chapter 3 vn.2
TRANSCRIPT
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Chapter 3 11
Transmission Media
Chapter 3
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Chapter 3 2
Chapter Objectives
Discuss characteristics of cables
List the various types of copper wired cables
Discuss fiber optic cables
List the various types of wireless transmission media
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Chapter 3 3
Recall - I
Topology is a pattern of computer devices anddescribes the way in which these devices are
connected
The disadvantages of bus topology are:
Entire network gets affected if main cable breaks
Terminators are required at both ends of backbone
cable
Difficult to detect the faulty device Limited number of devices can be attached
Heavy traffic degrades performance
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Chapter 3 4
Recall - II
The advantages of ring topology are:
Easier to mange as compared to Bus network
Handles large volume of traffic
Very reliable and offers great speed
Provides a good communication over a long distance
No terminators are required
Types of mesh topology are:
Full mesh topology Partial mesh topology
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Chapter 3 5
Characteristics of Cables
Segment Length
Length of single wire Attenuation Indicates loss of signal
Bandwidth Amount of data carried by cable
Number of Segments Maximum number of
segments in network
Cost Copper cables are cheapest, fiber optic
cables are expensive
Interference susceptibility and crosstalk
Definesconcept of electronic interference on cables
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Chapter 3 6
Types of cables
Copper medium is the cheapest mode of data transfer
Types of cables
Coaxial cable Twisted pair cables
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Coaxial cable
Consist of a solid copper core surrounded by aninsulator mainly made up of Poly Vinyl Chloride(PVC) or Teflon
Coaxial cables are less prone to interference (bothinternal and external)
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Chapter 3 8
Types of Coaxial cable
Coaxial cables are mainly divided into fourcategories
Types of
Coaxial cables
RG58 RG8 RG6 RG59
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Chapter 3 9
RG58
Maximum segment length is 200 meters
Interference protection is better than twisted pair
cables
Offers resistance of 50 ohms BNC-T connector is used to connect this cable
Used in thinnet (10BASE2) network
Mostly used in changing environments
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Chapter 3 10
RG8
Maximum segment length is 500 meters
Interference protection is good compared to any
copper cable
Offers resistance of 50 ohms BNC-T or Vampire Tap connector is used to connect
this cable
Used in 10BASE5 network
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Chapter 3 11
RG6
Broadband quad-shielded
cable that offers an
impedance of 75 ohms
Provides lower attenuationcharacteristics
Useful in cable TV, CCTV
and satellite dish antenna
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Chapter 3 12
RG59
Solid conductor is
surrounded by a foam
polyethylene dielectric
Offers impedance of 75ohm
Useful in security
camera, cable TV and
home theatre
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Chapter 3 13
Twisted Pair Cables
A pair of cables twisted around each other forms a twistedpair cable.
Twisted Pair cables
UnshieldedTwisted Pair
ShieldedTwisted pair
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Chapter 3 14
UTP Cables
Pair of unshielded wires
wound around each other
Easily gets affected by
EMI, RFI and crosstalk Cable offers resistance of
50 ohms
Maximum segment length
is 100 meters
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Chapter 3 15
UTP Cable Types
Cat 7
Cat 6
Cat 5eCat 5
Cat 4
Cat 3
Cat 2
Cat 1
UTP
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STP Cables
Pair of wires wound
around each other is
placed inside shield
Better protection fromEMI, RFI and crosstalk
as compared to UTP
Offers resistance of 50
ohms Maximum segment
length of 100 meters
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Chapter 3 17
Case Study 1
The Mumbai branch of MoneyMaker bank has
multiple departments, which are on different floors in
the same building. Each department is
interconnected using UTP cables. John, the networkadministrator has set up a client server environment
and has used a star topology. The employees of the
bank are unable to transmit data and information
from one department to another in an efficientmanner
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Problem
Data and information cannot be transmitted betweenthe departments efficiently
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Suggested Solution
The problem is caused due to EMI emitted by the
electrical transformers. John should use STP cables
to interconnect the different departments located oneach floor as STP provides better protection from
EMI. The computers inside each department can be
interconnected using UTP cables.
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Chapter 3 20
Fiber Optic Medium
Consists of centre glass core surrounded by cladding Electrical signals are converted into light signals
A phenomenon called as total internal reflection is
used for transmission
LED or laser is used to transmit signal
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Fiber Optic Cable Characteristics
Bandwidth Carries large amount of data ranging
from 100 Mbps to 1 Gbps
Segment Length Transmits data signals over
larger distance Interference No electric signals pass through
these types of cables thus providing security
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Fiber Optic Cable Types
Fiber optic cables can carry signals in a singledirection.
Fiber Optic Cable
Types
Single Mode Multi mode
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Single Mode Fiber Optic cable
A type of cable that has only a single strandof glass fiber with a thin diameter.
Fiber optic cables that use lasers are knownas single mode cable.
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Multi Mode Fiber Optic cable
A type of cable that contains a glass fiber with alarger diameter.
It is a 62.5/125 micrometer fiber cable.
