1. MANAGING INFORMATION TECHNOLOGY 7th EDITION
CHAPTER 3
TELECOMMUNICATIONS AND NETWORKING
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2. PART 1: IT BUILDING BLOCKS
Building Blocks of Information Technology
Hardware
Software
Network
Data
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3. NETWORKING AND TELECOMMUNICATIONS.
NETWORKING:
The electronic linking of geographically dispersed devices
TELECOMMUNICATIONS:
Communications at a distance, including voice and data
- Also referred to as: data communications, datacom,
teleprocessing, telecom, and networking
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4. OVERVIEW OF TELECOMMUNICATIONS AND NETWORKING
Telecommunications and networking have become increasingly important to businesses because of distributed processing and globalization
“ …networks will change everything"
Early 1990s prediction came true:
- Paul Saffo
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5. THE TELECOMMUNICATIONS INDUSTRY
Three Major Segments of Telecom Industry:
Carriers who own or lease physical plant & sell the service of communications transmission
Equipment vendors who manufacture and sell telecommunications equipment
Service providers who operate and deliver network services or provide access to or deliver services via the Internet
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6. THE TELECOMMUNICATIONS INDUSTRY
Example: AT&T
One of largest carriers in U.S. industry
In 1984, AT&T split into several companies as a result of a US Department of Justice antitrust lawsuit
Breakup of AT&T led to greater innovation through competition
But recent trend has been consolidation in the industry
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7. REASONS FOR NETWORKING
Five primary reasons for networking
Sharing of technology resources
Sharing of data
Distributed data processing and client/server systems
Enhanced communications
Marketing outreach
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8. REASONS FOR NETWORKING
1. Sharing of technology resources:
Prior to networking capabilities, computers could not even share printers….
Today, PCs share software, mainframes share storage devices, etc.
2. Sharing of data:
Enables retrieval of data stored on other nodes in the network
Allows efficient transactions between businesses, their suppliers, and their customers, based on up-to-date data
Some businesses share many terabytes of data per day
Sharing of data via Internet users
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9. REASONS FOR NETWORKING
Distributed data processing and client/server systems:
Distributed data processing
Information processing that uses multiple computers at multiple sites that are tied together through telecommunication lines
Client/server systems
A type of distributed system in which the processing power is distributed between a central server and a number of client computers
Client
Server
Transfer of Data
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10. REASONS FOR NETWORKING
4. Enhanced communications:
Telecommunication networks provide the ability to communicate through , Bulletin Boards, Blogs, Instant Messaging, Wikis, Social network sites, Videoconferencing
Links between organizations can lead to strategic alliances
SABRE airline reservation system
Electronic data interchange (EDI)
5. Marketing outreach:
Sharing data via the Internet with consumers = an important marketing and sales channel
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11. FUNCTIONS OF A TELECOMMUNICATIONS NETWORK
A telecommunications network is more than a series of wires or wireless signals…
Table 3.1
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12. ANALOG AND DIGITAL SIGNALS
Analog Signals
A signal in which some physical property continuously varies across time
Digital Signals
A signal that is not a continuous function of time, but rather a series of discrete values that represent ones and zeros
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13. ANALOG AND DIGITAL SIGNALS
Representation of digital and analog signals
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14. ANALOG AND DIGITAL SIGNALS
Digital computer data does not naturally mesh with analog transmission; it must be converted from ones and zeros to analog signals
Solutions:
Modem (Modulator/Demodulator)
Digital networks
Advantages of lower error rates and higher speeds
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15. TYPES OF TRANSMISSION LINES
Private (dedicated physical lines)
Advantage:
- Ensures quality of transmission
Disadvantage:
Costly
Switched (such as public telephone network)
- Less costly
Disadvantages:
- Message may take many different routes
- Quality of transmission may degrade
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16. TYPES OF TRANSMISSION LINES
Simplex
Data can only travel in one direction
Half Duplex
Data can travel in both directions, but not simultaneously
Full Duplex
Data can travel in both directions at once
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17. TRANSMISSION MEDIA Twisted Pair
Literally, wires that are twisted to reduce interference
Can be shielded (STP) or unshielded (UTP), but the most commonly used is UTP
Medium used for public telephone networks
Transmission speeds vary greatly
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18. TRANSMISSION MEDIA Coaxial (Coax) Cable Baseband
- Inexpensive, designed for digital transmission
Broadband
- Originally for analog, now used for digital
- Commonly used in television cable
Figure 3.2
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19. Wireless TRANSMISSION MEDIA
Not truly a transmission medium, but rather a broadcast technology in which radio signals are sent through the air
Cordless telephones and cellular telephones now widely used
Wireless technologies:
Wireless LANs
Microwave
Line of sight
Satellite
Long distances
RFID
Bluetooth
Wireless Cards
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20. TRANSMISSION MEDIA Wireless Wireless LANs - Growing in popularity
