This document discusses communications and networks. It describes different types of communication channels including twisted pair cable, coaxial cable, fiber-optic cable, radio frequency, microwave, satellite, and infrared. It also discusses connection devices like modems and different connection services such as DSL, cable, satellite, and cellular. The document defines key networking terms and describes network architectures like star topology, tree/hierarchical topology, and mesh topology. It also discusses strategies like client/server networks and peer-to-peer networks. Finally, it covers organizational networks, internet technologies, network security, and careers in IT like network administrators.

1. GROUP 2
Nurul Aminah Thaqif
Nurul Nadiah binti Ramli
Aminah binti Mustaffa
Muhammad Thaqif bin Md Rajab

2. Chap 9:COMMUNICATIONS AND
NETWORKS

3. Introduction

4. COMMUNICATIONS

6. COMMUNICATION CHANNELS
-Twisted-pair cable
-Coaxial cable
-Fiber-optic cable
-Radio frequency
-microwave
-satellite
-infrared

7. COMMUNICATION CHANNELS
CHANNEL
DESCRIPTION
Twisted pair
Twisted copper wire,used for standard telephone lines and
Ethernet cables.
Coaxial cable
Solid copper core,more than 80 times the capacity of twisted
pair.
Fiber-optic cable
Light carries data ,more than 26,000 times the capacity of
twisted pair.
Radio frequency
Radio waves connect wireless devices including cell phones
and computer components.
Microwave
High-frequency radio waves ,travels in straight line through
the air.
Satellite
Microwave relay station in the sky ,used by GPS devices.
Infrared
Infared light travels in a straight line.

8. CONNECTION DEVICES
MODEMS
-modula-demodulator.
-Modulation: Process of converting
digital to analog and demodulation
is vice versa.
-Enable digital microcomputers to
communicate across different
media,including telephone wires,
cable lines, and radio waves.
CONNECTION SERVICE
-For years, individuals relied on dial-up
services using existing telephones and
telephone modems to connect to
internet. This type of service has been
replaced by higher-speed connection
services including DSL,cable,satellite,
and cellular services.
TYPES:
-Telephone modem
-DSL(digital subscriber line)
-Cable modem
-Wireless modem
TYPES:
-Digital subscriber line(DSL) service
-Cable service
-Satellite connection service
-cellular service

9. Description types of modems
Telephone modem
-Used to connect a computer directly to a telephone line.
-internal : system board –external : system unit
DSL(digital subscriber line) modem
-Uses standard phone lines to create a high- speed connection directly to
phone company’s offices.(usually external-connect to system unit using
USB or Ethernet ports.
Cable modem
-Uses the same coaxial cable television.
-creates high- speed connections like DSL using system unit’s USB or Ethernet
port.
Wireless modem
-Known as WWAN(wireless wide area network).
- Usually plug-in USB or ExpressCard device that provides very portable highspeed connectivity.

10. Description of Connection Service
Digital subscriber line(DSL) service
-Provided by telephone companies using existing telephone lines to provide
high-speed connections.
Example:ADSL(asymmetric digital subscriber line)-faster than dial-up
Cable service
-Provided by cable television companies using their existing television cablesfaster than DSL
Satellite connection services
-Use satellite to provide wireless connections-slower than DSL and cable
modems-but are available almost anywhere using satellite-receiving disk.
Cellular services
-3G or 4G to provide wireless connectivity to the internet-not fast as the
other services but are rapidly growing in popularity for mobile
devices(phones and other portable devices.

11. DATA TRANSMISSION
Measurement of the width or capacity of the communication channel.
Voiceband
Medium band
Broadband
Baseband

12. DATA TRANSMISSION
A set of communication rules for the exchange of
information.
Identification
Packetization

13. Networks
A communication system that connects two or more computers so
that they can exchange information and share resources.

14. TERM
DESCRIPTION
NODE
Device that is connected to a network. It could be a computer,
printer, or data storage device
Clients
A node that requests and uses resources available from other
nodes. Typically, a client is a user’s microcomputer.
Server
A node that shares resources with other nodes.
Directory server
A specialized server that manages resources ,such as user
accounts, for an entire network.
Host
Any computers system that can be accessed over a network.
Switch
Central node that coordinates the flow of data by sending
messages directly between sender and receiver nodes.
(NIC) Network
interface cards
Expansion cards located within the system unit that connect the
computer to a network -LAN adapter
(NOS) Network Control and coordinate the activities of all computers and other
operating system devices on network.
Network
administration
A computer specialist responsible for efficient network operations
and implementation of new networks.

16. NETWORK ARCHITECTURE
Describe how network is arranged and
how resources are coordinated and
shared.

17. TOPOLOGIES
Describe the physical arrangement of the network.

18. • Star network -each device is connected directly to a
central network switch.

19. •Tree/hierarchical network –each device is connected
to a central node, either directly through one or more other
devices.

20. • Mesh network -each device connected to more than one
other device

21. STRATEGIES
Define how information and resources are shared
Strategy
Description
Client/server
networks
Clients request services; server provide services and
coordination; efficient network management software;
expensive.
Peer-to-peer
networks
All nodes act as clients and servers ;easy and inexpensive;
lacks security controls.

22. Organizational Networks
Internet Technologies
Intranet
-private network within an
organization that resembles the
internet.
-use browsers, Web sites, and Web
pages
Extranet
-private network that connects
more than one organization.
-to allow suppliers and others
limited accesses to their networks.
-to increase efficiency and reduce
costs.
Network Security
Firewall
-consists of hardware and software that
control access to a company’s intranet
and other internal networks.
Intrusion detection system (IDS)
-work with firewalls to protect an
organization’s network.
Virtual private networks(VPN)
-create secure private connection
between a remote user and an
organization’s internal network.

23. Careers in IT
Network administrators
-manage company’s LAN and WAN networks.
-responsible for design, implementation, and maintenance of
networks
-Responsibilities include maintenance of both hardware and software
related to a company’s intranet and Internet networks.