Transcript Chapter 5

Telecommunications, Networks, and
the Internet
Chapter Eight (9th ed)
Chapter 8 and Our Questions
 5. What is the role of the Internet and
networking technology in modern organizations?
 Discuss networking concepts, components,
capabilities, and trends
 Distinguish among internets, intranets,
extranets
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Telecommunications and Networking
in Today’s Business World
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Prior to 1990 most business communication
 Postal service
 Telephone system (voice & fax)
Today most business communication is
 Computers and email using the Internet
 Cellular telephones
 Mobile computers using wireless connections
All business has become “e-business”
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Magnitude of the Change
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1 billion instant messages per day
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4 billion e-mails each day
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65 million music files downloaded
Estimated 3.9 billion photos sent over the
Internet
$769 billion spent in the United States on
telecommunications equipment and services
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Telecommunications spending in the
United States, 2002–2007
Note differences between services and equipment spending
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The Business Telecommunications
Environment
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Today’s telecommunications environment
provides communication channels for text, voice,
and video images.
Today the network infrastructure for a large
corporation consists of different kinds of
networks for text, voice, and video images.
Most of these different kinds of networks are
moving towards a common Internet foundation.
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Corporate Network Infrastructure
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Pieces in the Corporate Infrastructure
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Center piece is a collection of linked LANS that
support a firm wide corporate network
A series of servers supporting a corporate web
site linked to enterprise and legacy systems
Support for a mobile sales force
Separate telephone network (cell and landline)
Separate video conferencing system (not shown)
Currently no one vendor can supply all of the
services required
How does a manager navigate through this
complex environment and make the right
decisions?
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Seven Major Trends In
Telecommunications
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Proliferation of new hardware and new alternatives for
business communications (Internet cell phones and
wireless LANS)
Telecom deregulation continues to encourage competition
and alternatives (e.g., DSL)
Distinctions between telephone, cable television, Internet,
and satellite telecommunication are blurred.
Growing dominance of Internet technologies in voice,
video, and data communications
Rapid growth in “last-mile” high-speed broadband
connections to homes and businesses
Rapid growth in wireless telephone, wireless computer
networks, and mobile Internet devices
Growing scope of communication-intense services and
products (Internet telephone and telephone photography)
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Why Is Business Interested in
Telecommunication and Networking?
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Declining transaction costs (benefits of B2C and
B2B)
Declining agency costs because managers can
monitor employees and markets remotely
Increased agility (connections with suppliers and
customers enables managers to spot trends and
take appropriate actions). Concepts like
extranets, collaborative commerce, intranets
support this idea.
Higher quality management decisions (access to
more information in a timely manner)
Declining geographical barriers
Declining temporal barriers (software
development, time-based competition)
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Key Networking Infrastructure
Components
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Basics – NIC, NOS, hub, switch, and router
Client/Server computing
Packet switching
TCP/IP
Signal types
Transmission speeds
Transmission media – wire or wireless
Types of networks – geographic scope or shape
High-speed transmission technologies
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Basic Network Components
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A network consists of two or more connected
computers.
A network interface device (NIC) is the
connection point between one computer and the
network
A network operating system (NOS) routes and
manages communications on the network and
coordinates network resources (saving or
retrieving files on your hard drive versus a
network drive)
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Basic Network Components
(continued)
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Hubs connect network components, sending a
packet of data to all other connected devices
A switch has more intelligence than a hub and can
forward data to a specified device or destination.
The switch is used within a given network to
move information.
Unlike a switch, a router (bridge) is a special
communications processor used to route packets
of data through different networks, ensuring that
the message sent gets to the correct address. A
router connects a LAN to the Internet.
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A Simple Network
Figure 8-4
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Client/Server Computing
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The hardware side
 The client
 The server
The software side
 Client/server software splits the processing of
applications between the client and server to
take advantage of strengths of each machine
 E-mail and browsers are examples
Client/server computing has largely replaced
centralized mainframe computing
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Packet Switching
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In packet-switched networks, messages are first
broken down into small bundles of data called
packets that are sent along different
communication paths and then reassembled once
they reach their destinations.
Packet switching makes more efficient use of the
communications capacity of a network.
The packets include information for directing the
packet to the right address and for checking
transmission errors along with the data.
Always done on the Internet, but restricted to
data now being used for voice (VoIP)
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Packet Switching
Figure 8-5
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TCP/IP
• TCP/IP is the communications protocol used by
the Internet and all Internet devices.
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TCP part
 Handles the movement of data between
computers
 Establishes a connection between the
computers, sequences the transfer of packets,
and acknowledges the packets sent
IP part
 Responsible for the delivery of packets
 Includes the disassembling and reassembling
of packets during transmission
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Data and Signals
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Digital data (1’s and 0’s) are represented by a
discrete non-continuous wave form.
Analog data is represented by a continuous wave
form. The human voice, music, and noise are
examples of analog data.
From a physical point of view, data can converted
to an electric (carried over a wire) or
electromagnetic (stream of photons) signal
Usually digital signals convey digital data and
analog signals convey analog data.
In telecommunications there is a need to convert
digital data to an analog signal and vice versa.
Computers emit digital data but parts of the
telephone system only transmit analog signals, so
digital data must be converted into an analog
signal and vice versa (need for your modem)
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More on Signals
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All signals can be represented as a sine wave (curve).
The amplitude of a sine wave is the maximum height of the
sine wave from the x-axis
The frequency of a sine wave is the number of times a sine
wave makes a complete cycle within a given time frame.
Cycles per second is referred to as Hertz (Hz)
Digital data can be converted to a digital signal by using
two different voltages.
