OSI Physical Layer Flashcards
1
Q
It provides the means to transport across the network media the bits that make up a Data Link layer frame
A
Physical Layer
2
Q
The delivery of frames across the local media requires the following physical layer elements
A
- Physical Media and Connectors
- Reprsentation of Bits on the Media
- Encoding of Data and Control Information
- Transmitter and Receiver circuitry on the network devices
3
Q
The Purpose of the Physical Layer
A
- Create the electrical, optical or microwave signals that represents the bits in each frame
- retrieve the individual signals from the media, restore them to their bit representations and pass the bits up to the Data Link Layer as a complete frame
4
Q
The Three Basic Forms of Network Media on which Data is Represented:
A
Copper
Fiber
Wireless
5
Q
It is a basic form of network media on which data is represented in patterns of electrical pulses
A
Copper
6
Q
It is a basic form of network media on which data is represented in patterns of light pulses
A
Fiber
7
Q
It is a basic form of network media on which data is represented in patterns of radio transmissions
A
Wireless
8
Q
It is the organization that defines the standards in the TCP/IP suite
A
Internet Engineering Task Force (IETF)
9
Q
ISO
A
International Organization for Standardization
10
Q
IEEE
A
International Electronics and Electrical Engineers
11
Q
ANSI
A
American National Standards Institute
12
Q
ITU
A
International Telecommunication Union
13
Q
EIA
A
Electronics Industry Alliance
14
Q
TIA
A
Telecommunications Industry Assoociation
15
Q
FCC
A
Federal Communication Commission
16
Q
CRTC
A
Canadian Radion and TV Commission
17
Q
Four Areas that are being standardized by the different Standardizing Organizations for the Physical Layer
A
- Physical and Electrical properties of the media
- Mechanical Properties of the connectors
- Bit representation by the signals
- Definition of Control Information Signals
18
Q
Three Fundamental Functions of the Physical Layer
A
- The Physical Components
- Data Encoding
- Signaling
19
Q
It is a fundamental function of the Physical Layer that concerns the electronic hardware devices and the media and connectors that transmit and carry signls to represent the bits
A
The Physical Components
20
Q
- It is the method of converting a stream of data bits used to provide a predictable pattern that can be recongnized by both the sender and the receiver
- Also identifies the beginning and end of a frame
A
Data Encoding
21
Q
It involves the determining how to represent the binary bit on a specific medium
A
Signaling
22
Q
It refers to the specific amount og time to occupy the media
A
Bit Time
23
Q
Ways to Represent a Signal on the Medium
A
- Varying Amplitude
- Varying Frequency
- Varying Phase
-Clock
24
Q
Nonreturn to Zero Signaling Method
A
0 is repressented by one voltage level and 1 is represented with a dfferent voltage level
25
Manchester Encoding
0 is represented from a high to love voltage transition in the middle of the bit time. 1 is represented from a low to high voltage transition
26
NRZ
Nonreturn to Zero
27
When is it suited to use NRZ Signaling Method
Suited for slow speed data links
28
Where does Manchester Encoding usually implemented?
10BaseT Ethernet
29
Grouping Bits
It represents the symbolic grouping of bits prior to it being presented to the media
30
It is a consecutive Sequence of Code bits that are interpreted and mapped as data bit patterns
Code Group
31
It is a symbol that is a predefined small group of bits that represents a larger group of data bits
Code Group
32
It is the bit patterns used in encoding techniques
Symbol
33
Pros of Code Groups
- Reduces Bit Level Error
- Limits the effective energy transmitted into the media
- Helps distinguish data bits from control bits
- Provides better media error detection
34
These refer to symbols being sent down from the Physical Layer
Data Symbols
35
These are symbols of Layer 1 pattenrs denoting the beginning and end of frames
Control Symbols
36
These are symbols that refer to bit patterns that are not allowed on the media that can indicate error
Invalid Symmbols
37
4B/5B Technique
4 bits of data are turned into 5-bit code symbols for transmission over the media system.
Each byte to be transmitted is broken into four-bit pieces or nibbles and encoded as five-bit values as symbols.
