Extended
Learning Module
E
Network Basics
© McGraw-Hill Companies, Inc., McGraw-Hill/Irwin
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.
4.
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).
Compare and contrast the various
Internet connection possibilities.
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STUDENT LEARNING
OUTCOMES
5.
6.
Compare and contrast the types of
communications media.
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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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
radio waves for wireless
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) – highspeed 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 longdistance 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 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 interoffice connections than are physically present
- High cost normally affordable only by midto 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
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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

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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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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