- Useful when wiring is not possible
- Slower than some wired solutions
- Allow mobile devices to connect to network
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21. TRANSMISSION MEDIA Wireless Microwave
- Widespread use for several decades
- Line of sight transmission
- Limited to mile distances because of curvature of the earth
- Expensive, but less costly than fiber optic cables
Microwave Tower
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22. TRANSMISSION MEDIA Wireless Satellite Geostationary Earth Orbit (GEO)
- Remains stationary relative to earth
Low Earth Orbit ( LEO)
- 400 to 1000 miles above earth
Figure 3.3
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23. - First major LEO project with 66 satellites
TRANSMISSION MEDIA
LEO projects beginning in 1990s
Iridium
- First major LEO project with 66 satellites
- Faced high operating costs which resulted in bankruptcy
Mostly military subscribers
Globalstar
- LEO project with 40 satellites that does not provide global coverage
Teledesic
- Ambitious project with original plans to launch 840 satellites
- This was later cut to 288 satellites, then 30, and then the program was cancelled
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24. Wal-Mart gets tough with suppliers about RFID
TRANSMISSION MEDIA
Wireless
RFID
- Acronym for Radio Frequency Identification
- An old technology that became popular in business after Wal-Mart required the use of RFID by some of its suppliers to improve inventory and supply chain management
Wal-Mart and RFID
Wal-Mart CIO on RFID
Wal-Mart gets tough with suppliers about RFID
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25. TRANSMISSION MEDIA Wireless RFID Two Broad Types of RFID tags:
- Active – these tags have their own power supply and can transmit messages continuously, on request, or on a schedule
Cost over $1.00
- Passive – these tags only send a response to an incoming radio signal
Cost in the $ $0.20 range
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26. TRANSMISSION MEDIA Wireless Bluetooth
Named after Danish King who united Denmark
Short-range radio technology
Designed to consume very little electrical power and be produced at a low cost
Found in a growing number of devices such as cell phones, laptops, headsets, keyboards, mice, and home appliances
- Thousands of Bluetooth products in use today
Bluetooth Devices
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27. TRANSMISSION MEDIA Fiber Optics
Light pulses through a thin fiber of glass or silica
Faster and more reliable than other media
Large diameter fiber is multimode (multiple light rays at the same time) while smaller diameter is single mode
But smaller diameter fiber has larger capacity due to light rays bouncing less….
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28. NETWORK ACCESS FOR INDIVIDUALS
Internet Service Providers (ISPs) sell access to the Internet
Consumers now have more options including faster broadband connections
- Digital Subscriber Line (DSL) is a connection through a telephone company
- Cable modem is a connection through a cable television company
- Satellite
With one-way service, individuals must obtain uplink service from another provider
Other Wireless access may be through a municipal carrier or a private company
Pricing methods for personal Internet access
- Fixed price (usually monthly plans)
But hotels, airports, cafes, etc. now offer Internet access for short periods of time
- Cost based on usage (data transferred)
- Also offered “free” to customers in various locations
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29. NETWORK TOPOLOGY
Network topology = configuration or arrangement of the devices
Bus
- All devices are attached to one cable
- Single-point failure
Ring
- Similar to bus, but ends are attached
- Not susceptible to single-point failure
Star
- All nodes are attached to central device
- Susceptible to failure of central device, but easy to identify cable failure
Tree
- Similar to the star, but with a hierarchical structure
Mesh
- Devices link to multiple other devices
- A failure has little impact on the network, but costly
Figure 3.4
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30. NETWORK TYPES Six types: Computer Telecommunications Networks
Local Area Networks (LANs)
Backbone Networks
Wide Area Networks (WANs)
The Internet
Internet2
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31. NETWORK TYPES Computer Telecommunications Networks:
This was the only type of network until the 1980s
Commonly used in mainframe architectures
Figure 3.5
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32. NETWORK TYPES Local Area Networks (LANs)
Standards developed by the Institute for Electrical and Electronic Engineering (IEEE)
IEEE 802 is a family of standards for LANs and metropolitan area networks
- Five types of LANs in common use today – 3 wired, 2 wireless
Contention Bus (IEEE 802.3)
Token Bus (IEEE 802.4)
Token Ring (IEEE 802.5)
Wi-Fi (IEEE )
WiMAX (IEEE e)
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33. NETWORK TYPES - LAN Contention Bus (IEEE 802.3) - Developed by Xerox
- Usually called Ethernet after the original Xerox version
- Half-duplex
- All devices must contend to use
CSMA/CD protocol for collisions
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34. NETWORK TYPES - LAN Token Bus (IEEE 802.4) Token Ring (IEEE 802.5)
- A token (special message) is passed among devices
- Only the device with the token can transmit a message
Important for Manufacturing Automation Protocol (MAP)
Token Ring (IEEE 802.5)
- Developed by IBM
Combination of ring topology with use of tokens (used the same way as in token bus)
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35. NETWORK TYPES - LAN Wi-Fi (IEEE 802.11) - Short for Wireless Fidelity
Most common wireless LAN type today
- Uses a shared Ethernet design
- CSMA/CA Protocol
Similar to CSMA/CD, but with less collisions
- Commonly used in offices to supplement wired Ethernet networks and support mobile devices, or in areas where adding hardwiring is problematic
