Modulo 4 cisco ccna v7 para estudiantes d

Module 4: Physical Layer
Instructor Materials
Introduction to Networks v7.0
(ITN)

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© 2019, 2021 Cisco and/or its affiliates. All rights reserved. Cisco Confidential
To facilitate learning, the following features within the GUI may be included in this module:
What to Expect in this Module
Feature Description
Animations Expose learners to new skills and concepts.
Videos
Expose learners to new skills and concepts.
Check Your
Understanding(CYU)
Per topic online quiz to help learners gauge content understanding.
Interactive Activities A variety of formats to help learners gauge content understanding.
Syntax Checker
Small simulations that expose learners to Cisco command line to practice
configuration skills.
PT Activity
Simulation and modeling activities designed to explore, acquire, reinforce, and
expand skills.

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Feature Description
Packet Tracer Physical
Mode Activity
These activities are completed using Packet Tracer in Physical Mode.
Hands-On Labs Labs designed for working with physical equipment.
Class Activities These are found on the Instructor Resources page. Class Activities are
designed to facilitate learning, class discussion, and collaboration.
Module Quizzes
Self-assessments that integrate concepts and skills learned throughout the
series of topics presented in the module.
Module Summary Briefly recaps module content.
What to Expect in this Module (Cont.)
▪ To facilitate learning, the following features may be included in this module:

Module 4: Physical Layer
Introduction to Networks v7.0
(ITN)

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Module Objectives
Module Title: Physical Layer
Module Objective: Explain how physical layer protocols, services, and network media support
communications across data networks.
Topic Title Topic Objective
Purpose of the Physical Layer Describe the purpose and functions of the physical
layer in the network.
Physical Layer Characteristics Describe characteristics of the physical layer.
Copper Cabling Identify the basic characteristics of copper cabling.
UTP Cabling Explain how UTP cable is used in Ethernet networks.
Fiber-Optic Cabling Describe fiber optic cabling and its main advantages
over other media.
Wireless Media Connect devices using wired and wireless media.

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

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Purpose of the Physical Layer
The Physical Connection
• Before any network communications can occur, a physical connection to a local
network must be established.
• This connection could be wired or wireless, depending on the setup of the network.
• This generally applies whether you are considering a corporate office or a home.
• A Network Interface Card (NIC) connects a device to the network.
• Some devices may have just one NIC, while others may have multiple NICs (Wired
and/or Wireless, for example).
• Not all physical connections offer the same level of performance.

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Purpose of the Physical Layer
The Physical Layer
• Transports bits across the
network media
• Accepts a complete frame from
the Data Link Layer and
encodes it as a series of
signals that are transmitted to
the local media
• This is the last step in the
encapsulation process.
• The next device in the path to
the destination receives the bits
and re-encapsulates the frame,
then decides what to do with it.

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4.2 Physical Layer
Characteristics

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Physical Layer Characteristics
Physical Layer Standards

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Physical Components
Physical Layer Standards address three functional areas:
• Physical Components
• Encoding
• Signaling
The Physical Components are the hardware devices, media, and other
connectors that transmit the signals that represent the bits.
• Hardware components like NICs, interfaces and connectors, cable materials, and cable designs
are all specified in standards associated with the physical layer.

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Encoding
• Encoding converts the stream of
bits into a format recognizable by
the next device in the network
path.
• This ‘coding’ provides predictable
patterns that can be recognized by
the next device.
• Examples of encoding methods
include Manchester (shown in the
figure), 4B/5B, and 8B/10B.

