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Network interface cards (NICs) connect devices to wired or wireless networks at the physical layer. The physical layer transports data link layer frames by encoding them as signals and transmitting them onto the local media. It accepts complete frames, encodes them as a series of signals, and transmits them. The signals are then received by end devices or intermediate devices. Common physical layer media include twisted pair, coaxial cable, and fiber. Standards bodies like ISO, IEEE, and ITU define physical layer standards.

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25 views5 pages

Untitled2 CC

Network interface cards (NICs) connect devices to wired or wireless networks at the physical layer. The physical layer transports data link layer frames by encoding them as signals and transmitting them onto the local media. It accepts complete frames, encodes them as a series of signals, and transmits them. The signals are then received by end devices or intermediate devices. Common physical layer media include twisted pair, coaxial cable, and fiber. Standards bodies like ISO, IEEE, and ITU define physical layer standards.

Uploaded by

Randeep Singh
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Physical Layer Connection

Network Interface Cards

 Network Interface Cards (NICs) connect a device to


a network.

 Used for a wired connection.

 Wireless Local Area Network


(WLAN) NICs are used for
wireless connections.
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 6
Purpose of the Physical Layer
The Physical Layer
• Provides the means to
transport the bits that
make up a data link
layer frame across the
network media.
• Accepts a complete
frame from the data
link layer and encodes
it as a series of signals
that are transmitted
onto the local media.
• Encoded bits that
comprise a frame are
received by either an
end device or an
intermediate device.

© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 7
Purpose of the Physical Layer
Physical Layer Media

Three basic
forms of
network media

© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 8
Purpose of the Physical Layer
Physical Layer Standards

 International Organization for


Standardization (ISO)

 Telecommunications Industry
Association/Electronic
Industries Association
(TIA/EIA)

 International
Telecommunication Union
(ITU)

 American National Standards


Institute (ANSI)

 Institute of Electrical and


Electronics Engineers (IEEE)

© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 9
Physical Layer Characteristics
Functions
 Encoding
The transition occurs at the
• Method of converting a stream of
middle of each bit period.
data bits into a predefined
"code”.
 Signaling Method
• Method of representing the bits.
• Physical layer standards must
define what type of signal Modulation is the
represents a "1" and what type of process by
signal represents a "0”. which the
• Long pulse might represent a 1 characteristic of
whereas a short pulse represents one wave (the
a 0. signal) modifies
another wave
(the carrier).
© 2016 Cisco and/or its affiliates. All rights reserved. Cisco Confidential 10

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