Transcript Intro to Information Systems

Chapter 6
Telecommunications and
Networks
McGraw-Hill/Irwin
©2008,The McGraw-Hill Companies, All Rights Reserved
Learning Objectives
1. Understand the concept of a network.
2. Apply Metcalfe’s law in understanding the
value of a network.
3. Identify several major developments and
trends in the industries, technologies, and
business applications of telecommunications
and Internet technologies.
4. Provide examples of the business value of
Internet, intranet, and extranet applications.
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Learning Objectives
5. Identify the basic components, functions, and
types of telecommunications networks used in
business.
6. Explain the functions of major components of
telecommunications network hardware,
software, media, and services.
7. Explain the concept of client/server networking.
8. Understand the two forms of peer-to-peer
networking.
9. Explain the difference between digital and
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analog signals.
Learning Objectives
10.Identify the various transmission media and
topologies used in telecommunications
networks.
11.Understand the fundamentals of wireless
network technologies.
12.Explain the concepts behind TCP/IP.
13.Understand the seven layers of the OSI
network model.
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Network Concepts
• Network
– An interconnected chain, group or system
• Number of possible connections on a network is
N * (N-1)
– Where N = number of nodes (points of connections on
the network)
– Example, if there are 10 computers on a network, there
are 10 * 9 = 90 possible connections
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Metcalfe’s Law
• The usefulness of a network equals the square
of the number of users
• On a small network, a change in technology
affects technology only
• On a large network like the Internet, a change in
technology affects social, political and economic
systems
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Telecommunications
• Telecommunications
– Exchange of information in any form (voice, data, text,
images, audio, video) over networks
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Trends in Telecommunications
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Open Systems
• Information systems that use common standards for
hardware, software, applications and networks
• Internet networking technologies are a common standard
for open systems
• Connectivity:
– Ability of networked computers to easily access and
communicate with each other and share information
• Interoperability:
– The ability of an open system to enable end user applications
to be accomplished using different varieties of computer
systems, software packages, and databases provided by a
variety of interconnected networks
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Middleware
• Any programming that serves to “glue together”
two separate programs
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Digital Network Technologies
• Rapid change from analog to digital network
technologies
• Analog: voice-oriented transmission, sound
waves
• Digital: discrete pulse transmission
• Digital allows:
– Higher transmission speed
– Larger amounts of information
– Greater economy
– Lower error rates
– Multiple forms of communications on same circuit
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Internet2
• Next generation of the Internet
• High-performance network
• In use at 200 universities, scientific institutions,
communications corporations
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Business Value of Telecommunication
Networks
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The Internet
• Over 46 million servers (2004)
• 710 – 945 million users (2004)
• No central computer system
• No governing body
• No one owns it
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Internet Service Provider
• ISP
– A company that specializes in providing easy access to
the Internet
– For a monthly fee, you get software, user name,
password and access
• ISPs are connect to one another through
network access points
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Popular uses of the Internet
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Using the Internet for business
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Business value of the Internet
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An Intranet
• A network inside an organization
– That uses Internet technologies (such as Web browsers
and servers, TCP/IP protocols, HTML, etc.)
– To provide an Internet-like environment within the
organization
– For information sharing, communications, collaboration
and support of business processes
– Protected by security measures
– Can be accessed by authorized users through the
Internet
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Enterprise Information Portal
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Extranet
• Network links that use Internet technologies
– To connect the Intranet of a business
– With the Intranets of its customers, suppliers or other
business partners
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Extranet Uses
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Telecommunications network
• Any arrangement where a sender transmits a
message to a receiver over a channel consisting
of some type of medium
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Telecommunications network
components
• Terminals: any input/output device that uses
networks to transmit or receive data
• Telecommunications Processors: devices that
support data transmission and reception
• Telecommunications Channels: media over
which data are transmitted and received
• Computers: all sizes and types
• Telecommunications Control Software:
programs that control telecommunications
activities
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Telecommunications network model
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Wide Area Network (WAN)
• Telecommunications network that covers a large
geographic area
Source: Courtesy of Cisco Systems
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Local Area Network (LAN)
• Connect computers within a limited physical area
such as an office, classroom, or building
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Virtual Private Networks (VPN)
• A secure network that uses the Internet as
its backbone but relies on firewalls,
encryption and other security
• A pipe traveling through the Internet
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VPN
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Client/Server networks
• Clients: End user personal computers or
networked computers
• Interconnected by LANs
• Servers: manage networks
• Processing shared between clients and
servers
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Client/Server Network
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Network Computing
• Networks are the central computing resource of
the organization
• Thin clients: network computers and other clients
provide a browser-based user interface
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Peer-to-peer networks
• Networks that connect from one PC to another
PC
• Common use is the downloading and trading of
files
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Peer-to-Peer Network
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Telecommunications Media
• Twisted-pair wire:
– Ordinary telephone wire
– Copper wire twisted into
pairs
Source: Phil Degginger/Getty 6Images.
