Information Systems: Creating Business Value by Mark Huber, Craig Piercy, and Patrick McKeown

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Information Systems Creating Business Valueby
Mark Huber, Craig Piercy, and Patrick McKeown

• Field Guide C The Details of Networking

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What We Will Cover

• Network Architecture
• Network Layer Model
• Local Area Networks
• The Internet A Network of Networks
• The World Wide Web

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Student ROI (Return on Investment)

• Your investment of time and effort in this course
  will result in your being able to answer these
  questions
• What is the client/server architecture, and how
  does it work?
• How does the network layer model describe a wide
  area network?
• How are local area networks configured?
• How does the Internet work?
• What makes the World Wide Web valuable to
  knowledge workers?

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Client/Server Computing

• The most common network architecture is the
  client/server architecture.1

1R. T. Watson, Organizational Memory, 5th ed.
(New York John Wiley, 2006, p. 360
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Client/Server

• Processing is shared among multiple small
  computers known as clients that are connected via
  a network to a host computer known as a server.
• Clients - typically PCs, a type of high-powered
  small computer built for specialized applications
  called a workstation, or a network computer.
• Server - typically dedicated to a specific type
  of processing, such as providing files with a
  file server, responding to database queries with
  a database server, or handling high-speed
  processing with an application server.
• Because both the client and the server are
  capable of processing, processing is shared
  between the two computers depending on the
  capability of each.

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Three-Tiered Architecture
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Types of Servers
Server Type Purpose
File Provides both software and data files to users
Database Handles queries to a large database and returns matching records
Application Handles high speed processing
Web Handles requests for Web pages
Mail Sends and receives e-mail for entire organization
Fax Sends and receives faxes for entire organization
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Servers on a Network
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Client/Server Advantages and Disadvantages
Advantages Disadvantages
Computing burden can be shared among servers and clients Programming relationship between clients and servers is more complex
Servers can be specialized to one particular type of task System upgrades require that all clients and servers be upgraded regardless of location
Upgrading system can be done in small steps
Loss of client does not stop other clients from accessing server
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Peer-to-Peer Networks

• It is possible to set up a peer-to-peer network,
  where each computer in the network is on the same
  level as other computers, and each computer is
  equally responsible for overseeing the functions
  of the network.
• Any two computers in a peer-to-peer network may
  communicate directly with one another, or they
  may communicate through intermediate peer
  computers.
• Peer-to-peer networks may be easier to setup, but
  are not as efficient as client/server networks.

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Comparing Client/Server and Peer-to-Peer Networks
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3 Software Layers on the Computer

• Computer
• Operating System / Environment
• Applications
• You

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Black Boxes and Layers
3-Layer Model
4-Layer Model
Applications
Applications
Operating System/Environment
Redirector
OS
NetworkOS
Hardware
LocalH/W
NetworkH/W
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Network Layer Model
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Network Standard OSI Architecture
SevenOSI Layers
Application Layer User software (e.g.
spreadsheet).
Presentation Layer Operating system
functionality.
Session Layer Connection between user network
(e.g. logins).
Transport Layer Find best path for transmission.
Network Layer Routing (to which host, etc.)
Data Link Layer Error checking (parity, etc).
Physical Layer Packets on the media (T/P, Fiber,
etc).
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The Internets TCP/IP Standard
Application Layer
Application or Process Layer
Presentation Layer
Session Layer
OSI Model
Host-to-Host Transport Layer
Transport Layer
Network Layer
Internet Protocol (IP)
Data Link Layer
Network Interface
Physical Layer
Physical Layer
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Application Software Layer

• Application software is the software on each
  computer on the network that the user sees and
  uses to send and receive messages and data
  between computers.
• Web browsers, e- mail, etc.
• Application layer protocols simple mail transfer
  protocol (SMTP) for e-mail, hypertext transfer
  protocol (HTTP), Electronic data interchange
  (EDI)
• The message may also be encrypted.

