Transcript Chapter 5
Telecommunications, Networks, and the Internet Chapter Eight (9
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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
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
1 billion instant messages per day
4 billion e-mails each day
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 5
The Business Telecommunications Environment
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
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?
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
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
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)
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
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
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.
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
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
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
Electromagnetic signals can be described in terms of a stream of photons each traveling in a wave like 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, X rays, 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 LF MF HF 100 1K 100K
All waves behave similarly Frequency differences
Amount of data Distance Interference / Noise
1M 1M 10M VHF UHF 100M Microwave Optical 1G 10G Hertz 24
Transmission Speeds
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*(log 2 )*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
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
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
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
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
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
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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