Digital data can be converted to an analog signal by using
either two different frequencies or two different
amplitudes.
The greater the frequency of a signal, the higher the
possible data transfer rate; the higher the desired data
transfer rate, the greater the need signal frequency.
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Electromagnetic Signals
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Electromagnetic signals can be described in terms
of a stream of photons each traveling in a wavelike pattern, moving at the speed of light and
carrying some amount of energy. The only
difference between radio waves, visible light, and
gamma-rays is the energy of the photons. Radio
waves have photons with low energies,
microwaves have a little more energy than radio
waves, infrared has still more, then visible, Xrays, and gamma-rays. Low energy photons (such
as radio) behave more like waves, while higher
energy photons (such as X-rays) behave more like
particles.
The electromagnetic spectrum can be expressed
in terms of energy, wavelength, or frequency.
Each way of thinking about the EM spectrum is
related to the others in a precise mathematical
way (see next slide).
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The Relationship Between Wave
Length and Frequency
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Modulation
Figure 6.8 Signal modulation
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Frequency Spectrum for
Electromagnetic Signals
ELF
VLF
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LF
1K
MF
100K
HF
1M1M
VHF
10M
UHF
100M
Microwave Optical
1G
Hertz
10G
All waves behave
similarly
Frequency differences
 Amount of data
 Distance
 Interference /
Noise
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Transmission Speeds
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Digital signal speeds are usually expressed in bits
per second (Kbps, Mbps, and Gbps).
Analog signal speeds are usually expressed in
frequency per second or Hertz (KHz, MHz, or
GHz).
A simple relationship between bps and frequency
is found in Nyquist’s theorem
 C=2*f*(log2)*L where f is the frequency, L is
the number of signal levels (often 2) and C is
the capacity of the medium in bps
The range of frequencies accommodated on a
particular medium is called its bandwidth. For
example, current cell phones operate in a
bandwidth between 1.85 GHz and 2.2 GHz
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Transmission Media – Wire Or Wireless
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Wire media
 Twisted Wire – up to 100Mbps
 Coaxial Cable – up to 1 Gbps
 Fiber Optics – up to 6+Tbps
 Uses strands of glass and pulses of light
 Most expansive of three – can carry data,
voice, and video efficiently
Wireless media
 Terrestrial microwave 100 +Mbps
 Satellite microwave GEO (geostationary earth
orbit); about 22,000 miles above earth
 Satellite microwave LEO (low earth orbit);
about 400-1000 miles above earth
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Multiplexing Concept
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Multiplexing involves using a single
communications channel to carry simultaneous
transmissions from multiple sources.
Examples
 Frequency division multiplexing divides a high
speed channel into multiple channels of slower
speeds
 Time division multiplexing assigns the sender
transmitter a small slice of time to use the high
speed channel
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Types of Networks by Geographic
Scope
Type
Local Area Network (LAN)
Campus Area Network (CAN)
Metropolitan Area Network
(MAN)
Wide Area Network (WAN)
Area
Up to 500 meters (half a mile); an
office or floor of a building
Up to 1,000 meters (a mile); a college
campus or corporate facility
A city or metropolitan area
Transcontinental or global area
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LANs
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Typical LAN operating systems are Windows (based), Linux,
or Novell each supports TCP/IP (ease of establishing an
intranet)
Ethernet is a LAN standard contained on the NIC
LANs may use the client-server or peer-to-peer architecture
(all computers can share resources directly)
In the client-server model
 NOS is primarily on the server
 Large LANs often have many servers each dedicated to a
specific function (e.g., print server, file server, Web
server)
LAN topologies (shapes)
 Star
 Bus
 Ring
Wired LANs versus wireless LANs
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LAN Topologies
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Unique Features of the Internet
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The Internet Addressing System
Every device connected to the Internet has a unique
32-bit numeric IP address.
A Domain Name System (DNS) converts IP
addresses to English-like domain names.
 The domain name is the name that corresponds
to the unique 32-bit numeric IP address for
each computer connected to the Internet.
 DNS servers maintain a database containing IP
addresses mapped to their corresponding
domain names.
To access a computer on the Internet, users need
only specify its domain name.
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Limitations on the Addressing System
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Internet Protocol version 4 (IPv4): A 32-bit string
of numbers organized into four sets of numbers
ranging from 0 to 255; contains up to 4 billion
addresses
Internet Protocol version 6 (IPv6): 128-bit
addresses, contains over a quadrillion possible
unique addresses
Internet2 and Next-Generation Internet (NGI)
are consortia working on the next generation
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Internet Governance
• No one “owns” the Internet, but worldwide
Internet policies are established by the
following organizations:
Internet Architecture Board (IAB)
 Internet Corporation for Assigned Names
and Numbers (ICANN)
 Internet Network Information Center
(InterNIC)
 Internet Engineering Steering Group (IESG)
 Internet Engineering Task Force (IETF)
 Internet Society (ISOC)
 World Wide Web Consortium (W3C)
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Internet Technologies with Business
Implications
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Chatting and instant messaging
Electronic discussion groups
Groupware
Electronic conferencing
Internet telephony
Virtual private networks
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Management Opportunities
• Firms have opportunities to radically reduce the
cost of communicating with their employees,
vendors, and customers. There are many new
opportunities to develop new business models
based on the new telecommunications
technologies.
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Management Challenges
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Loss of management control
 Distributed resources are harder to control
 Employees have independent sources of
computing power
 Use of technology for non-business purposes
Organizational changes must take place as firms
embrace new technologies
 Polices for handling data
Reliability and security
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