Copyright © 2011 Pearson Education, Inc. publishing as Prentice Hall 3-1 MANAGING INFORMATION...

Copyright © 2011 Pearson Education, Inc. publishing as Prentice Hall 3-1

MANAGING INFORMATION TECHNOLOGY7th EDITION

CHAPTER 3

TELECOMMUNICATIONS AND NETWORKING


PART 1: IT BUILDING BLOCKS

Building Blocks of Information Technology

Hardware Software Network Data


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


OVERVIEW OF TELECOMMUNICATIONS AND NETWORKING

• Telecommunications and networking have become increasingly important to businesses because of distributed processing and globalization

Early 1990s prediction came true:

“ …networks will change everything" - Paul Saffo


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


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


REASONS FOR NETWORKING

Five primary reasons for networking

1. Sharing of technology resources

2. Sharing of data

3. Distributed data processing and client/server systems

4. Enhanced communications

5. Marketing outreach



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



3. 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 ServerTransfer of Data



4. Enhanced communications:• Telecommunication networks provide the ability to communicate

through Email, Bulletin Boards, Blogs, Instant Messaging, Wikis, Social network sites, Videoconferencing

• Links between organizations can lead to strategic allianceso SABRE airline reservation systemo Electronic data interchange (EDI)

5. Marketing outreach:• Sharing data via the Internet with consumers = an important

marketing and sales channel


FUNCTIONS OF A TELECOMMUNICATIONS NETWORK

• A telecommunications network is more than a series of wires or wireless signals…

Table 3.1


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



• Representation of digital and analog 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


TYPES OF TRANSMISSION LINES

Private (dedicated physical lines)• Advantage:

- Ensures quality of transmission• Disadvantage:

- Costly

Switched (such as public telephone network)• Advantage:

- Less costly• Disadvantages:

- Message may take many different routes

- Quality of transmission may degrade


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


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


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


TRANSMISSION MEDIA

Wireless• 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– Line of sight

• RFID• Bluetooth

Wireless Cards

http://static.howstuffworks.com/gif/wireless-network-new-5.jpg


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


TRANSMISSION MEDIA

Wireless

• Microwave

- Widespread use for several decades

- Line of sight transmission

- Limited to 25-50 mile distances because of curvature of the earth

- Expensive, but less costly than fiber optic cables

Microwave Tower

http://www.freefoto.com/images/04/23/04_23_93---Microwave-Communication-Tower_web.jpg


TRANSMISSION MEDIA

Wireless

• Satellite

1. Geostationary Earth Orbit (GEO)

- Remains stationary relative to earth

2. Low Earth Orbit ( LEO)

- 400 to 1000 miles above earth

Figure 3.3


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


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 RFIDWal-Mart CIO on RFID

Wal-Mart gets tough with suppliers about RFID

http://www.computerworld.com/s/article/82155/Wal_Mart_Backs_RFID_Technology?taxonomyId=121

http://www.businessweek.com/technology/content/feb2004/tc2004024_3168_tc165.htm

http://www.informationweek.com/news/mobility/RFID/showArticle.jhtml?articleID=205900561


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 $0.08 - $0.20 range


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

http://www.macos.utah.edu/documentation/hardware/bluetooth/mainColumnParagraphs/01/image/bluetooth_connections.png


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….


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


NETWORK TOPOLOGY

Network topology = configuration or arrangement of the devices

Figure 3.4

• 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


NETWORK TYPES

Six types:

1. Computer Telecommunications Networks

2. Local Area Networks (LANs)

3. Backbone Networks

4. Wide Area Networks (WANs)

5. The Internet

6. Internet2


NETWORK TYPES

1. Computer Telecommunications Networks:

• This was the only type of network until the 1980s• Commonly used in mainframe architectures

Figure 3.5


NETWORK TYPES

2. 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 wirelesso Contention Bus (IEEE 802.3)o Token Bus (IEEE 802.4)o Token Ring (IEEE 802.5)

o Wi-Fi (IEEE 802.11)o WiMAX (IEEE 802.16e)


NETWORK TYPES - LAN

o 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


NETWORK TYPES - LAN

o Token Bus (IEEE 802.4)- A token (special message) is passed among devices

- Only the device with the token can transmit a message- Important for Manufacturing Automation Protocol (MAP)

o Token Ring (IEEE 802.5)- Developed by IBM- Combination of ring topology with use of tokens (used the

same way as in token bus)


NETWORK TYPES - LAN

o 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


NETWORK TYPES

o 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


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

http://images.pcworld.com/howto/graphics/127616-networkOptions_b.jpg


NETWORK TYPES

3. Backbone Networks

• Connect LANs• Key to internetworking

Figure 3.8


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


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


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


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

http://www.edrawsoft.com/images/network/Campus%20Network%20Overview_Full.png


Packet-switched: • 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

Figure 3.9

• Advantages- Efficient use of network- Can be high capacity

• Disadvantages- Packets may arrive in different order or with delay

NETWORK TYPES - WAN


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 ARPANETNSFNET

http://www.mundi.net/maps/maps_001/arpanet.gif

http://www.computerhistory.org/internet_history/full_size_images/1988_nsfnet_map.gif


NETWORK TYPES

Internet Applications


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


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


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


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 - 2008

http://www.infoworld.com/t/networking/cut-cable-disrupts-internet-in-middle-east-995




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Copyright © 2012 Pearson Education, Inc. Publishing as Prentice Hall

Copyright © 2011 Pearson Education, Inc. publishing as Prentice Hall 3-1 MANAGING INFORMATION...

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