Download - © McGraw-Hill Companies, Inc., McGraw-Hill/Irwin Extended Learning Module E Network Basics
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STUDENT LEARNING OUTCOMES
1. Identify and describe the four basic concepts on which networks are built and describe what is needed to set up a small peer-to-peer network at home.
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STUDENT LEARNING OUTCOMES
3. Describe the components used to build large business networks and define and compare local area networks (LANs), wide area networks (WANs), and metropolitan area networks (MANs).
4. Compare and contrast the various Internet connection possibilities.
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STUDENT LEARNING OUTCOMES
5. Compare and contrast the types of communications media.
6. State the four principles of computer security and describe how different network security devices reflect those principles.
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INTRODUCTION
Computer network – two or more computers connected so that they can communicate with each other and share information, software, peripheral devices, and/or processing power
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Basic Principles of Networks
Four main principles1. Each computer must have a
network interface to provide a doorway for information
2. The network usually has at least one connecting device
3. The network must have communications media to transport information
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Basic Principles of Networks
4. Each computer must have software to move information in and out of the computer
These four principles apply to all networks, large and small
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HOME NETWORKS
A typical home network setup has
1. An Ethernet network card in each computer or a wireless card in each laptop
2. Network cables to transmit signals, or radio waves for wireless
3. A DSL or cable modem connection and a broadband/home router
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Network Cards
Network interface card (NIC) – an expansion card or PC card that connects your computer to a network Ethernet card – the most
common type of network interface card
Built into the motherboards of many new computers
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Wired Transmission Media
Cat 5 (Category 5) cable – better-constructed version of phone twisted-pair cable
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Wireless Transmission Media
Wireless Access Point (WAP) – device that allows a computer to use radio waves to access a network
Connects to switch with a cable like a wired computer
May be built into broadband router and not require separate cabling
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Home Internet Service
Broadband router or home router – a device to connect computers together to share DSL or cable Internet service in a home or small office One port to plug into DSL or cable connection to
connect to the Internet Usually several ports to build a network for home
computers or printers and share Internet connection
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Network Software
Makes each computer's hardware work Can use Windows Turn on filesharing to make files available
to other computers on the network
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NETWORK COMPONENTS
Switch – a device that connects computers and repeats transmissions only to intended recipient Multiple conversations can occur
simultaneously between different sets of computers
Only recipient computer sees each message
Computers can still broadcast messages to all other computers on the network
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NETWORK COMPONENTS
Router – a device that connects subnetworks (subnets) of a larger network Can connect different buildings at
same or different locations Passes transmissions from one
network to another May pass through multiple routers on
the way from source to destination
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NETWORK COMPONENTS
More on routers Home/broadband routers often
have built-in switches Corporate routers generally require
separate switches Routers must be configured with
information about the networks they connect
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NETWORKS BY DISTANCE
Large networks can be classified by the size of the area(s) they serve: Local Area Network (LAN) –
network that serves a building or buildings in a contiguous area
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NETWORKS BY DISTANCE
More networks by distance Wide Area Network (WAN) – a
set of connected networks serving areas not immediately contiguous
Metropolitan Area Network (MAN) – a set of connected networks within the same city or metropolitan area but not in immediate proximity to each other
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THE INTERNET
A vast network of computers that connects people all over the world
Computers pass messages through routers to their ultimate destinations
Each router determines whether it has a direct path to the recipient or whether to send the message on to another router
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Bandwidth
The amount of information that can be transferred in a given amount of time
Usually expressed as bits per second (bps) Higher bandwidths expressed as
kilobits per second (Kbps) – thousands of bits per second
megabits per second (Mbps) – millions of bits per second
gigabits per second (Gbps) – billions of bits per second
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Internet Connection Types
Phone line and dialup modem Phone line and DSL modem Cable TV line and cable modem Satellite modem Dedicated high-speed business
lines
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Broadband Internet Connection
Broadband – high-capacity telecommunications line capable of providing high-speed Internet service
All Internet access methods on the previous slide are broadband except the dialup modem
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Dialup Connection
Modem – connects a computer to a phone line to access another computer or network
Modulates outgoing signal from digital to analog form
Demodulates incoming signal from analog to digital form
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Digital Subscriber Line (DSL)
Digital Subscriber Line (DSL) – high-speed Internet connection using phone lines, which allows you to use your phone for voice communications at the same time