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Telecommunications Media
• Coaxial cable:
– Sturdy copper or
aluminum wire wrapped
with spacers to insulate
and protect it
Source: Ryan McVay/Getty 6Images.
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Telecommunications Media
• Fiber-optic cable:
– One or more hair-thin
filaments of glass fiber
wrapped in a protective
jacket
Source: CMCD/Getty Images.
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Problem of “The Last Mile”
• Network providers use fiber optic to provide
backbone
• But houses are connected to the backbone via
twisted-pair
• Cannot get the benefit of the faster, better
technology
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Wireless Technologies
• Terrestrial microwave
– Earthbound microwave systems that transmit highspeed radio signals in a line-of-sight path
– Between relay systems spaced approximately 30-miles
apart
• Communications satellites
– Satellite serves as relay stations for communications
signals
– Uses microwave radio signals
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Wireless Technologies
• Cellular and PCS telephone and pager systems
– Divide the geographic area into small areas or cells
– Each cell has transmitter or radio relay antenna to send
message from one cell to another
• Wireless LANs
– Radio signals within an office or building
– Connect PCs to networks
• Bluetooth
– Short-range wireless technology
– To connect PC to peripherals such as printer
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Wireless Web
• Connect portable communications devices to the
Internet
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Telecommunications Processors
• Modems
– Convert digital signals from a computer into
– Analog frequencies that can be transmitted over
ordinary telephone lines
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Comparing modem and other
technologies
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Internetwork Processors
• Switch – makes connections between
telecommunications circuits in a network
• Router – intelligent communications processor
that interconnects networks based on different
protocols
• Hub – a port switching communications
processor
• Gateway – connects networks using different
communications architectures
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Communications Processors
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Telecommunications Processors
• Multiplexer
– Allows a single communications channel to carry
simultaneous data transmissions from many terminals
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Telecommunications Software
• Used by servers and other computers to manage
network performance
• Network Operating Systems
• Middleware
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Network management functions
• Traffic Management – manage network resources and
traffic to avoid congestion and optimize service levels to
users
• Security – provide authentication, encryption, firewall,
auditing and enforcement
• Network Monitoring – troubleshoot and watch over the
network, informing network administrators of potential
problems before they occur
• Capacity Planning – survey network resources and traffic
patterns and users’ needs to determine how best to
accommodate the needs of the network as it grows and
changes
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Network Topologies
• Topology: structure of a network
• Star: ties end user computers to a central computer
• Ring: ties local computer processors together in a
ring on a relatively equal basis
• Bus: local processors share the same
communications channel
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Network Topologies
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Network Architectures &
Protocols
• Protocol: standard set of rules and procedures
for the control of communications in a network
• Network Architecture:
– Master plan of standard protocols, hardware, software
and interfaces between end users and computer
systems
– Goal of promoting an open, simple, flexible, and
efficient telecommunications environment
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OSI & TCP/IP Models
• Open Systems Interconnection (OSI) Model
– A seven-layer model that serves as a standard model
for network architectures
– Model for how messages should be transmitted
between two points in a network
– Each layer adds functions
• Transmission Control Protocol / Internet Protocol
(TCP/IP)
– A five layer telecommunications protocol used by the
Internet
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OSI & TCP/IP Models
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Internet Telephony
• Using an Internet connection to pass voice data
using IP
• Voice over IP (VoIP)
• Skips standard long-distance phone charges
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Bandwidth
• Bandwidth
– Frequency range of a telecommunications channel
– Determines transmission rate
– Classified in bits per second (bps)
• Transmission Rates:
– Narrow-band – low-speed
– Broadband – high-speed
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Transmission Speeds
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Switching Alternatives
• Circuit Switching
– Switch opens a circuit to establish a link between a
sender and receiver
– it remains open until the communication session is
completed
• Packet Switching
– Break messages into groups called packets
– Transmit packets separately
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Network Interoperability
• Ensure that anyone anywhere on one network
• Can communicate
• With anyone anywhere on another network
• Telecommunications as discussed in this chapter
wouldn’t be possible without interoperability
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Case 1: Best Buy, MedStar Health, and
Unifi: The Challenges and Benefits of
Wireless Mobile Applications
• Geek Squad is a 24-hour response unit that offers
computer and network support for home PC users or
businesses without an onsite IT staff.