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Signaling
• The signaling method is how the bit
values, “1” and “0” are represented on
the physical medium.
• The method of signaling will vary based
on the type of medium being used.
Electrical Signals Over Copper Cable
Light Pulses Over Fiber-Optic Cable
Microwave Signals Over Wireless

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Bandwidth
• Bandwidth is the capacity at which a medium can carry data.
• Digital bandwidth measures the amount of data that can flow from one place to
another in a given amount of time; how many bits can be transmitted in a second.
• Physical media properties, current technologies, and the laws of physics play a role
in determining available bandwidth.
Unit of Bandwidth Abbreviation Equivalence
Bits per second bps 1 bps = fundamental unit of bandwidth
Kilobits per second Kbps 1 Kbps = 1,000 bps = 103 bps
Megabits per second Mbps 1 Mbps = 1,000,000 bps = 106 bps
Gigabits per second Gbps 1 Gbps – 1,000,000,000 bps = 109 bps
Terabits per second Tbps 1 Tbps = 1,000,000,000,000 bps = 1012 bps

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Bandwidth Terminology
Latency
• Amount of time, including delays, for data to travel from one given point to another
Throughput
• The measure of the transfer of bits across the media over a given period of time
Goodput
• The measure of usable data transferred over a given period of time
• Goodput = Throughput - traffic overhead

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4.3 Copper Cabling

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Copper Cabling
Characteristics of Copper Cabling
Copper cabling is the most common type of cabling used in networks today. It is
inexpensive, easy to install, and has low resistance to electrical current flow.
Limitations:
• Attenuation – the longer the electrical signals have to travel, the weaker they get.
• The electrical signal is susceptible to interference from two sources, which can distort and corrupt
the data signals (Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI) and
Crosstalk).
Mitigation:
• Strict adherence to cable length limits will mitigate attenuation.
• Some kinds of copper cable mitigate EMI and RFI by using metallic shielding and grounding.
• Some kinds of copper cable mitigate crosstalk by twisting opposing circuit pair wires together.

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Copper Cabling
Types of Copper Cabling

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Copper Cabling
Unshielded Twisted Pair (UTP)
• UTP is the most common networking
media.
• Terminated with RJ-45 connectors
• Interconnects hosts with intermediary
network devices.
Key Characteristics of UTP
1. The outer jacket protects the copper
wires from physical damage.
2. Twisted pairs protect the signal from
interference.
3. Color-coded plastic insulation
electrically isolates the wires from
each other and identifies each pair.

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Copper Cabling
Shielded Twisted Pair (STP) • Better noise protection than UTP
• More expensive than UTP
• Harder to install than UTP
• Terminated with RJ-45 connectors
• Interconnects hosts with intermediary
network devices
Key Characteristics of STP
1. The outer jacket protects the copper
wires from physical damage
2. Braided or foil shield provides
EMI/RFI protection
3. Foil shield for each pair of wires
provides EMI/RFI protection
4. Color-coded plastic insulation
electrically isolates the wires from
each other and identifies each pair

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Copper Cabling
Coaxial Cable
Consists of the following:
1. Outer cable jacket to prevent minor physical
damage
2. A woven copper braid, or metallic foil, acts as the
second wire in the circuit and as a shield for the
inner conductor.
3. A layer of flexible plastic insulation
4. A copper conductor is used to transmit the
electronic signals.
There are different types of connectors used with coax
cable.
Commonly used in the following situations:
• Wireless installations - attach antennas to wireless
devices
• Cable internet installations - customer premises
wiring

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4.4 UTP Cabling

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UTP Cabling
Properties of UTP Cabling
UTP has four pairs of color-coded copper wires
twisted together and encased in a flexible plastic
sheath. No shielding is used. UTP relies on the
following properties to limit crosstalk:
• Cancellation - Each wire in a pair of wires uses
opposite polarity. One wire is negative, the other
wire is positive. They are twisted together and the
magnetic fields effectively cancel each other and
outside EMI/RFI.
• Variation in twists per foot in each wire - Each wire
is twisted a different amount, which helps prevent
crosstalk amongst the wires in the cable.

