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Appendix C Networking www.pearsoned.ca/jessup
Robert Riordan, Carleton 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)
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
Communication Pathway
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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 phone- cable speeds
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Network Types Local Area Network
Local Area Network (LAN) 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 (PAN) An emerging
technology that uses wireless communication to
exchange data between commputing 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 users 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 their multiple
combinations of hardware and software
File Services (a) The capabilities that networked
computers share through their multiple
combinations of hardware and software
Print Services (b) The capabilities used to
control and manage users 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 Transmission Media
Transmission Media The physical pathway to send
data and information between two or more entities
on the network. Characteristics of the media
include the following
Bandwidth Is the transmission capacity of a
communications channel or computer, measured in
megabits per second (Mbps) (amount of binary data
transmitted per second)
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Networking Fundamentals Media (Cable)
Twisted Pair (TP) Two or more pairs of insulated
copper wires twisted together and may be shielded
(STP) or unshielded (UTP). It is the lowest
capacity of the cable options
Coaxial (COAX) Contains a solid inner copper
conductor surrounded by insulation and outer
braided copper or foil shield. It is higher
capacity than twisted pair
Fiber-Optic Made of light-conducting glass or
plastic core, surrounded by more glass, called
cladding, and a tough outer sheath. It is high
capacity and used in high speed backbones
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Networking Fundamentals Media (Cable)
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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 (Microwave)
Microwave A high frequency radio signal that is
sent through the air using either terrestrial
(earth-based) or satellite systems
Terrestrial Microwave A line-of-site technology
(unobstructed) used to cross inaccessible terrain
or to connect buildings where cable installation
would be expensive. Attenuation is low over
short distance but higher over longer distances,
and high winds, heavy rain, EMI and eavesdropping
are also problems
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Networking Fundamentals Media (Microwave)
Satellite Microwave A line-of-site technology
that uses relay stations to transfer signals
between antennae located on earth and a satellite
orbiting the earth. It can be used to access very
remote locations and, like a terrestrial
microwave, attenuation, EMI and eavesdropping are
also problems
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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 (Media Access
Control)
Media Access Control The set of rules that govern
how a given node or workstation gains access to
the network to send or receive information.

• Media Access Control Types
• Distributed Access Control the most common
  method of distributed access control is token
  passing. This method uses a constantly
  circulating electronic token (a small packet of
  data) to prevent collisions and give workstations
  equal access to the network
• Random Access Control the most common method of
  random access control is called carrier sense
  multiple access/collision detect (CSMA/CD). In
  CSMA/CD each workstation listens to the network
  to determine whether a message is being
  transmitted. If quiet, the workstation transmits
  its message otherwise it waits

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Network Hardware and Software (Network Topologies)
Network Topologies Refers to the shape of a
network and comes in three types
Star Network The network is configured in the
shape of a star with all nodes or workstations
connected to a central hub, or concentrator,
through which all messages pass
Ring Network The network is configured in the
shape of a circle with each node connecting to
the next node. Messages travel around the circle
in one direction. Each node examines the message
and uses it or regenerates it and passes it to
the next node
Bus Network The network is configured in the
shape of an open-ended line with all nodes or
workstations connected to the bus individually.
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Network Hardware and Software (Network Topologies)
Star Network
Bus Network
Ring Network
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Network Hardware and Software (Protocols)
Protocols Agreed-upon formats for transmitting
data between connected computers
Open Systems Interconnection (OSI) Is a protocol
that represents a group of tasks (below) as seven
successive layers that allow computers to
communicate
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Network Hardware and Software (Protocols)
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Network Hardware and Software (Protocols)
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Network Hardware and Software (Hardware)
Connectivity Hardware The hardware that allows
computers to be physically connected to different
types of networks

• Common Connectivity Hardware
• Connectors
• Network Interface Cards (NICs)
• Modems
• Repeaters
• Hubs
• Bridges
• Multiplexers
• Routers
• Brouters
• Channel Service Units
• Gateways

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Network Hardware and Software (Hardware)
Connectors Used to terminate cables in order to
be plugged into a network interface card or
another network component
Network Interface Card (NIC) A PC expansion board
with its own unique identifier that plugs into a
computer allowing it to be connected to a network
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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 computers digital signals
to analog and back again for the receiving
computer
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Network Hardware and Software (Hardware)
Hub A central point of connection between media
segments enabling network extension to
accommodate more PCs
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
Bridge Used to connect two different LANs or two
segments of the same LAN by forwarding traffic
between segments
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Network Hardware and Software (Hardware)
Repeater A network device used to regenerate or
replicate a signal as it weakens (attenuates)
while traveling on a network
Hub A central point of connection between media
segments enabling network extension to
accommodate more PCs
Bridge Used to connect two different LANs or two
segments of the same LAN by forwarding traffic
between segments
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
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Network Hardware and Software (Hardware)
Multiplexer Used to share a communications line
among a number of users by converting and
combining signals from multiple users for
simultaneous transmission over a single line
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