• They use wireless Pocket PCs and other mobile devices
to access company’s business applications.
• The biggest challenge - typing on their small pocket PCs.
• Many businesses that provide or manage employees’
mobile devices for accessing company information are
developing their own software for mobile devices.
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Case Study Questions
1. What are the business advantages and limitations of the
Best Buy Geek Squad’s use of their wireless Pocket PC
mobile devices? How have they overcome the
limitations of their mobile devices?
2. What are the software development challenges of
wireless mobile devices? How are MedStar Health and
Unifi meeting those challenges?
3. Why don’t the companies in this case use some of the
thousands of software packages available for their
wireless mobile devices? What are the advantages and
limitations of this approach?
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Real World Internet Activity
1. Use the Internet to research wireless mobile
devices like the Sprint PPC-6700. Do an
analysis of the desirable features and
limitations of the smart wireless mobile device
you would most be willing to use in a work
situation. Defend your choice.
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Real World Group Activity
2. While Best Buy has standardized on the Sprint
PPC-6700 for its Geek Squad, MedStar Health
lets their medical practitioners pick their own
devices. Should companies mandate a
standard wireless mobile device for their
employees?
– Discuss the pros and cons of this question; then
formulate and defend a proposed solution.
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Case 2: Metric & Multistandard
Components Corporation
• A secure network foundation can improve a
small company’s operational efficiency, secure
sensitive data, contain costs, and enhance
employee connectivity and customer
responsiveness.
– It allows customers to securely track their orders in real
time over the Web
– It empowers customer-service agents with detailed
account information to answer their customer’s enquiry
– It can provide easy, inexpensive videoconferencing for
remote workers, vendors, and customers.
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Case Study Questions
1. What were the most important factors
contributing to MMCC’s success with its new,
secure, self-managed network? Explain the
reasons for your choices.
2. What are some of the business benefits and
challenges of self-managed and externally
managed networks?
3. Which type of network management would you
advise small-to-medium business firms to use?
Explain the reasons for your recommendation.
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Real World Internet Activity
1. Use the Internet to discover more about the
telecommunications products and services and
current business performance and prospects
of Cisco Systems and Hi-Link and some of
their many competitors in the telecom industry.
–
Which telecom hardware and software company and
IT consulting firm would you recommend to a smallto-medium business with which you are familiar?
Explain your reasons to the class.
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Real World Group Activity
2. In telecommunications network installation and
management, as in many other business
situations, the choice between “do it yourself”
and “let the experts handle it” is a crucial
business decision for many companies.
– Debate this choice for small-to-medium businesses.
See if you can agree on several key criteria that
should be considered in making this decision, and
report your conclusions to the class.
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Case 3: SAIC, Hewlett-Packard, GE,
and Others: The Business Case for
Wireless Sensor Networks
• Wireless sensor devices, or “motes,” can detect changes
in temperature, pressure, moisture, light, sound, or
magnetism and report the information using wireless
radio.
• They are a giant leap compared to traditional sensors.
• Motes cost about $100 each and are much cheaper to
install.
• The worldwide market for wireless sensors is expected to
grow from $100 million in 2005 to more than $1 billion by
2009.
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Case Study Questions
1. What are some of the business benefits
associated with using wireless networks to
collect and transmit data?
2. What are some of the challenges faced by this
use of wireless technologies? What solutions
can you offer?
3. The use of wireless networking as described in
the case is both innovative and functional.
What other business uses can you envision for
this approach?
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Real World Internet Activity
1. The companies mentioned in the case—Intel,
IBM, SAIC, and GE—are all familiar names
often associated with innovative approaches to
technology.
– Using the Internet, see if you can find examples of
other companies that have found ways in which to
apply mote wireless technology to business needs.
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Real World Group Activity
2. One way of describing this use of wireless
technologies is that it represents a marriage
between RFID (we learned about these
devices in Chapter 3) and wireless networking.
This combination of enabling technologies
results in an entirely new way of accomplishing
an old task.
– Brainstorm other combinations of existing
technologies to create new approaches to existing
business activities.
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