Runs at a higher frequency than voice conversations, so not supported on some older phone lines
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Cable Modem
Cable modem – uses your TV cable to deliver an Internet connection
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Satellite Modem
Satellite modem – delivers Internet access by means of a satellite dish
Satellite TV and modem may share same dish or may be separate
Connects to computer or broadband router like cable modem
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T1 and DS3 Business Lines
T1 and DS3 developed by phone companies to carry many long-distance voice conversations
T1 runs up to about 1.5 Mbps DS3 runs up to about 45 Mbps Can carry both voice and
network over the same lines
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Frame Relay and ATM Business Services
Frame Relay and ATM are used to connect many branch offices to the main office
Use virtual circuits to simulate having a line from every office to every other office
Virtual CircuitsVirtual Circuits
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Comparison of Connection Types
Telephone modem + Inexpensive and available anywhere
there's a phone line - Slow, and ties up the line for voice calls
too DSL
+ Higher-speed connection, doesn't tie up the phone line for voice calls, and can be left on all the time
- Not available in all areas or on all lines
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Comparison of Connection Types
Cable modem + Higher-speed connection, doesn't use
the phone line at all, and is always-on - Connection shared with others in the
neighborhood, so speed may vary Satellite modem
+ Available in remote locations where DSL and cable aren't
- High cost
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Comparison of Connection Types
T1 and DS3 + High-speed to very-high-speed connections,
can transmit both voice and data - High cost that may be mileage-dependent
Frame relay and ATM + Use virtual circuits to simulate more inter-
office connections than are physically present - High cost normally affordable only by mid- to
large-scale enterprises
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Voice Over IP
Voice over IP – allows you to send voice communications over the Internet and avoid long-distance toll charges
No long-distance calling cost
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NETWORK COMMUNICATIONS MEDIA
Communications media – the paths in a network over which information travels
Wired communications media – transmit information over a closed, connected path
Wireless communications media – transmit information through the air
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Wired Communications Media
Twisted-pair cable – a bundle of copper wires for transmitting voice or data
Cat 5 and Cat 5e are common for modern networks
Coaxial cable (coax) – one central wire surrounded by insulation, a metallic shield, and a covering of insulation
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Wired Communications Media
Optical fiber – uses a very thin glass or plastic fiber through which pulses of light travel
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Wireless Communications Media
Infrared – uses red light to send and receive information
Wi-Fi or Wireless Fidelity - a standard for transmitting information in the form of radio waves over distances of about 100 feet With directional antennas, the distance can be
increased to several miles Wi-Fi hotspots – sites that offer wireless
Internet access for your laptop or tablet.
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Wireless Communications Media
Bluetooth – a standard for transmitting information in the form of short-range radio waves over distances of up to 30 feet and is used for purposes such as wirelessly connecting a cell phone to a computer
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Wireless Communications Media
Microwave – a type of radio transmission Repeater – receives a radio
signal, strengthens it, and sends it on
Satellite – microwave in space where the signal shoots up to a satellite above the earth and is reflected down again.
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Wireless Communications Media
Communications Satellite – microwave repeater in space
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NETWORK SECURITY
The four principles of network security are:
1. Confidentiality2. Authenticity3. Integrity4. Availability
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NETWORK SECURITY
Confidentiality – information can be obtained only by those authorized to access it Bank statements, credit reports,
employee evaluations Threatened by capture of network
transmissions and easily-guessed passwords
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NETWORK SECURITY
Authenticity – information really comes from the source it claims to come from Military orders, medical diagnoses,
stockbroker directions Threatened by fraudulent e-mails
and misspellings of popular Web site names
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NETWORK SECURITY
Integrity – information has not been altered Bank balance, corporate Web site,
prescriptions, credit card charges Threatened by forged network
transmissions and faulty server software
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NETWORK SECURITY
Availability – a service or resource is available when it's supposed to be Mail-order Web site, corporate e-
mail server Threatened by network failures,
faulty server software, and high volumes of malicious network traffic
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Firewalls & Intrusion Detection Systems
Firewall – protects a computer from intruders
Intrusion detection system (IDS) – watches for and reports intrusion attempts
Intrusion prevention system (IPS) – type of IDS that also takes action against intrusion attempts
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Encryption
Encryption – scrambles data so you can't read it without having the decryption key
Virtual Private Network (VPN) – encrypts all network transmissions between two endpoints to protect confidentiality and integrity of data
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Malware
Malware – software designed to harm your computer or security
1. Virus – software written with malicious intent to cause annoyance or damage
2. Worm – spreads itself from computer to computer via e-mail and other network traffic
3. Spyware – collects information about you and reports it to someone else without your permission