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UTP Cabling
UTP Cabling Standards and Connectors
Standards for UTP are established by the TIA/EIA. TIA/EIA-
568 standardizes elements like:
• Cable Types
• Cable Lengths
• Connectors
• Cable Termination
• Testing Methods
Electrical standards for copper cabling are established by the
IEEE, which rates cable according to its performance.
Examples include:
• Category 3
• Category 5 and 5e
• Category 6

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UTP Cabling
UTP Cabling Standards and Connectors (Cont.)
RJ-45 Connector
RJ-45 Socket
Poorly terminated UTP cable
Properly terminated UTP cable

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UTP Cabling
Straight-through and Crossover UTP Cables
Cable Type Standard Application
Ethernet Straight-through Both ends T568A or T568B Host to Network Device
Ethernet Crossover * One end T568A, other end
T568B
Host-to-Host, Switch-to-Switch,
Router-to-Router
* Considered Legacy due to most NICs using Auto-MDIX to sense cable type and complete connection
Rollover Cisco Proprietary Host serial port to Router or Switch
Console Port, using an adapter

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4.5 Fiber-Optic Cabling

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Fiber-Optic Cabling
Properties of Fiber-Optic Cabling
• Not as common as UTP because of the expense involved
• Ideal for some networking scenarios
• Transmits data over longer distances at higher bandwidth than any other
networking media
• Less susceptible to attenuation, and completely immune to EMI/RFI
• Made of flexible, extremely thin strands of very pure glass
• Uses a laser or LED to encode bits as pulses of light
• The fiber-optic cable acts as a wave guide to transmit light between the two
ends with minimal signal loss

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Fiber-Optic Cabling
Types of Fiber Media
Single-Mode Fiber
• Very small core
• Uses expensive lasers
• Long-distance applications
Multimode Fiber
• Larger core
• Uses less expensive LEDs
• LEDs transmit at different angles
• Up to 10 Gbps over 550 meters
Dispersion refers to the spreading out of a light pulse over time. Increased dispersion means
increased loss of signal strength. MMF has greater dispersion than SMF, with a the maximum cable
distance for MMF is 550 meters.

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Fiber-Optic Cabling
Fiber-Optic Cabling Usage
Fiber-optic cabling is now being used in four types of industry:
1. Enterprise Networks - Used for backbone cabling applications and interconnecting
infrastructure devices
2. Fiber-to-the-Home (FTTH) - Used to provide always-on broadband services to
homes and small businesses
3. Long-Haul Networks - Used by service providers to connect countries and cities
4. Submarine Cable Networks - Used to provide reliable high-speed, high-capacity
solutions capable of surviving in harsh undersea environments at up to transoceanic
distances.
Our focus in this course is the use of fiber within the enterprise.

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Fiber-Optic Cabling
Fiber-Optic Connectors
Straight-Tip (ST) Connectors
Subscriber Connector (SC) Connectors
Lucent Connector (LC) Simplex Connectors
Duplex Multimode LC Connectors

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Fiber-Optic Cabling
Fiber Patch Cords
SC-SC MM Patch Cord LC-LC SM Patch Cord ST-LC MM Patch Cord ST-SC SM Patch Cord
A yellow jacket is for single-mode fiber cables and orange (or aqua) for multimode fiber
cables.

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Fiber-Optic Cabling
Fiber versus Copper
Optical fiber is primarily used as backbone cabling for high-traffic, point-to-point
connections between data distribution facilities and for the interconnection of buildings
in multi-building campuses.
Implementation Issues UTP Cabling Fiber-Optic Cabling
Bandwidth supported 10 Mb/s - 10 Gb/s 10 Mb/s - 100 Gb/s
Distance Relatively short (1 - 100 meters) Relatively long ( 1 - 100,000 meters)
Immunity to EMI and RFI Low High (Completely immune)
Immunity to electrical hazards Low High (Completely immune)
Media and connector costs Lowest Highest
Installation skills required Lowest Highest
Safety precautions Lowest Highest

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4.6 Wireless Media

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Wireless Media
Properties of Wireless Media
It carries electromagnetic signals representing binary digits using radio or
microwave frequencies. This provides the greatest mobility option. Wireless
connection numbers continue to increase.
Some of the limitations of wireless:
• Coverage area - Effective coverage can be significantly impacted by the physical
characteristics of the deployment location.
• Interference - Wireless is susceptible to interference and can be disrupted by many
common devices.
• Security - Wireless communication coverage requires no access to a physical strand
of media, so anyone can gain access to the transmission.
• Shared medium - WLANs operate in half-duplex, which means only one device can
send or receive at a time. Many users accessing the WLAN simultaneously results in
reduced bandwidth for each user.

