Chapter 8

8
Chapter
Communications
and Networks
Chapter 8
© 2017 by McGraw-Hill Education. This proprietary material solely for authorized instructor use. Not authorized for sale or distribution in any manner. This document may not be copied, scanned, duplicated, forwarded, distributed, or
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Learning Objectives
1. Explain connectivity, the wireless revolution, and communication

systems.
2. Describe physical and wireless communications channels.
3. Differentiate between connection devices and services, including dial-
up, DSL, cable, satellite, and cellular.
4. Describe data transmission factors, including bandwidth and protocols.
5. Define networks and key network terminology including network
Computing Essentials 2017
interface cards and network operating systems.

6. Describe different types of networks, including local, home, wireless,
personal, metropolitan, and wide area networks.
7. Describe network architectures, including topologies and strategies.
8. Explain the organization issues related to Internet technologies and
network security.
Connectivity
Everyone now has a device that is

connected to Internet
The Wireless Revolution

Single most dramatic change in

connectivity in the past decade is the
widespread use of mobile devices
with wireless Internet connectivity
The Revolution is just beginning
Communication Systems
Electronic systems that transmit data from one

location to another
Basic Elements of Communication
Four basic elements of communication systems
Sending and receiving devices

Computer or a specialized communication device that originates (creates) and accept messages
in the form of data, information, and/or instructions
Connection devices
Interface between sending and receiving device They convert outgoing messages into
packets that travels into the communication channel
Communication channel
Carries the message. It can be wired or wireless
Data transmission specifications

Rules and procedures that coordinate the devices
Communication Channels
Communication channels carry the data from

one computer to another;
essential element of every communication system
Two categories of communication channels

Physical Connections using wire or cable

Wireless Connections
Physical Connections (Cables)
Types of Cables:
https://www.youtube.com/watch?v=qQYiwmamq38
Twisted pair cable: two pairs of copper wire twisted

together
 Used in Standard Telephone lines and Ethernet cables
Coaxial cable: single solid copper core

 high-frequency transmission cable
 Used for Cable TV and Computer Networks
Fiber-optic cable: data is transmitted as light in tiny

glass tubes
 Fastest Cable
 Rapidly twisted pair
Wireless Connections
Wireless connections do not use a solid substance to connect;

No Cable
uses the air itself.
Most use radio waves to communicate
Primary Wireless Technology
Bluetooth (short-range)
Radio communication standard
Wi-Fi (wireless fidelity)

Uses high frequency radio
Microwave
Uses high frequency radio wave signals
line-of-sight communication medium: can transmit
and receive data only where transmit and receive
stations are in view of each other without any sort of
an obstacle between them
Primary Wireless Technology
WiMax - Worldwide Interoperability for Microwave Access

New standard that uses microwave to extend WiFi range
Satellite
Uses satellites as microwave relay stations
Cellular
Use multiple antennae to communication
GPS
Determine geographic location of the devices
Uses satellite communication channel
Connection Device Signals
Types of signals
Analog
continuous electronic
waves. Telephones lines
that were originally
designed for voice
transmissions send and
receive data in the form of

analog signals..
Digital
Digital signals represent
the presence (1) or absence
(0) of an electronic pulse
Connection Device Signals
Modem – modulator-demodulator
Devices need to convert digital signal to analog
Modulation is converting from digital to analog
Demodulation is converting from analog to digital
Transfer rate
Speed in which modems transfer data
Usually measured in megabits per second (Mbps)
Mbps – million (Mega) bits per second
Gbps – billion (Giga) bits per second
Tbps – trillion (Terra) bits per second
Types of Modems
Types of Modems
Digital subscriber line (DSL)
High speed telephone lines
Cable
Uses coaxial cable
Wireless
Also known as WWAN - Wireless wide

area network
Connection Services - Individuals
Digital subscriber line (DSL)
 Uses existing phone lines to provide high speed connection
 ADSL is most widely used type of DSL
Cable
 Uses existing TV cable to provide high speed connection
 Faster than DSL
Satellite connection services

 use satellites to provide wireless connections.
 These can be slower than DSL and cable modems, but are available almost
anywhere using a satellite-receiving disk.
Cellular Services
 use 3G/4G to provide wireless connectivity to the Internet
Fiber Optic Service (FiOS)

 New technology used by Google and Verizon
 faster than cable or DSL, but is not widely available.
Data Transmission
Bandwidth is one of the

factor that affect data
transmission
Bandwidth is the
capacity of a
communication channel.
Categories of bandwidth
Voiceband (or low bandwidth) – standard telephone
Medium band – used in special lines to connect midrange computers and mainframes
as well as to transmit data over long distances
Broadband for DSL, cable, satellite connections to the Internet Using

this type of communications channel, several users can simultaneously
use a single connection for high-speed data transfer.
Baseband for individual connections for computers in close range. Can

transmit one signal at a time
Making IT Work for You ~ Mobile
Internet
Have an “always-on” connection to access e-mail, websites,
cloud services, and apps.
Devices that can keep you always connected
Protocols
Communication rules for exchanging data

between computers
HTTPS – Hypertext Transfer Protocol
Secure
Widely used to protect the transfer of
sensitive data
Protocols - TCP/IP
TCP/IP (Transmission control protocol/Internet

protocol)
Most widely used protocol
Identify sending and receiving devices
breaking information into small parts for
transmission across the Internet.
 Each computer is identified with unique numeric address

called IP (Internet Protocol)
 DNS – Domain name service resolves IP addresses to

names https://www.youtube.com/watch?v=mpQZVYPuDGU
Packetization – is the process of breaking down

data into small parts to be sent or transmitted
across the Internet
Protocols - TCP/IP
Networks
A communication system
that connects two or more
computers so they can
exchange information and
share resources
Specialized Terms in a Network
 Nodes
 Any device connected to a network
 Client
 A node that requests and uses resources from other nodes
 Server
 A node that shares resources with other nodes
 Directory Server
 Specialized server that managers resources
 Host
 Computer system that can be accessed over a network
 Router
 Node that forwards or routes data packets
 Switch
 Central node that coordinates the flow of data
 Network Interface Cards (NIC)
 Expansion card that connects a computer to a network
 Network Operating System
 Control activities of all computers on the network
 Network Administrator
 Computer specialists responsible for network operations
Network Types
https://www.youtube.com/watch?v=4_zSIXb7tLQ
• LAN – Local Area Network. Home network is LAN for a house

