Download Networks..

Foundations of information
systems :
BIS 1202
Lecture3
Telecommunications, Networks, and
the Internet
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Learning Objectives
By the end of this lecture students should;
Identify and describe the fundamental
components of a telecommunications system
including media and hardware devices
Identify several network types and describe the
uses and limitations of each
Name three basic processing alternatives for
organizations that require two or more computer
systems and discuss their fundamental features
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Learning Objectives
Understand how telecommunication has
improved business
Factors affecting communication in
telecommunications
Understand computer networks and
protocols
Understand network hardware and how the
internet works
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Telecommunications
 The communication of information by
electronic means, usually over a distance.
 Telecommunications has improved business in
three main ways:
Better communication
Higher efficiency
Better distribution of data
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Telecommunications system
A telecommunication system is a collection of
compatible hardware and software arranged to
communicate from one location to another.
Essential components of a telecommunication
system
•Computers-to process information
•Terminals or any input/output devices that
send or receive data.
•Communication channels-links by which
data or voice are transmitted between sending
and receiving devices in a network
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Telecommunications system
Essential components of a telecommunication system
End processors which provide support functions for data
transmission and reception
E.g. modem and decoders
•Communications software, which controls input and
output activities and manages other functions of the
communications network
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Telecommunications in Daily Use
• Cellular Phones
• Videoconferences
• Voice Mail
• fax
• Web-Based Electronic Commerce
• Worldwide Peer-to-Peer File Sharing
– Napster, Gnutella, Morpheus
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Communication Direction
• Simplex
– One-way in one direction e.g. antenna
• Half-Duplex
• Systems that provide communications in
both directions, but only one direction at a
time. E.g. walkie talkies
• Full-Duplex-allows communication in both
directions and allows this to happen
simultaneously e.g. telephones
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Communication Direction (Cont.)
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Factors affecting Telecommunications
• Communications medium
– Physical medium through which data can be communicated
– Telephone lines, television cables
• Capacity
– Speed at which data are communicated
– Also called the transmission rate
– It is often called “bandwidth”(the rate at which electronic
signals can travel through a medium)
• Bandwidth is measured in bits per second
(bps)
– The greater the capacity, the faster the transmission
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Bandwidth and Media (Cont.)
• Bandwidth
– Narrowband is low speed
– Broadband has greater capacity
• Media
– A medium is any means by which data can be transmitted
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Telecommunications Media
Twisted Pair
– Telephone line made of a pair of copper wires twisted to reduce
electromagnetic interference (EMI)
Coaxial Cable
Commonly used for cable television transmission
– More expensive than twisted pair
– Greater transmission rate than twisted pair
– Much less susceptible to EMI
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Telecommunications Media conts..
Microwaves : High-frequency, short radiofrequency (RF) waves
– Terrestrial microwave
– Satellite microwave
Optical Fiber:
– Fiber-optic technology uses light instead of
electricity to transmit data
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Digital and Analog Data
• Analog data is represented as continuous waveforms
– Example: audio tape
• Digital data is computer data – sequence of binary 0s
and 1s:
– Example: data stored on the hard drive
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Modulation (Cont.)
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Computer networks
 A computer network can be defined as: a
communications system that links two or more
computers and peripheral devices and enables
transfer of data between the components’.
 Telecommunications: the communication of
information by electronic means, usually over some
distance.
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What is a Computer Network?
Two or more computers or communications devices connected by transmission
media and channels and guided by a set of rules for communication purposes
that allow users to communicate with each other and share applications and data.
Hardware:
Computer
Network card
Routers
Modem …
Software:
Network OS
Utilities …
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Media:
Cable
Wire
Microwave …
Network Design:
Logical layout
Physical layout …
Components of aBIS1100
Computer Network
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Categorization of Networks..
A number of different ways exist to organize telecommunications
components to form a network and hence provide multiple ways of
classifying/categorizing a network
By size:
• Local Area Networks (LANs)
•
Wide Area Networks (WANs)
• Metropolitan Area Network (MAN)
By capability:
•
Client/Server Networks (Server-Based Networks)-Resources are
shared with the help of a centralized computer
•
Peer-to-Peer Networks –computers share equally with out having to
rely on a server
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Client/Server
Pros:
 Very secure
 Centralized servers easy to manage
 Physically centralized
 Secure OS
 Better performance
 Centralized backups
 Reliability
Cons:
 Require professional administration
 More hardware intensive
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Peer-to-Peer (p2p)
Computers on the network communicate with each
others as equals and each computer is responsible for
making its own resources available to other
computers on the network.
