Transcript Chapter 1 THE INFORMATION AGE IN WHICH YOU LIVE Changing

Extended Learning Module E
NETWORK BASICS
McGraw-Hill
© 2008 The McGraw-Hill Companies, Inc. All rights reserved.
STUDENT LEARNING OUTCOMES
1.
2.
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.
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).
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STUDENT LEARNING OUTCOMES
3.
4.
Compare and contrast the various Internet
connection possibilities.
Compare and contrast the types of
communications media.
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STUDENT LEARNING OUTCOMES
5.
6.
State the four principles of computer security and
describe how different network security devices
reflect those principles.
Describe client/server business networks from a
business and physical point of view.
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INTRODUCTION
network – two or more computers
connected so that they can communicate with each
other and share information, software, peripheral
devices, and/or processing power
 Computer
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INTRODUCTION
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Basic Principles of Networks

1.
2.
3.
Four main principles
Each computer must have a network interface to
provide a doorway for information
The network usually has at least one connecting
device
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.
2.
3.
An Ethernet network card in each computer or a
wireless card in each laptop
Network cables to transmit signals, or no cables for
wireless
A DSL or cable modem connection and a
broadband/home router
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Network Cards
interface card (NIC) – an expansion card
or PC card that connects your computer to a
network
 Network
Ethernet card – the most common type of network
interface card
 Built into the motherboards of many new computers –
looks like a telephone jack, but wider

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Wired Transmission Media
5 (Category 5) cable – better-constructed
version of phone twisted-pair cable
 Cat
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Wireless Transmission Media
Access Point (WAP) – device that allows
a computer to use radio waves to access a network
 Connects to hub or switch with a cable like a wired
computer
 May be built into broadband router and not require
separate cabling
 Wireless
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Home Internet Service
router or home router – a device to
connect computers together to share DSL or cable
Internet service in a home or small office
 Broadband
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
– a device that connects computers into a
network and repeats all transmissions to every
connected computer
 Hub
Only one computer can transmit at a time
 All computers see every message
 Can have collisions when two computers try to
transmit at the same time

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NETWORK COMPONENTS
– a device that connects computers and
repeats transmissions only to intended recipient
 Switch
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
– a device that connects subnetworks
(subnets) of a larger network
 Router
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
or hubs
 Corporate routers generally require separate switches
or hubs
 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 proximity 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
– 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
 Broadband
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Dialup Connection
– 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
 Modem
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Digital Subscriber Line (DSL)
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
 Digital
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Cable Modem
modem – uses your TV cable to deliver an
Internet connection
 Cable
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Satellite Modem
modem – delivers Internet access from
satellite dish
 Satellite TV and modem may share same dish or
may be separate
 Connects to computer or broadband router like
cable modem
 Satellite
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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 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 always-on
 - Connection shared with 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 largescale enterprises

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Voice Over IP
over IP – allows you to send voice
communications over the Internet and avoid longdistance toll charges
 No long-distance calling cost
 Voice
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NETWORK COMMUNICATIONS
MEDIA
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
 Communications
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Wired Communications Media
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
 Twisted-pair
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Wired Communications Media
fiber – uses a very thin glass or plastic fiber
through which pulses of light travel
 Optical
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Wireless Communications Media
– uses red light to send and receive
information
 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 or PDA
to a computer
 Microwave – a type of radio transmission
 Infrared

Repeater – receives a radio signal, strengthens it, and
sends it on
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Wireless Communications Media
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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.
2.
3.
4.
Confidentiality
Authenticity
Integrity
Availability
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NETWORK SECURITY
– information can be obtained only by
those authorized to access it
 Confidentiality
Bank statements, credit reports, employee evaluations
 Threatened by capture of network transmissions and
easily-guessed passwords

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NETWORK SECURITY
– information really comes from the
source it claims to come from
 Authenticity
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
– a service or resource is available when
it's supposed to be
 Availability
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
– 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
 Firewall
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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
 Encryption
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Firewalls & Intrusion Detection
Systems
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Malware

Malware – software designed to harm your
computer or security
1.
2.
3.
Virus – software written with malicious intent to
cause annoyance or damage
Worm – spreads itself from computer to computer
via e-mail and other network traffic
Spyware – collects information about you and
reports it to someone else without your permission
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CLIENT/SERVER SOFTWARE
MODEL
network – a network in which one or
more computers are servers and provide services to
the other computers, called clients
 Client/server
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Client/Server: A Business View

Client/server networks differ according to
1.
2.
3.
Where the processing for the presentation of
information occurs
Where the processing of logic or business rules
occurs
Where the data management component (DBMS)
and information (database) are located
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Client/Server: Model 5
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Five Models of Client/Server
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Five Models of Client/Server
1.
Distributed Presentation

2.
Remote Presentation

3.
The server handles almost all functions, including a
major portion of the presentation
The client handles all presentation functions
Distributed Logic

The server handles all data management, the client
handles all presentation formatting, and the logic
processing is shared
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Five Models of Client/Server
4.
Remote Data Management

5.
The server handles data management only, and the
client processes business rules and formats the
presentation of results
Distributed Data Management

The client handles all presentation formatting and
business rule processing, and both the server and
client share data management duties
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