1Lesson 2—Networking BASICS
Lesson 2—Networking BASICS2
Types of Networks
• There are two types of
networks by which
information is transmitted:
– circuit switched networks
– packet switched networks
Lesson 2—Networking BASICS3
Circuit Switched Network
• There is a dedicated and direct physical
connection between sender and receiver.
• No other transmissions can take place while
the connection is active.
• Once the transmission is ended, other
connections can be made with other devices.
• It is ideal for voice communications because
there are no interruptions from other devices
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Packet Switched Network
• This network requires data transmission be broken
into smaller units called packets.
• Each packet is sent independently through the
• It is used for data transmission because data is not
as time-sensitive as voice communication.
• It allows multiple devices to share one line or
• It facilitates error correction.
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• There are two ways that a
signal is sent across a
– baseband signaling
– broadband signaling
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• Sends one data signal across the network
• Entire capacity of the media is used for the
one data signal
• Signals are transmitted in a digital format
• Many devices can send and receive across
the medium, but only one at a time
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• Divides the cable into several different
• Signals are transmitted at different
frequencies in an analog mode
• Allows many different signals to be sent
simultaneously on a single cable
• Signal sent in only one direction
• Used for computer network data
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Factors Affecting Transmissions
• The flow of a signal down the
network media can become
• Common types of distortions are
attenuation and interference.
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• Loss of signal power
• Measured by the decrease
in decibels (db) over a
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• Interference is caused when a strong external signal
interferes with a signal.
• Radio frequency interference (RFI) - interference
caused by broadcast signals from a radio or
• Electromagnetic interference (EMI) - motor or
source of intense electrical activity creates an
electromagnetic signal that interferes with a data
• Near end crosstalk (NEXT) and Far end crosstalk
(FEXT) - interference from another data signal being
transmitted on adjacent wire.
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• This cable uses a thin cylinder of glass to
send light impulses.
• The cable consists of a strand of glass (core)
surrounded by a glass tube (cladding).
• Single mode - one light source flashes a light
down the cable.
• Multimode - supports many simultaneous
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• Transmission is sent and received through
• Less expensive than copper or fiber optic
• Allows the user to move freely around the
office or campus and still remain connected
to the network
• Fastest-growing segment of network media
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• Infrared transmits data using infrared (IR)
• IR shares many of the same properties as
visible light .
• Radio frequency signals can be transmitted
over radio waves similar to local radio station
• The signal comes in at a lower power level
and does not reach as far.
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Network Interface Card
• The NIC serves as the connection between
the personal computer and the network
• It connects to the computer on its base by
plugging into an expansion slot of the
• Another connection is accessible from the
outside of the computer and has connections
for the cables to plug into the network.
Lesson 2—Networking BASICS22
Network Interface Card
• Changes from parallel to
• Creates packets
• Determines when to send
• Transmits packet