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Fiber Optic Cable Connectors
Straight Tip (ST) Joins individual fibers to optical
devices
Subscriber Connector (SC) Attaches two fibers to
send and receive signals Medium Interface Connector (MIC) Joins fiber to
FDDI controller
Sub Miniature Type A (SMA) Uses individual
connectors for each fiber stand Fiber Jack Attaches two fibers in snap lock
connector
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Chapter 3 26
Case Study 2
The Chennai branch of MoneyMaker bank has a
database server. All departments are connected to
this server using coaxial cables. These departmentsare unable to retrieve and update information from
the server spontaneously. It takes a lot of time to get
updated information.
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Problem
The employees of the bank are unable to retrieve
information from the database quickly.
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Suggested Solution
The problem is caused due to the lower transmissionspeeds provided by the coaxial cables. These cables
provide a maximum transfer rate of 10 Mbps. Thus, if
all departments of the bank try to access the
information from the server, the speed slows down.To increase the data transfer rate, the network
administrator should use UTP Cat 6 twisted pair
cables. This cable provides higher bandwidth and
higher data transfer rate as compared to coaxialcables.
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Chapter 3 29
Wireless Medium
Unguided form of transmission medium
Transmitters and receivers are used to send and
receive signals
Involves use of electromagnetic waves such asmicrowave, infrared, radio waves etc.
Wireless medium is useful in connecting large
geographical areas
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Radio Waves
Line of sight between devices is not required
Frequencies used are VLF, LF, MF, HF, VHF, UHF,
SHF and EHF
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Microwave
High frequency EM wave that is used for point to point
communication
Microwave Categories:
Terrestrial
Relay towers are used to transmitradio signals between earth stations
Satellite Radio signals are transmitted between
different base stations using satellites
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Infrared Transmission
Uses Infrared lights for transmission and receptionof signals
Line of sight must be maintained between the
devices
Mainly used in LAN environments
LEDs or Injection Laser Diode (ILD) is used to
transmit information and photodiodes are used to
receive the signals
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Chapter 3 33
Case Study - 3
Money Maker Bank plans to link all its branches
located across India to a centralized server
located in Mumbai. As all the branches are
located at various geographical locations, thebank plans to maintain an account of all the
transactions of each and every branch. The
overhead cost of the current network is too
high. So the network administrator wants to use
a cost effective way.
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Problem
Identify the type of setup required to connect
various branches to the central server in a costeffective manner.
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Suggested Solution
The bank should establish a wireless network
from all the branches to the central server. This
will reduce the cost of installing cables for
interconnecting the branches. This will alsoreduce the overhead cost of maintenance of
cables, as it is costlier to connect all the
branches, which are spread in India, using
cables.
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Chapter 3 36
Media Comparison
Characteristics UTP STP Coaxial Cables Fiber Optic Cables
Bandwidth 10 Mbps100 Mbps 10 Mbps100 Mbps 10 Mbps 100 Mbps - 1 Gbps
Maximum cable segment 100 meters 100 meters 200500 meters 2 k.m.100 k.m.
Interference rating Poor Better than UTP Better than twisted pairwires
Very good as comparedto any other cable
Installation cost Cheap Costly than UTP Costly than twisted pair
wires
Most costly to install
Bend radius 360 degrees / feet 360 degrees / feet 360 degrees / feet or 30
degrees / feet
30 degrees / feet
Security Low Low Low High
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Chapter 3 37
SummaryI
Networking hardware involves all peripheral devices,interface cards and other components such as cablesand wires that are used to establish network connection
All cables have certain characteristics such as segmentlength, bandwidth, crosstalk, attenuation, interferencesusceptibility, cost and number of segments
Different types of medium are available for transmittingdata over the network such as copper medium, fiber
optic medium and wireless medium Copper medium includes coaxial cables and twisted pair
cables
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SummaryII
Twisted pair cable consists of a pair of cables that is
twisted around each other
Two types twisted pair cable are STP and UTP
Crosstalk is a phenomenon in which signals of one wireinterfere with the signals transmitted over the other wire
To avoid crosstalk, a pair of wires wound around each
other and each pair is placed inside a protective foil wrap
Types of UTP cables are Cat 1, Cat 2, Cat 3, Cat 4, Cat5, Cat 5e, Cat 6 and Cat 7
STP cable types include Cat 5e and 150 ohm shielded
cable
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SummaryIII
Coaxial cables consist of a solid copper core that issurrounded by an insulator which is again covered by amesh like ground wire and an outer cover known as asheath
Thinwire or RG-58 cable is approximately 0.64 cm indiameter and is used in constantly changingenvironments
BNC connector is used to connect devices to the thinnet
coaxial cable network RG-8 cable is approximately 1 cm in diameter and used
as a backbone cable
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SummaryIV
For RG-6 cable, the center conductor is 1.05 mm in
diameter and for RG-59 cable is 0.86 mm
A fiber optic cable consists of a centre glass core that is
surrounded by a glass cladding, Kevlar fibers and anouter sheath material
LEDs and lasers are used to transmit light signals
through the fiber optic cables
There are two types of fiber optic cables availablenamely single mode and multi mode
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SummaryV
The primary types of connectors used to connect fiber
cables are ST, SC, SMA, Fiber Jack and MIC
In wireless medium, signals are transmitted through air
and space using radio and satellite networks High frequency radio waves used for point to point
communication of audio, data and video signals are
called as microwaves
Infrared wireless transmission networks use Infraredlights to send and receive signals