems
Political Complications
Cultural Issues
Comment
Cases: Specialty Retail
Appendix: Creating Web
Pages
3
Sharing Data: Transactions
Internet
Database Management
System and Web Server
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Sharing Data: Decisions & Searches
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Decisions & searches
Teamwork & joint authorship
Team Document
File Server and Database
Data
and
Tools
Report and
Comments
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Sharing Data: E-mail
Internet
2. Message
transferred to
account on
server.
3. Transferred
via the Internet
to the
destination
account.
1. User creates e-mail message.
Introduction to MIS
4. Message
received when
user checks email.
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Sharing Data: Calendars
Introduction to MIS
8:00
Mgt meeting
8:30
(open)
9:00
Staff meeting
9:30
Staff meeting
10:00
new meeting
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Hardware Sharing
Printers
Storage
Processors
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tape drive
(backup)
Corporate or
external computer
access
Workstations
Shared
Printer
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Server
Files are transferred from workstations to the server.
Software automatically copies files to tapes.
LAN administrator can restore files if needed.
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Packet-Switched Networks
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Data, Voice, Video
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All converted to packets
Packet has data, destination, and source address
Switched services
Sent as packets:
Voice
Packets routed as needed
B
2
Reassembled at destination Chicago
12345
New York
C
A
4
1
E
Atlanta
Dallas
5
Computer
Introduction to MIS
D
3
Sent as packets: A B C D E
9
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Servers
Work stations
Media
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Network Components
Computers
Personal Computer
Cables
Fiber optic
Radio
Infrared
Personal Computer
LAN card
LAN card
Connection devices
Internet
LAN card
Router or Switch
LAN card
Firewall
Server
Introduction to MIS
Shared Printer
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Server Scalability
Server farms distribute
the workload. Add
more computers for
more power.
Sun 10000
Sun 3800
Increasing
performance
within a
product family.
Rack mount
server farm.
Compaq
Sun Ultra 5
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Network Transmission Media
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Electricity
Fiber optics
Radio waves
Fiber Optic Cable
Example:
Long distance phone lines
reflective cladding
Twisted Pair
Example:
Local phone lines
Radio or Micro Waves
Example:
Cellular phones
Coaxial
Example:
Cable TV
antenna
Shield
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Fiber Optics
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Faster
More data
Less magnetic interference
Long stretches without
repeaters
900 copper wires can be
replaced by one fiber
optic line (for telephone
connections).
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http://www.jsc.mil/images/speccht.jpg
ELF
VLF
100
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1K
MF
100K
HF
1M
VHF
10M
UHF
100M
Microwave Optical
1G
10G
Hertz
All waves behave similarly
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LF
Frequency Spectrum
Sound
Radio
Micro
Light
Frequency differences
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Amount of data
Distance
Interference / Noise
http://www.ntia.doc.gov/osmhome/allochrt.pdf
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Transmission Capacity
Name
10Base-T
100Base-T
Gigabit Ethernet
Wireless LAN
Wireless LAN future
LAN/fiber FDDI
LAN/fiber ATM
LAN/fiber future
Name
Dial-up
DSL
Cable modem
Satellite
Wireless
Wireless/future
T1-lease
T3-lease
ATM
OC-3
OC-12
OC-48
OC-192/future
Introduction to MIS
Local Area Networks
Format
Speed (mbps)
Twisted pair
10
Twisted pair
100
Twisted pair
1000
Wireless
11
Wireless
54
Fiber optic
100
Fiber optic
155
Fiber optic
10,000
Internet Connections
Format
Speed (mbps)
Twisted pair
0.05
Twisted pair
1.5 down/0.13 up
Coaxial
1.5 down/0.26 up
Microwave
1.5 down/0.05 up
Microwave
1.5
Microwave
20-50
Twisted pair
1.544
Fiber optic
45
Fiber optic
155
Fiber optic
155
Fiber optic
622
Fiber optic
2,500
Fiber optic
10,000
Estimated Cost
$20/month
$50/month
$50/month
$50/month
$70/month
$2000/month
$10,000/month
negotiable
A thin fiber optic cable can carry as much data as
900 single copper wires, with minimal
interference, and superior tensile strength.
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The Importance of Bandwidth
Bytes
Bits
Dial-up 50 kbps
DSL 1.5 mbps
LAN 10 mbps
LAN 100 mbps
Gigabit 1 gbps
Introduction to MIS
Text
10,000
80,000
1.6
0.05
0.008
0.0008
0.00008
Image
500,000
4,000,000
seconds
80
2.67
0.4
0.04
0.004
Video-10 sec
15,000,000
120,000,000
2400
80
12
1.2
0.12
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Shared Connections
With shared connections, machines have to take turns, and congestion
can slow down all connections.
With switched
connections, each
computer has the full
bandwidth of the
connection at all times.
Performance depends on
how fast the switch can
handle connections.
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Time Division
A
B
A
C
C
A
C
A time
D
Computers A and B split their messages into packets and share
the transmission medium by taking turns sending the data.
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A
B
frequency
Frequency Division
A
3500 Hz
C
C
D
Computers A and B split the frequency: A uses a higher spectrum.
By listening only to the assigned frequency, multiple transmissions
can occur at the same time.
