Transcript Computer network

Chapter 4
Telecommunications
and Networking
© Matthias Pahl/Age Fotostock America, Inc.
Chapter Outline
4.1 What Is a Computer Network?
4.2 Network Fundamentals
4.3 The Internet and the World Wide Web
4.4 Network Applications
Learning Objectives
1. Compare and contrast the two major types of
networks.
2. Describe the wireline communications media
and transmission technologies.
3. Describe the most common methods for
accessing the Internet.
4. Explain the impact that networks have had on
business and everyday life for each of the six
major categories of network applications.
Introduction
• Opening Case: Studio G
• Computers utilize telecommunications to
exchange data in order to create value,
regardless of locations and network sizes.
• Networked computers allow organizations to be
more flexible, share resources, and connect
dispersed employees and business partners.
4.1 What Is a Computer Network?
• Computer network
• A system that connects computers and other devices via
communications media so that data and information can be
transmitted among them
• Bandwidth
• Transmission capacity of a network
• Unit: bits per second (bps)
• Broadband
• Network transmission capacities
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Personal area networks (PANs)
Local area networks (LANs)
Metropolitan area networks (MANs)
Wide area networks (WANs)
The Internet
Figure 4.1 An Ethernet LAN
• Local area network: Connects two or more devices in a
limited geographical region so that every device on the
network can communicate with every other device.
Network
Interface Card
(NIC)
Figure 4.2 An Enterprise Network
4.2 Network Fundamentals
• Analog vs. digital signals
• Communications media and channels
• Network protocols
• Types of network processing
© Ilin Sergey/Age Fotostock America, Inc.
Analog versus Digital Signals
• Analog signal: Continuous waves
• Amplitude: Loudness
• Frequency: Pitch
• Digital signal: Discrete pulses
• On or off (1 or 0)
• Modem (Modulator Demodulator)
• Converts digital signals to analog and vice versa
• Types: Dial-up modem, cable modem, digital
subscriber line (DSL) modem
Communications Media and
Channels
• Transmission speed
• bps, hertz, bandwidth
• Cable
• Twisted wire
• LAN cabling: Cat5 (RJ45)
• Coaxial cable
• Fiber optics
• Broadcast
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•
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Microwave
Satellite
Radio
Infrared
TABLE 4.1 Wireline Pros & Cons
Network Protocols
• Protocol: Set of rules and procedures governing
transmission across a network
• Ethernet: A common LAN protocol
• Transmission Control Protocol/Internet Protocol
(TCP/IP)
• A file transfer protocol that can send large files of
information across sometimes unreliable networks
with assurance that the data will arrive
uncorrupted
• Uses packet switching technology
• Four layers model
Figure 4.7 The Four Layers of
The TCP/IP
Figure 4.8 Packet Switching
Data are divided into small, fixed bundles of data called packets.
Different colored packets travel by different routes to reach their
destination where they are reassembled into the complete message.
Types of Network Processing
• Distributed processing
• Divided processing works among two or more computers
• Client/server computing
• Server computers: Provide computing services
• Client computers: End users access client computers to use
services
• Fat vs. thin clients
• Peer-to-peer processing
• Each computer acts as both server and client
• Access unused CPU power among networked computers:
SETI@home
• Real-time, person-to-person collaboration: Microsoft
SharePoint
• Peer-to-peer file-sharing: BitTorrent
4.3 The Internet
and the World Wide Web
• Internet
• Began in 1969 as DoD’s project ARPAnet
• Intranet
• Supports discovery,
communication,
and collaboration
inside an organization
• Extranet
• Connects parts of the intranets of different
organizations
• Both Internet and Extranet utilize Internet Protocols
© Corbis/Age Fotostock America, Inc.
Accessing the Internet
• Connecting via an online service
• Internet service provider (ISP)
• A company that provides Internet connections for a fee
• ISPs connect to one another through network access points
(NAPs)
• Connecting via other means (Table 4.2)
Figure 4.9 Internet
(Backbone in White)
© Mark Stay/iStockphoto
Addresses on the Internet
• Internet Protocol (IP) address
• A unique address for each computer on the Internet
that distinguishes it from all other computers
• IPv4
• The most widely used format (e.g., 135.62.128.91)
• IPv6
• Can accommodate more devices (e.g., smart phones)
• The Internet Corporation for Assigned Names (ICANN)
• Coordinates IP address assignments
• Domain name system (DNS)
• Easy-to-remember names for some IP addresses
• Top-level domain (TLD) names
.com .edu .gov .org .de
.it
.ru
The Future of the Internet
• Internet2
• Developed by U.S. universities collaborating
with industry and government
• Not a separate physical network from the
Internet
• Fast, always on, everywhere,
natural, intelligent, easy,
and trusted
© Ilin Sergey/Age Fotostock America, Inc.