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Wireless Media
Types of Wireless Media
The IEEE and telecommunications industry standards for wireless data communications
cover both the data link and physical layers. In each of these standards, physical layer
specifications dictate:
• Data to radio signal encoding methods
• Frequency and power of transmission
• Signal reception and decoding requirements
• Antenna design and construction
Wireless Standards:
• Wi-Fi (IEEE 802.11) - Wireless LAN (WLAN) technology
• Bluetooth (IEEE 802.15) - Wireless Personal Area network (WPAN) standard
• WiMAX (IEEE 802.16) - Uses a point-to-multipoint topology to provide broadband wireless
access
• Zigbee (IEEE 802.15.4) - Low data-rate, low power-consumption communications, primarily
for Internet of Things (IoT) applications

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Wireless Media
Wireless LAN
In general, a Wireless LAN (WLAN) requires the following devices:
• Wireless Access Point (AP) - Concentrate wireless signals from users and
connect to the existing copper-based network infrastructure
• Wireless NIC Adapters - Provide wireless communications capability to
network hosts
There are a number of WLAN standards. When purchasing WLAN equipment,
ensure compatibility, and interoperability.
Network Administrators must develop and apply stringent security policies and
processes to protect WLANs from unauthorized access and damage.

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Wireless Media
Packet Tracer – Connect a Wired and Wireless LAN
In this Packet Tracer, you will do the following:
• Connect to the Cloud
• Connect a Router
• Connect Remaining Devices
• Verify Connections
• Examine the Physical Topology

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Wireless Media
Lab – View Wired and Wireless NIC Information
In this lab, you will complete the following objectives:
• Identify and Work with PC NICs
• Identify and Use the System Tray Network Icons

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4.7 Module Practice and Quiz

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Module Practice and Quiz
Packet Tracer – Physical Layer Exploration– Physical Mode
In this Packet Tracer Physical Mode (PTPM) activity, you will complete the following:
 Examine Local IP Addressing Information
 Trace the Path Between Source and Destination

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Packet Tracer – Connect the Physical Layer
In this Packet Tracer, you will do the following:
• Identify Physical Characteristics of Internetworking Devices
• Select Correct Modules for Connectivity
• Connect Devices
• Check Connectivity

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What did I learn in this module?
• Before any network communications can occur, a physical connection to a local network,
either wired or wireless, must be established.
• The physical layer consists of electronic circuitry, media, and connectors developed by
engineers.
• The physical layer standards address three functional areas: physical components,
encoding, and signaling.
• Three types of copper cabling are: UTP, STP, and coaxial cable (coax).
• UTP cabling conforms to the standards established jointly by the TIA/EIA. The electrical
characteristics of copper cabling are defined by the Institute of Electrical and Electronics
Engineers (IEEE).
• The main cable types that are obtained by using specific wiring conventions are Ethernet
Straight-through and Ethernet Crossover.

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What did I learn in this module (Cont.)?
• Optical fiber cable transmits data over longer distances and at higher bandwidths than any
other networking media.
• There are four types of fiber-optic connectors: ST, SC, LC, and duplex multimode LC.
• Fiber-optic patch cords include SC-SC multimode, LC-LC single-mode, ST-LC multimode,
and SC-ST single-mode.
• Wireless media carry electromagnetic signals that represent the binary digits of data
communications using radio or microwave frequencies. Wireless does have some limitations,
including coverage area, interference, security, and the problems that occur with any shared
medium.
• Wireless standards include the following: Wi-Fi (IEEE 802.11), Bluetooth (IEEE 802.15),
WiMAX (IEEE 802.16), and Zigbee (IEEE 802.15.4).
• Wireless LAN (WLAN) requires a wireless AP and wireless NIC adapters.

Modulo 4 cisco ccna v7 para estudiantes d

Modulo 4 cisco ccna v7 para estudiantes d

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