Transcript Networking - Jui-Sheng (Rayson) Chou, PE, Ph.D.

Lecture 6: Networking
J. S. Chou, P.E., Ph.D.
National Chung Cheng University
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Human Communication
Messages
Human communication involves the sharing of information
between senders and receivers. The information is shared
in the form of a message
Sender
Initiates the message
by formulating the
message content in
the brain and coding
the message in a
form that can be
communicated to the
receiver (e.g. voice)
Communication
Pathway
Receiver
Uses their receiving
mechanism (e.g. eyes,
ears) to receive the
encoded message
and then attempts to
decode its content or
requests the message
be resent
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Human Communication Example
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Requirements for Communication (Computer)
Senders and Receivers
There must a be a sender and a receiver with something
to share via a message to facilitate communication
Communication Medium
A medium must exist between the sender and receiver
over which the message travels (e.g., a cable)
Protocols
Procedures, rules, or standards must be followed by
computers when sending or receiving data
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Communication (Human versus Computer)
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Computer Networks
Centralized Computing (1970s)
The centralized computing model utilizes a central
computer (mainframe) connected to terminals with all
processing being done on the central computer
Distributed Computing (1980s)
The use of small computers networked together allowing
users to perform a subset of tasks that in aggregate are
equal to that of a centralized computer while also being
able to share information between those computers
Collaborative Computing (1990s)
A synergistic form of distributed computing in which two
or more networked computers are used to accomplish a
common processing task where they are not only sharing
data but also sharing processing responsibilities
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Types of Computing
Distributed Computing
Centralized Computing
Collaborative Computing
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Types of Networks
Networks
Most networks utilize a combination of computing
models that have evolved over time and are connected by
one or more of the following network types:
• Private Branch Exchange (PBX)
• Local Area Network (LAN)
• Wide Area Network (WAN)
• Global Networks
• Enterprise Network
• Value-added Network (VAN)
• Metropolitan Network (MAN)
• Personal Area Network (PAN)
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Private Branch Exchange
PBX
A telephone system
serving a location by
connecting one
telephone line to
another then to an
outside telephone
network. Can also
connect PCs, fax,
but at low phonecable speeds
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Network Types – Local Area Network
Local Area Network
A computer network that spans a relatively small area
allowing all computer users to connect with each other to
share information and peripheral devices (e.g., printers)
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Types of Networks – Wide Area Networks (WAN)
Wide Area Networks (WANs)
A computer network that spans a relatively large area and
is typically used to connect two or more LANs using
different kinds of hardware and transmission media to
cover large distances efficiently
Global
A WAN that spans multiple countries and may include
the networks of several organizations (e.g. the Internet)
Value-added Network (VAN)
A medium-speed, third-party-managed network that is
economical as it is shared by multiple customer
organizations that lease lines rather than investing in
dedicated network equipment
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Types of Networks – Wide Area Networks (WAN)
Enterprise Network & MAN
Enterprise
A WAN that is the result of
connecting the disparate
networks of a single
organization
Metropolitan Area (MAN)
A WAN network of limited
geographic scope, typically
in a city-wide area that
combines both LAN and
high-speed fiber-optic
technologies
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Types of Networks – Personal Area Network (PAN)
Personal Area Network
An emerging technology that uses wireless
communication to exchange data between commuting
devices using short-range radio communication
(Bluetooth), typically within an area of ten meters
Bluetooth
Is the enabling technology of the Personal Area
Network and is a specification for personal networking
of desktop computers, mobile phones, pagers,
portable stereos, and other handheld devices
developed by its founders Ericsson, IBM, Intel, Nokia,
and Toshiba
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Networking Fundamentals – Servers and Clients
Network
A network consists of three separate components: servers,
clients and peers
Server
Any computer on a
network that makes
access to files, printing,
communication, and
other services available
to users on the network
Client
Any computer, such as a user’s workstation or a PC on the
network, or software application such as word processing
program that uses services provided by the server. A client
only requests service and usually has only one user
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Networking Fundamentals – Peers
Peer
A computer that may both request and provide services
Peer-to-Peer Networks (P2P)
Enables any computer or device on the network to provide
or request services with all peers having equivalent
capabilities and responsibilities (e.g., Napster)
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Networking Fundamentals - Network Services
Network Services
The capabilities that networked computers share through
the multiple combinations of hardware and software
File Services (a)
The capabilities that
networked computers
share through the multiple
combinations of hardware
and software
Print Services (b)
The capabilities used to
control and manage
user’s access to network
printers, plotters, fax
equipment, etc.
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Networking Fundamentals - Network Services
Message Services (c)
The capabilities that
include storing, accessing,
and delivering of text,
binary, graphic, digitized
video and audio data
Application Services (d)
The capabilities that run
software for network
clients and enable
computers to share
processing power
Network Operating System (NOS)
Is software that controls the network enabling computers to
communicate by enabling network services
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Networking Fundamentals – Media (Wireless)
Wireless
A communication mechanism that has no physical
transmission media, hence the name wireless, that
works by transmitting electromagnetic signals through
the air. Types of wireless media include:
• Infrared line of sight
• High-frequency radio
• Microwave methods
Infrared Line of Sight
Uses high-frequency light waves to transmit data on
an unobstructed path between nodes – computers or
some other device such as a printer – on a network up to
24.4 meters (i.e. most electronics remotes use this
infrared light) and are susceptible to attenuation, EMI,
eavesdropping, high-intensity light, and smoke
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Networking Fundamentals – Media (Wireless)
High-Frequency Radio
A fast transmission medium for distances up to 40 kilometers,
depending on obstructions. Attenuation is very low but is
susceptible to EMI and eavesdropping. Applications of this
technology include pagers, cellular phones, and Wi-Fi
Pagers
A one way, wireless messaging system in multiple types
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Networking Fundamentals – Media (Wireless)
Cellular Phone
A two-way wireless communication that assigns unique
frequencies to calls and can transmit in analog or digital
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Networking Fundamentals – Media (Wireless)
Wireless LANs or
Wireless Fidelity (Wi-Fi)
Based on a standard
called 802.11, this
technology enables
multiple computers to
share Internet access,
files, and peripheral
devices
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Networking Fundamentals – Media (Wireless)
Wireless Media Benefits and Drawbacks
Comparisons of Wireless Media
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Network Hardware and Software (Hardware)
Modem (Modulator/Demodulator)
Enables computers to connect and transmit data over
phone lines by converting the sending computer’s digital
signals to analog and back again for the receiving computer
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Network Hardware and Software (Hardware)
Router
An intelligent device used to connect two or more
individual networks. When it receives a signal, it looks up
the address and passes it to the appropriate network
Brouter
Short for bridge router and provides the functions of both
Channel Service Unit
A device that acts as a buffer between a LAN and a public
carriers WAN to ensure signals placed on the public lines
are appropriately timed and formed for the network
Gateways
This device performs a protocol conversion so that
different networks can communicate even though they
speak different languages
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