The World Wide Web (W3)
• Are Internet and WWW the same thing?
• The World Wide Web is a system of universally
accepted standards for storing, retrieving,
formatting, and displaying information via a
client/server architecture.
• Users access a Web site through browsers by
specifying a uniform resource locator (URL).
4.4 Network Applications
• Discovery
• Communication
• Collaboration
• E-learning and distance learning
• Virtual universities
• Telecommuting
© Matthias Pahl/Age Fotostock America, Inc.
Discovery
• Allows users to browse and search data sources, in all
topic areas, on the Web
• Search engines
• Search for specific information by key words and
report the results
• Examples: Google, Yahoo!, Bing, Baidu
• Metasearch engines
• Search several engines at once and integrate the
findings of the various search engines to answer
queries posted by users
• Example: Dogpile.com
• Use an automatic translation of Web pages to discover
materials in foreign languages
• Examples: Microsoft’s Bing translator, Google
Discovery
• Portals
• Web-based, personalized gateways to
information and knowledge that provide
relevant information from different systems
and the Internet using advanced search and
indexing techniques
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Commercial (public) portals: msn.com
Affinity portals: techweb.com
Corporate portals: Humana
Industry-wide portals: Truck.net
Mobile portals: Yahoo! Mobile
Communication
• Electronic mail (e-mail)
• The largest-volume application running on the
Internet
• Web-based call centers (customer care center)
• Services that provide effective
personalized customer contact
as an important part of
Web-based customer support
• Electronic chat rooms
• Virtual meeting place where
groups of regulars come to
chat
© Dinodia/Age Fotostock America, Inc.
Communication
• Voice communication (VoIP)
• Digitizes analog voice signals, sections them into
packets, and sends them over the Internet
• Examples: Skype, Vonage
• Unified communication (UC)
• Integrates voice, voice mail, fax, chat, e-mail, IM,
short message service, presence (location)
services, and videoconferencing
• Example: Microsoft Lync
Collaboration
• Efforts of two or more entities (individuals, teams, groups, or
organizations) who work together to accomplish certain tasks
• Work group: Two or more individuals who act together to
perform some task
• Virtual group (team): When group members are in different
locations
• Software supporting collaboration
• Microsoft Sharepoint, IBM Lotus Quickr, Google Docs, Jive
• Crowdsourcing
• Outsourcing a task to an undefined, generally large group of
people in the form of an open call
• Example: Yum!
• Teleconferencing: Conference call, video conference,
telepresence, Cisco Magic
Figure 4.15 Telepresence System
Marketwire/Newscom
E-Learning and Distance Learning
Virtual Universities
• E-learning
• Learning supported by the Web
• Distance learning (DL)
• Any learning situation in which teachers and students
do not meet face-to-face
• What are benefits and drawbacks of E-learning and DL?
• Virtual universities
• Online universities
• Students take classes from off-site locations via the
Internet
• Examples: U. of Phoenix, California Virtual Campus
Telecommuting
• Allows distributed workforce (or digital nomads)
to work from anywhere and anytime
• What are advantages and disadvantages of
telecommuting for employees?
• What are advantages and disadvantages of
telecommuting for employers?
What’s in IT for ME?
• Accounting
• Use intranets and portals to consolidate data
• Use Internet to stay up to date
• Finance
• Use intranets, Internet, and portals to access
data to support financial analysis
• Marketing
• Use intranet to coordinate sales force
• Use Internet for advertising, purchasing, and
customer service
What’s in IT for ME?
• Production/Operations Management
• Use intranet and portals to monitor inventory
and supervise productions
• Use extranet to collaborate with other firms
• Human Resources Management
• Use intranet and portals to communicate with
employees
• MIS
• Keep all organizational networks up and
running all the time
Closing Case 1: The Network
Neutrality Wars
• The Problem
• The Solution
• Questions
• How do you feel about the net neutrality issue? Do you believe
heavier bandwidth users should pay for more bandwidth? Do you
believe wireless carriers should operate under different rules than
wireline carriers? Please explain your answer.
• Evaluate your own bandwidth usage. (For example, do you upload
and download large fi les, such as movies?) If network neutrality
were to be eliminated, what would the impact be for you?
• Should businesses monitor network usage? Do you see a problem
with employees using company-purchased bandwidth for personal
use? Please explain your answer.
Closing Case 2: Marriott’s
Corporate Portal
• The Problem
• The Solution
• The Results
• Questions
• Provide examples of the advantages BrandWorks
brought to Marriott’s franchisees.
• Provide examples of how BrandWorks could be
used for functional areas of Marriott other than
marketing.