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A
B
C
D
frequency
Spread Spectrum
time
Sharing a medium by both frequency and time is one method
of spread spectrum transmission. It is efficient for many computers
because the full bandwidth can be utilized over time and frequency.
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Wireless
Communication
Microwave transmissions are
used to provide communications
for cellular phones and laptop
computers. As prices of phones,
portable computers, and
communication costs decrease,
increasing numbers of workers
are choosing wireless
technologies.
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The need for standards
A changing environment
Connecting Networks
Internet
Backbone fiber optic
Routers or Switches
Switch
Hub
Hub
Radio-based network
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Shared-Media Network
Tap
Introduction to MIS
Shared Media
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Switched Network
Switch
Servers
Workstations/PCs
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Enterprise Network
Building 1
Building 2
Fiber optic
Switch
Servers
Firewall
Workstations/PCs
Internet – ISP
Subsidiary
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TCP/IP Reference Model
4. Application
Message
3. Transport (TCP)
2. Internet (IP)
1. Physical
Header 1
Introduction to MIS
Header 3
Message
Trailer 3
Header 2
Header 3
Message
Trailer 3
Trailer 2
Header 2
Header 3
Message
Trailer 3
Trailer 2
Trailer 1
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TCP/IP Reference
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Application
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Transport
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Packetize data and handle lost packets
Establish connections through numbered ports
Internet Protocol (IP)
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Mail, Web, FTP
Authentication, compression, user services
Route packets to destination
Requires unique host addresses: IPv4=32-bit; IPv6=128-bit
Requires standards and cooperation
Subnet
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Physical connections
Transfers bits with some form of error correction
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Introduction to the Internet
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No control
Services
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Mail
Telnet
FTP
WWW
WEB searching
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The Internet
AltaVista
HotBot
Lycos
WebCrawler
Yahoo
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How the Internet Works
Network
service
provider (NSP)
T1: 1.544 Mbps
T3: 44.736 Mbps
OC3: 155.52 Mbps
OC12: 622 Mbps
Backbone
network
Internet
service
provider (ISP)
Phone
company
Individual
Introduction to MIS
Cable
company
Phone
company
Dial-up: 33.3 - 56 Kbps
ISDN: 128 Kbps
DSL: 256 Kbps - 6 Mbps
Cable: 1 to 10 Mbps
Company
Web site
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Backbone providers
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AT&T
GTE
Worldcom/MCI
Sprint
Qwest
Network service providers
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1998: 39
AGIS
AT&T
Cable & Wireless
IBM
MCI/Worldcom
Qwest
Sprint
UUNet
Internet Connections
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Phone companies
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Cable companies
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Direct Satellite
Starband
Internet service providers
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Introduction to MIS
AT&T
Cablevision
Regional.
Satellite
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Regional Bell operating
companies (RBOCs) (6)
Competitive local exchange
carriers (CLECs) (new)
America Online
Microsoft Network
Earthlink
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M-Commerce
Internet access
everywhere
Cell phones
PDAs
Laptops
Great potential
Limited usability
Better than voice?
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Cell Phones and Wireless Communication
Wireless cells work by
handing off the wireless
connection to the next tower
as the caller moves.
Connections to multiple
towers at one time enables
the system to triangulate to
get a fairly precise location
of the cellular device--even
when it is not in a call.
Location knowledge will
make it possible (although
perhaps not desirable) to
offer new business
opportunities as people
move into range.
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Global Telecommunications
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Technical problems
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Political complications
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Multiple standards
Language
Developing nations
Time zones
Limits to space & waves
Transborder data flows
Taxes
Privacy
Accessibility
Cultural issues
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What is an object?
Management & control
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Cases: Specialty Retail
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Cases: Ben & Jerry’s
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Appendix: Creating Web Pages
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Determine the content.
Define a style.
Create each page.
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Text
Graphics
Link the pages.
Test your work.
Transfer pages to a Web site.
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Appendix: Style Sheets
BODY {
margin-left: 5px;
font: 10pt "Times New Roman", Times, serif;
color: black;
Style Sheet
text-align: left;
background-color: #e0ffff;
Body { … }
}
P {…}
P {
margin-left: 0px;
font: 10pt "Times New Roman", Times, serif;
color: black;
background: transparent;
}
H1 {
margin-left: 0px;
font: 16pt "Times New Roman", Times,
color: black;
font-weight: bold;
background: transparent;
}
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Page 2
serif;
Page1
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<HTML>
Appendix: Sample HTML
<HEAD>
<TITLE>Sample HTML Page</TITLE>
</HEAD>
<BODY>
<H1>Section One</H1>
<P>This is a sample paragraph on a
sample page.</P>
</BODY>
</HTML>
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Appendix: Publishing Files
Accessible
Web
pages
Initial
pages
Internet or
intranet
Web server
Transfer methods:
Microsoft Front Page extensions
Your computer
Introduction to MIS
FTP: file transfer protocol
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Web Development Hints
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Start with a tool like Microsoft Word (or Front Page, etc.).
Get a good graphics package
Keep page size small
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First develop the pages on your own computer.
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Test all links.
Transfer later.
Use style sheets.
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30,000 - 50,000 bytes typically takes 8 - 15 seconds
Consistency.
Ease of change.
Study design elements and art.
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Formal training/art classes.
Study other sites.
Watch for and create trends.
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