Pros:
 Uses less expensive computer networks
 Easy to administer
 No NOS (network operating system) required
 Shared resources – some machine will have what you
need
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Peer-to-Peer (p2p)Conts..
Cons:
 Not very secure
 Individual user performance easily affected
 Tragedy of the commons – no guarantee others
will administer their resources properly.
 Hard to back up.
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Categories of Networks
 LANs (Local Area Networks)
 Networks within a building, or within a group of adjacent
buildings(the interconnection of different network devices
with in a small geographical area)
 WANs (Wide Area Networks)
 Networks that cross organizational boundaries or reach
outside the company
(The interconnection of different network devices with in a wide
geographical area)
 Metropolitan Area Network (MAN)
 Covers a geographic area the size of a city or suburb. The
purpose of a MAN is often to bypass local telephone
companies when accessing long-distance service.
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Network Topologies
• One way of describing networks is by the way
their components are connected, or topology.
Physical layout of the nodes in a network
– Star-consists of a central host computer connected to a number of
smaller computers or terminals
– Ring-each computer on a network can communicate directly with
another computer-does not rely on a central host computer.
– Bus-links a number of computers by a single circuit made of
twisted wire, coaxial cable, or fiber optic cable
– Tree-very many star networks interconnected together.
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Network Topology
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Network Selection Criteria
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Size of the organization
Level of required security
Level of available administrative support
Amount of network traffic
Needs of the network users
Budget for building the network
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Networking Hardware
 Hub. device for connecting multiple twisted pair or fiber
optic Ethernet devices together and making them act as a
single network segment
 Switch. Interconnects different network devices together.
 Router .Interconnects networks based on different rules or
protocols
 Network Interface Card (NIC). computer hardware
component designed to allow computers to communicate
over a computer network
 Bridge. A device that interconnects different network
segments.
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Networks: Pros and Cons
Pros
• Resource sharing
– Printers, CD-ROMs, computers
.Software.
• Data and information sharing
• Communications- email.
-voice and video.
-E-learning. –VOIP.
• Reduced Cost
• On-line services
• Groupware
Cons
• Security risks increase with
networks
• Complexity is associated
with networks
• Investment is high and
return on it may not happen
– Software that supports group efforts
over a network
• Electronic data interchange
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The Internet
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The Internet
• A network of networks
(interconnection of different networks for the purpose of
sharing information and data)
• Popular uses
–E-mail
–Instant messaging
–Browsing the World Wide Web
–Newsgroups and chat rooms
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Internet Service Providers
• Any company that provides individuals or
organizations with access to the Internet
• Most charge a monthly fee
• Many ISPs and online services
– Offer broadband Internet access through digital
subscriber lines (DSLs), cable, or satellite
transmission
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Network Protocols
• Communication protocols
– Rules governing the communication
between computers or between computers
and other computer-related devices
• Network protocols-Rules governing a network
of devices
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Protocols (Cont.)
 LAN Protocols
 Ethernet
 Token passing
 WAN Protocols
 OSI (Open Systems Interconnection)
 Standard protocol model
 Seven layers
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Summary
• Telecommunications concepts and terminology
• Communication within a computer system and
among computers
• Telecommunications media and devices
• Network layouts and protocols
• Telecommunications impact on operations
• Telecommunications developments and speed
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Review questions
 List major components of a computer and explain
their functions
 Explain how computers communicate
 Classify computers into major categories, and
identify their strengths and weaknesses
 With examples, Define the most commonly used hardware
terminology.
 Input devices
 Output devices
 Memory
 Cache memory
 EPROM
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questions (Cont.)
 Identify and evaluate key criteria when deciding what
computers or related devices to purchase
 Explain the controversy regarding the health hazards of
computers
 Evaluate hardware so that you can harness it to improve
managerial processes
 Explain why successful managers must be familiar with
telecommunications concepts and terminology
 Describe the principles of communication within a computer
system and among computers
 Identify the major media and devices used in
telecommunications
 differentiate between logical control unit and Arithmetic Logic
Units
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questions (Cont.)
 How are networks used to solve business problems?
 List the main components of a network?
 Explain three main Network Topologies?
 Why do businesses use networks to share hardware?
 List and explain the functions of different network
layouts and the concept of protocols
 Explain how telecommunications can improve
operations in organizations
 List the types of transmission media that are
available?
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