• Connection between LANs is called network gateway
• PAN Personal area network. Wireless network to connect immediate
surrounding (cell phones to headsets)
• WLAN – Wireless LAN

• MAN – Metropolitan area Network.
• A network that is frequently used as links between office buildings
that are located throughout a city.
• WAN – Wide Area Network (countrywide or worldwide)
Network Architecture
Network Architecture describes how a computer

network is configured and what topologies and
strategies are used.
Network Topology
Physical arrangement of the network
Each device is called node

Computers are hosts
https://www.youtube.com/watch?v=zbqrNg4C98U
Network Strategy
How the information and resources are shared
Topology - Ring Network
Topology where each device connected

directly to a central network switch
Topology - Star Network
Topology where each device connected

directly to a central network switch
Topology - Tree Network
There is central node is

connected to two or more
subordinate nodes
Other devices are connected
to other subordinate nodes.
Also called hierarchical
Topology - Tree Network
Topology - Mesh Network
Topology that does not use

a specific physical layout
It requires that each node

(host) have more than one
connection to other nodes

(host)
Network Strategies
Client/Server Network
Central computers coordinate and supply
services to other nodes on the network
Server it supplies service to clients
Client requests resources
Handle large networks
Peer-to-Peer (P2P) Network

All nodes have equal authority
Each computer act as both client and server
Advantage: Easy and inexpensive
Disadvantage: No security and common
standards
Organizational Networks
Internet technologies support effective

communication within and between
organizations
Intranet
Private network within an organization
Resembles (looks like) the Internet
Extranet
Private network that connects more than one
organization
Works like the Internet, but provides suppliers
and other trusted partners with limited access to
the organization’s networks
Network Security
Commonly used technologies to ensure network security
Proxy server https://www.youtube.com/watch?v=5cPIukqXe5w

Firewall
 Hardware and software that controls access to network
 It include a special computer called Proxy server that provide communication between
internal network and outside world.
 Protects against external threats

 https://www.youtube.com/watch?v=kDEX1HXybrU
Intrusion detection system (IDS)

 Recognize attack and disable it before intruder can cause damage
Virtual private network (VPN)

 Creates a secure private network connection between your computer and the
organization for remote connection
Intranet, Extranet, Firewall, Proxy
Server
Open-Ended Questions
1. Define communications including connectivity, the wireless revolution, and communication systems.
2. Discuss communication channels including physical connections and wireless communications.
3. Discuss connection devices including modems (DSL, cable, and wireless modems) and connection services (DSL,
ADSL, cable, satellite and cellular connection services).
4. Discuss data transmission including bandwidths (voiceband, medium band, broadband, and baseband) as well as
protocols (IP addresses, domain name servers, and packetization).
5. Discuss networks by identifying and defining specialized terms that describe computer networks.
6. Discuss network types including local area, home, wireless, personal, metropolitan, and wide area networks.
7. Define network architecture including topologies (bus, ring, star, tree, and mesh) and strategies (client/server and
peer-to-peer).
8. Discuss organization networks including Internet technologies (intranets and extranets) and network security
(firewalls, proxy servers, intrusion detection systems, and virtual private networks).

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8

1. Explain connectivity, the wireless revolution, and communication

interface cards and network operating systems.

Everyone now has a device that is

The Wireless Revolution

Single most dramatic change in

The Revolution is just beginning

Electronic systems that transmit data from one

Four basic elements of communication systems

Sending and receiving devices

Data transmission specifications

Communication channels carry the data from

Two categories of communication channels

Physical Connections using wire or cable

Twisted pair cable: two pairs of copper wire twisted

Coaxial cable: single solid copper core

Fiber-optic cable: data is transmitted as light in tiny

Wireless connections do not use a solid substance to connect;

Wi-Fi (wireless fidelity)

WiMax - Worldwide Interoperability for Microwave Access

receive data in the form of

Also known as WWAN - Wireless wide

Satellite connection services

Fiber Optic Service (FiOS)

Bandwidth is one of the

Voiceband (or low bandwidth) – standard telephone

Broadband for DSL, cable, satellite connections to the Internet Using

Baseband for individual connections for computers in close range. Can

Communication rules for exchanging data

TCP/IP (Transmission control protocol/Internet

 Each computer is identified with unique numeric address

 DNS – Domain name service resolves IP addresses to

Packetization – is the process of breaking down

• LAN – Local Area Network. Home network is LAN for a house

• WLAN – Wireless LAN

Network Architecture describes how a computer

Each device is called node

Topology where each device connected

Topology where each device connected

There is central node is

Also called hierarchical

Topology that does not use

It requires that each node

connection to other nodes

Peer-to-Peer (P2P) Network

Internet technologies support effective

Resembles (looks like) the Internet

Commonly used technologies to ensure network security

Proxy server https://www.youtube.com/watch?v=5cPIukqXe5w

 Protects against external threats

Intrusion detection system (IDS)

Virtual private network (VPN)

2. Discuss communication channels including physical connections and wireless communications.

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