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Network Connection Layer

• The message from the application software layer
  is formatted according to whatever protocol will
  actually be used to send it over the network.
• Commonly used protocols
• Transmission Control Protocol/Internet Protocol
  (TCP/IP).
• Ansi X 12 or EDIFACT for EDI.

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Converting Data into Packets

• IP Address a unique identifier given to each
  device directly connected to the network.
• Consists of four groups of numbers in the range 0
  to 255 separated by periods or decimal points.
• The message is divided into smaller digital units
  called packets, each of which contains a specific
  number of bytes.

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Packet Switching

• The physical layer sends packets over telephone
  lines, or other media, using packet switching.
• Packet switching - individual packets are routed
  through the network based on the destination
  address contained in each packet. With packet
  switching, the same data path can be shared among
  many computers in the network, and if a computer
  on the network is inoperable, the packet finds
  another way to reach its destination.
• A router is a special type of computer that has
  the sole purpose of accepting packets and
  determining the best way to send them to the
  destination computer--that is, the router
  specializes in switching the packets.
• The sequence order allows the receiving computer
  to reconstruct the message.

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Sending Data Between Computers on the Internet
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Data Components Layer

• Twisted pair - consists of twisted pairs of
  copper wires and is similar to the wiring used in
  much of the existing telephone system.
• Coaxial cable - used to transmit cable television
  signals into your home. It is also widely used in
  networks.
• Fiber optic cable - consists of hundreds of glass
  fiber strands that can transmit a large number of
  signals at extremely high rates of speed.
• Microwaves - high-frequency radio transmissions
  that can be sent between two stations
• Wireless several technologies that allow data
  to be transmitted without wires

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Copper Wire Compared to Fiber Optics
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Data Component Media2
Media Cost Error Rates Speed
Twisted Pair Low Low Low-high
Coaxial Cable Moderate Low Low-high
Fiber Optics High Very Low High - very High
Radio Low Moderate Low
Infrared Low Moderate Low
Microwave Moderate Low- Moderate Moderate
Satellite Moderate Low- Moderate Moderate
2Source Jerry Fitzgerald and Alan Dennis,
Business Data Communications and Networking, 8th
ed., p. 85, New York John Wiley, 2005.
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Data Rate and Bandwidth Issues

• The data rate is measured in bits per second
  (bps).
• A digital subscriber line (DSL) transmits
  computer data in a digital form along the same
  telephone line that is used for analog voice
  communications.
• T-carrier circuits are dedicated digital lines
  that are leased from a telecommunications company
  to carry data between specific points.
• The term bandwidth is often used in relationship
  to data rate and is a measure of how fast data
  flows on a transmission path.
• Baseband - only a single digital signal is
  carried through the media.
• Broadband - variety of different analog signals
  are being transmitted.

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Baseband Compared to Broadband
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Maximum Data Rates
Transmission Method Maximum Data Rate Comments
Standard telephone service 56 Kbps Available everywhere
Digital Subscriber line (DSL) 6 Mbps in 640 Kbps out Becoming more available. Does not slow down as more people sign up.
Cable As high as 55 Mbps but averages between 200 Kbps and 2 Mbps Cable must support two-way communication available in many locations but slows down as more people use it in a specific location
T-1 to T-4 1.544 Mbps - 274 Mbps Leased lines used for commercial telecommunication
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Local Area Networks

• Local Area Networks (LAN) a network connected
  over a small geographic area. LANs are popular
  for
• Sharing information
• Sharing resources
• Sharing software
• Sharing hardware
• Most LANs are client/server networks
• LANs can also be implemented through peer-to-peer
  networks

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LAN Terminology

• Ethernet protocol technology standards for
  connecting computers into a LAN.
• A bus network uses a a main cable, called a bus,
  to connect all clients and servers on the
  network.
• A gateway is the combination of hardware and
  software that connects two dissimilar computer
  networks.
• A bridge connects two similar networks.