- Many U.S. cities are offering Wi-Fi networks
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36. NETWORK TYPES WiMAX (802.16e) - Newest of the network types
Similar to Wi-Fi, but operates over longer distances and at higher speeds
- Can use both licensed and non-licensed frequencies
Clearwire = leading vendor at this time
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37. NETWORK TYPES
Wireless Local Area Networks: Some Implementation Problems - More difficult to secure than other network types - Organizations that offer wireless access to entice customers have problems with non-customers or unprofitable customers overusing the network - Unauthorized wireless use is also problematic in condos and apartments
Multiple Unsecured Wireless Networks
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38. NETWORK TYPES 3. Backbone Networks Connect LANs Key to internetworking
Figure 3.8
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39. BACKBONE NETWORK DEVICES
Hardware devices for backbone (middle-distance) networks
Hub: Simple device that forwards all messages to every device attached to it
Wireless Access Point: Central device that connects wireless LAN to other networks
Bridge: Connects two LAN segments and only forwards messages that need to go to other segment
Switch: A multiport bridge; connects two or more LAN segments
Router: Connects two ore more LANs and only forwards messages that go to the other LAN
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40. NETWORK TYPES 4. Wide Area Networks (WANs)
Similar to LANs, but cover greater distances (“long-haul”)
We will consider the following three general types of WANs because they each have advantages and disadvantages:
- Switched Circuit
Dedicated Lines
Packet-switched
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41. NETWORK TYPES - WAN Switched Circuit (or circuit-switched):
A single physical path is temporarily created between two nodes for their exclusive communication
Most widely available means of implementing a WAN using a switched circuit connection is to use the ordinary telephone network
Advantages
- Easy to set up
Disadvantages
- Low speed
- High error rates
There are two different pricing schemes available for this service
- Direct Distance Dialing (DDD) - pay for usage
- Wide Area Telephone Service (WATS) - fixed rate
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42. NETWORK TYPES - WAN Dedicated Lines:
These are permanent channels exclusive to the business
Advantages
- High capacity
- Low error rates
Disadvantages
Expensive
Two different types of dedicated circuits:
- Leased lines are cable, microwave, or fiber connections
- Satellite circuits are popular for organizations with many global locations
- SONET lines are high-capacity leased fiber lines
Table 3.3
Wide Area Networks
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43. NETWORK TYPES - WAN Packet-switched: Advantages
Multiple connections exist simultaneously over the same physical circuit
Messages are broken up into packets
Businesses use PADs (Packet assembly/disassembly devices) to connect their networks to a common carrier network
Advantages
- Efficient use of network
- Can be high capacity
Disadvantages
- Packets may arrive in different order or with delay
Figure 3.9
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44. NETWORK TYPES 5. The Internet
Network of networks that use the TCP/IP protocol
Similar to an enormous WAN
733 million hosts as of January 2010
Began with ARPANET and NSFNET
ARPANET (Advanced Research Projects Agency Network) was created by the US Department of Defense
NSFNET (National Science Foundation Network) was created to link supercomputers for research
Each of these were largescale, packet-switching networks that led to the creation of the Internet
ARPANET
NSFNET
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45. NETWORK TYPES Internet Applications
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46. NETWORK TYPES 6. Internet2
Not-for-profit consortium made up of over 200 universities, as well as industry and government partners, to develop and deploy advanced network applications and technologies for research and commercial purposes
Goals
Create a leading-edge network capability for the national research community
Enable revolutionary Internet applications based on a much higher-performance Internet than we have today
Ensure the rapid transfer of new network services and applications to the broader Internet community
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47. NETWORKING PROTOCOLS Network Protocols
An agreed-upon set of rules or conventions governing communication among elements of a network
Open Systems Interconnection (OSI) Reference Model
Skeleton for standards developed by International Organization for Standardization (ISO)
Conceptual framework to understand how communications in networks take place
Figure 3.11
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48. NETWORKING PROTOCOLS
Transmission Control Protocol/Internet Protocol (TCP/IP)
Created to link different types of networks (e.g., satellite and ground packet networks) together into a network of networks
Has become de facto standard protocol for networking
-TCP is responsible for the reliable and ordered transmission of messages
- IP is responsible for routing individual packets based on their individual addresses (IP addresses)
Roughly corresponds to network and transport layers of OSI model
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49. NETWORKNG HAS BECOME CRITICAL TO DO BUSINESS
Networking and Telecommunications have become necessary for businesses to function
Increasing access to the Internet in developing countries due to new lines being funded by private and public organizations
Impact of cut Internet cables in Middle East
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Publishing as Prentice Hall
Copyright © 2011 Pearson Education, Inc. publishing as Prentice Hall