LECTURE 5 NETWORK MEDIA AND DATA TRANSMISSION

Question 1

What are the different types of connection

Answer 1

A physical connection
can be a wired
connection using a
cable or a wireless
connection using
radio waves.

Question 2

What is an NIC?

Answer 2

It is a circuit board installed in a computer that provides a dedicated network connection to the
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

Question 3

What is the role of the physical layer?

Answer 3

• 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.

Question 4

Give the three basic forms of network media together with the various forms of signals they use

Answer 4

Copper cable- Electrical signals
Light pulse- Fiber optic cable
Wireless- Microwave signals

Question 5

Give examples of physical layer standards

Answer 5

 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)

Question 6

What are the functions of the physical layer?

Answer 6

1.Encoding- Method of converting a stream of data bits into predefined code
2.Signlaing method
Method of representing the bits. Physical layer standards must define what type of signal
represents a “1” and what type of signal represents a “0”.

Question 7

What is modulation

Answer 7

The process by which the characteristic of one wave(the signal) modifies another wave (the carrier)

Question 8

Describe bandwidth

Answer 8

 Capacity of a medium to carry data.
 Digital bandwidth measures the amount of data that can flow from one place to another in a given amount of time.
 Bandwidth is sometimes thought of as the speed that bits travel, however this is not accurate. In
both 10Mb/s and 100Mb/s Ethernet, the bits are sent at the speed of electricity. The difference is the number of bits that are transmitted per second.

Question 9

What is throughput and goodput

Answer 9

Measure of the transfer of bits across the media over a given period of time.

 Goodput is throughput minus traffic overhead for establishing sessions,
acknowledgments, and encapsulation.

Question 10

Why doesn’t throughput usually match the specified bandwidth in the physical layer

Answer 10

• Amount of traffic
• Type of traffic
• Latency created by network devices
encountered between source and destination

Question 11

What are the characteristics of copper media?

Answer 11

 Transmitted on copper cables as electrical pulses.
 Attenuation - the longer the signal travels, the more
it deteriorates.
 All copper media must follow strict distance
limitations.
 Electromagnetic interference (EMI) or radio
frequency interference (RFI) - distorts and corrupts
the data signals being carried by copper media. (To counter copper cables wrapped in shielding.)
 Crosstalk - disturbance caused by the electric or
magnetic fields of a signal on one wire to the signal
in an adjacent wire.
(To cancel crosstalk opposing circuit wire pairs
twisted together.)

Question 12

What are the three main types of copper media used in networking

Answer 12

Unshielded Twisted Pair (most common)
Shielded twisted Pair cable
Coaxial cable

Question 13

What are the properties of the UTP?

Answer 13

• Terminated with RJ-45 connectors.
• Used for interconnecting network hosts with networking devices such as switches.
• Consists of four pairs of color-coded wires that have been twisted together to help protect against signal
interference from other wires.
• Color codes aid in cable termination.
• Small size can be advantageous during
installation.
• UTP cable does not use shielding to counter
the effects of EMI and RFI.

Question 14

What are the parts of a UTP cable?

Answer 14

Outer Jacket- Protects the copper wire from physical damage
Twisted-Pair -Protects the signal from interference
Color-coded plastic insulation- Electrically isolates wires form each other and identifies each pair

Question 15

What is cancellation in UTPs?

Answer 15

Cancellation: When two wires in an electrical
circuit are placed close together, their magnetic
fields are the exact opposite of each other and cancel out any outside EMI and RFI signals.
• Varies the number of twists per wire pair to
further enhance the cancellation effect of a
paired circuit.

Question 16

What are the different UTP Cabling standards

Answer 16

Cat 3- Voice
Cat 5 and 5e (ethernet) - data
Cat 6- data

Question 17

What are the UTP Connectors?

Answer 17

RJ-45- (male component)

socket(female component)

Question 18

What are the types of UTP cables

Answer 18

Straight- through-
2 different types of devices
same standards at both ends
Cross-over-
similar devices. Different standards at their ends
Rollover-(cisco proprietary) Connects a workstation serial port to a router console port, using an adapter

Question 19

What are the UTP testing parameters?

Answer 19

 Wire map
 Cable length
 Signal loss due to attenuation
 Crosstalk

Question 20

What are the properties of an STP cable?

Answer 20

 STP provides better noise protection than UTP.
 STP cable is significantly more expensive and difficult to install.
 Uses an RJ-45 connector.
 Combines the techniques of shielding to counter EMI and RFI, and wire twisting to counter crosstalk.
 Uses four pairs of wires, each wrapped in a foil shield, which are then wrapped in an overall metallic braid or foil.

Question 21

What are parts of an STP cable?

Answer 21

Outer jacket
Overall braided or foil shield
Foil shield wrapped around each pair of wire

Question 22

What are the parts of a coaxial cable?

Answer 22

• A copper conductor used to transmit the electronic signals.
• A layer of flexible plastic insulation surrounding a copper conductor.
• The insulating material is surrounded in a woven copper braid, or metallic foil, that acts as the second wire in the circuit and as a shield for the inner conductor.
• The entire cable is covered with a cable jacket to prevent minor physical damage.

Question 23

Where is the coaxial cable used?

Answer 23

Wireless installations: Coaxial cables attach antennas to wireless devices.
• Cable Internet installations

Question 24

What are some practices for copper media safety?

Answer 24

Copper media are susceptible to fire and electrical hazards so:

i) The separation of data and electrical power cabling must comply with safety codes
ii) Cables must be connected correctly
iii) Installations must be inspected for damage
iv) Equipment must be grounded correctly

Question 25

What are the properties of fiber optic cabling?

Answer 25

 Transmits data over longer distances and at
higher bandwidths.
 Transmit signals with less attenuation and is
completely immune to EMI and RFI.
 Used to interconnect network devices.
 Flexible, but extremely thin, transparent strand
of very pure glass, not much bigger than a
human hair.
 Bits are encoded on the fiber as light pulses

Question 26

In what type of industries is fiber-optic cabling being used?

Answer 26

 Enterprise Networks
• Fiber-to-the-Home (FTTH)
• Long-Haul Networks
• Submarine Cable Networks

Question 27

What are the parts of the fiber optic cable

Answer 27

1.Jacket
Protects the fiber against abrasion, moisture, and other contaminants. Composition can vary depending on the
cable usage.

2.Strengthening Material
Surrounds the buffer, prevents the fiber cable from being stretched when it is being pulled. Often the same material used to produce bulletproof vests.

3.Buffer
Used to help shield the core and cladding from damage.

4.Cladding
Tends to act like a mirror by reflecting light back in the
core of the fiber. Keeps light in the core as it travels
down the fiber.

5.Core
Light transmission element at the center of the optical
fiber. Core is typically silica or glass. Light pulses travel
through the fiber core.

Question 28

What are the two types of fiber media

Answer 28

Single mode
small core
less dispersion
Suited for long distance applications