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Wireless LANs

• Wireless LANs (WLANs) replaces cabling with
  wireless transmissions that use radio frequencies
  to transmit information between individual
  computers
• The individual computers do not communicate
  directly with each other instead they
  communicate with a wireless network hub or
  router, which is also used to bridge the wireless
  network to traditional ethernet or provide a
  shared Internet connection.
• Wi-Fi (for Wireless Fidelity) also called IEEE
  802.11b standard, the current popular standard
  for wireless networking supports data rate of 11
  megabits/second, with a typical range through
  open air of about 220-1100 yards (200-1000
  meters).

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Laptops Connected to a Wireless LAN
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Bluetooth and PANs

• Personal Area Network (PAN) - a technology that
  enables wireless devices such as mobile
  telephones, computers, and PDAs to communicate
  over a short distanceless than 33 feet (10
  meters).
• Bluetooth - embeds a low-cost transceiver chip in
  each device, making it possible for wireless
  devices to be totally synchronized without the
  user having to initiate any operation.
• The overall goal of Bluetooth might be stated as
  enabling pervasive connectivity between personal
  technology devices without the use of cabling.

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The Internet Network of Networks

• Originally developed in the 1960s and 1970s as a
  way of sharing information and resources among
  universities and research institutions, the
  Internet began its dramatic growth in 1991.
• Today, the Internet is growing so fast that no
  one can say exactly how many people are using it,
  with estimates ranging as high as over 1.10
  billion in 2005.
• A primary reason for the explosive growth of the
  Internet is the tremendous amount of data,
  information, and resources that people can access.

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What is the Internet?

• The Internet is a network of networks.
• To connect to the Internet, your computer will
  usually first connect to a LAN through a network
  interface card (NIC) or to an ISP through a modem
  and telephone line.
• The LAN, mainframe, or ISP is, in turn, connected
  to a regional network via a high-speed (T-1)
  telephone line. The regional network in turn
  links into the backbone of the Internet.
• With each network, there is at least one host
  computer that is connected to the Internet with
  full two-way access to other computers on the
  Internet and with a unique Internet address.
• Each host computer that connects to the Internet
  uses the TCP/IP protocol for assigning addresses
  and uses packet switching for exchanging
  information.

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Connecting to the Internet
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Addresses

• An e-mail address is composed of two parts the
  user name and the server address.
• The user name is assigned to a person or
  organization that is connected to a server, and
  it is separated from the server address by the at
  symbol (_at_).
• Server address (a.k.a. domain name) the IP
  address of the email host. The right-most part of
  the address is known as the top level domain.
• Server addresses are easy-to-remember versions of
  the numeric IP addresses.

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Top Level Domains
Type of Organization Designation Example
Commercial company .com www.ebay.com (eBay Auctions)
Educational institution .edu www.uga.edu (The University of Georgia)
Nonprofit organization .org www.redcross.org (The Red Cross)
Network provider .net www.netscape.net (Netscape)
Government .gov www.ustreas.gov (U.S. Treasury Department)
Military .mil www.usmc.mil (The U.S. Marine Corps)
Aerospace organizations .aero www.ba.aero (British Airways)
Businesses .biz www.webmaster-resource.biz (Webmaster-Resource.biz, an e-commerce company)
Cooperatives .coop www.credit-cooperatif.coop (Crédit Coopératif Group in France)
Various .info www.lanka.info (Information on Sri Lanka)
Museums .museum mhp.moscow.museum (Moscow House of Photography in Russia)
Various .name www.yourname.name
Professionals .pro www.broadway.pro (Broadway theater shows)
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Internet Operations
Internet Operations Purpose
E-mail Asynchronously exchange electronic messages with other Internet users
FTP Download files (software, documents, or data) from or upload files to a server located on the Internet
Newsgroups Participate in a wide variety of online discussion groups
Telnet Work on a computer elsewhere on the Internet
Internet Relay Chat Synchronously exchange electronic messages with other Internet users
World Wide Web Transfer text, images, video, and sound to your computer search for information on Internet
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The World Wide Web

• The Web is a body of software and a set of
  protocols and conventions based on hypertext and
  multimedia that make the Internet easy to use and
  browse.
• Hypertext is a method of linking related
  information in which there is no hierarchy or
  menu system.
• Multimedia is an interactive combination of text,
  graphics, animation, images, audio, and video
  displayed by and under the control of a computer.

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Using a Browser

• The Web is a special type of client/server
  network. To access the Web, the client computer
  uses software called a browser that initiates
  activity by sending a request to a Web server for
  certain information. The Web server responds by
  retrieving the information from its disk and then
  transmitting it to the client.
• Browser application layer software used for
  sending requests and displaying the results
• Hypertext markup language (HTML) - tags in World
  Wide Web documents that are part of a special
  publishing language
• Documents on the Web are referred to as Web
  pages, and their location is a Web site.

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A Web Page and Source Code
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Web Pages vs. Physical Pages
Characteristics Web Page Physical Page
Form Electronic Ink on paper
Amount of information Can extend beyond single screen Restricted to single piece of paper
Types of information Can include text, images, audio, and video information Restricted to text and images
Links to other pages Can be linked to other pages through hypertext Can be linked only through a separate index
Creation Can be created with HTML and saved to a server Can be created using word processor and printer
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Web Technology

• IP Address
• Four numbers that identify a node on the Internet
• e.g. 72.21.206.5 (a.k.a. www.amazon.com)
• Hypertext Transfer Protocol (HTTP)
• Communication protocol used to transfer pages
  from Web server to browser
• HTTPS is a more secure version
• Uniform Resource Locator (URL)
• Mnemonic Web address corresponding with IP
  address
• Also includes folder location and html file name

CommunicationProtocol
FolderPath
Web Page HTML File
Domain Name
http//www.amazon.com/gp/homepage.html
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Internet Protocols
Protocol Purpose
http Retrieve Web pages
file Retrieve files from local hard disk
telnet Log on to a remote computer connected to the Internet
ftp Download or upload files from an Internet FTP server
mailto Send outgoing e-mail
news Display news group
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Wireless Networks

• The fastest growing trend in networks is wireless
  networks, both WANs and LANs.
• Primary advantage devices connected to the
  network can go virtually anywhere
• In the case of wireless WANs, a mobile telephone
  client is the most popular method of connecting
  to the Internet and Web.
• A number of mobile telephone companies have
  collaborated to create a special protocol, called
  Wireless Application Protocol (WAP), just so
  their telephones can connect to the Internet.
• Short Message Service (SMS ) is a service for
  sending text messages up to 160 characters long
  to mobile telephones.
• Global System for Mobile communication (GSM)
  protocol is the most widely used standard mobile
  telephone protocol in the world, with the
  exception of the United States where it is
  gaining ground.

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How we make phone calls

• Changing due to VOIP
• Voice over Internet Protocol
• Vonage, Time-Warner (and others)
• How you call
• ATA
• analog/digital converter to translate your voice
  into digital for transmission over the Internet.
• IP-Phones
• Have the circuitry necessary to do the A/D
  conversion onboard.
• Your Computer
• Any multi-media computer with a network
  connection and the necessary software (actually
  one can get the software for free at
  http//www.skype.com/).

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Advantages Issues

• For the user, flexibility one can take their
  softphone, or ATA, or software on a laptop
  anywhere theres a network connection
• For businesses, it should be cheaper (should be
  for individuals too)
• For the available bandwidth, a more efficient way
  to allocate space to phone calls (see arguments
  about circuit versus packet switching)
• See http//computer.howstuffworks.com/ip-telephony
  .htm for more details
• FCC doesnt have clear rules yet for example,
  current traditional telecoms pay for stuff like
  911 and associated services.
• How will pricing eventually pan out?