Among the symbols are coees that indicate the beginning and end of the frame transmission
38
Three Measurements of Data Transfer
Bandwidth
Throughput
Goodput
39
It refers to the amount of information that can flow from one place to another in a given amount of time
Bandwidth
40
It refers to the measure of the transfer of bits across the media over a given period of time
Throughput
41
It refers to the measure of usable data transferred over a givem period of time
Goodput
42
Factors affecting bandwidth
- properties of the physical media
- technologies chosen for signaling and detecting network signals
- laws of physics
43
factors that influence throughput
- amount of traffic
- type of traffic
- the number of network devices encountered on the network being measured
44
Most commonly used media for data communications
Copper Wires
45
Standards for Copper media are defined for the:
- type of cabing used
- bandiwidth of the communication
- type of connectors used
- pinout and color codes of connections to the media
- maximum distance of the media
46
It refers to interference caused by the magnetic field around adjacent pairs of wires in the cable
Crosstalk
47
It is a type of copper media that is common, cheap and easy to install that consists of 4 pairs of color-coded wires that have been twisted together
UTP (Unshielded Twisted Pair)
48
It refers to the canceling out of the effects of crosstalk between the 2 twisted wires and between wire pairs
Cancellation
49
It is a cable type that both end on t568A or t568b
Ethernet Straight-Through
50
It is a type of cable wherein one end is t568a and the other is t568b
Ethernet Crossover
51
It is a type of cable that is cisco proprietary
Rollover
52
When do you use straight through cabling
- Connecting a network host to a network device
53
When do you use crossover
Connecting two network hosts
conneccting two network intermediary devices
54
This type of copper media uses two pairs of wires that are wrapped in an overall metallic braid or foil
STP (Shielded Twisted Pair)
55
It is a type of Copper media wherein it consists of a copper conductor surrounded by a layer of flexible insulation
Coaxial Cable
56
It is a type of Coaxial Cable where it incorporates optic fibers along the cable to create broadband networks
Hybrid Fiber Coax
57
Safety Hazards with Copper Media
- copper media has wires that could conduct electricity in undesirable ways
- copper cabling may conduct voltages caused by lightning strikes
- cabling insulation sheaths may be flammable or produce toxic fumes when burned
58
It is a type of media wherein it uses either glass or plastic fibers to guide light impulses from source to destination
Fiber Media
59
Two types of Fiber Media
- Single Mode
- Multimode
60
it is a type of fiber media where in there is a small core, less despersion and is suited for long distance applications that uses lasers as the light source
Single Mode
61
It is a type of fiber media that has laeger core, allows greater dispersion; can be used for long distance but its shorter than single-mode and uses LEDs as the light source
Multimode
62
This type of media uses radio waved to carry signals
Wireless Media
63
It is a type of Wireless network commonly referred to as Wi-Fi that uses contention or non-deterministic system with a CSMA/CA media access process
Standard IEEE 802.11
64
It is a wireless Personal Area Network (WPAN) commonly known as Bluetooth, uses a device pairing process to communicate with devices over distances from 1 to 100 meters
Standard IEEE 802.15
65
It is commonly known as Worldwide Interoperability for Microwave Access (WiMAX), uses a point-to-multipoint topology to provide wireless broadband access
Standard IEEE 802.16
66
It includes physical layer specifications that enable the implementation of Layer 2 General Packet Radio Service (GPRS) protocol to provide data transfer over mobile cellular telephony networks
Global System for Mobile Communications (GSM)
67
What is Wi-Fi?
Wireless Fidelity
68
What is WPAN
Wireless Personal Area Network
69
WiMAX
Worldwide Interoperability for Microwave Access
70
What is GSM?
Global System for Mobile Communications
71
What is GPRS
General Packet Radio Service
72
Requirements for a Wireless LAN
- Wireless Access Point (AP
- Wireless NIC Adapter
73
It is one of the requirements for WLAN that concentrates the wireless signals from users and connects, usually through a copper cable, to the existing copper-based network infrastrutre such as Ethernet
Wireless Access Point
74
It is one of the requirements of a WLAN that provides wireless communication capability to each network host
Wireless NIC Adapter
75
This IEEE Standard operates in the 5GHz frequency badn with speeds of up to 54 Mbps, has small coverage
IEEE 802.11a
76
This IEEE Standard operates in the 2.4 GHz frequency band with speeds up to 11 Mbps and has longer range tahtn devices based on 802.11a
IEEE 802.11b
77
This IEEE standard operates in the 2.4 GHz frequency band width speeds of up to 54 Mbps. It has the same frequency as 802.11b but with the bandwidth of 802.11a
IEEE 802.11g
78
This is an IEEE standard that is currently in draft form that is proposed to operate in the 2.4 GHz or 5 GHz with expected data rates of 100 Mbps to 210 Mbps witha distance range of up to 70 Meters
IEEE 802.11n
79
Copper Media Connectors
110 Punch Block
RJ45 UTP Plug
RJ45 UTP Socket
80
Media Connectors for Fiber Optics
Straight-Tip (ST)
Subscriber Connector (SC)
Lucent Connector (LC)
81
It is a type of Fiber Optic Connector that is trademarked by AT&T that is a very common bayonet style connector widely used with multimode fiber
Straight-Tip
82
It is a connector that uses a push-pull mechanism to ensure positive insertion that is widely used with single-mode fiber
Subscirber Connector
83
It is a small connector becoming pipular for use with single-mode fiber and also supports multi-mode fiber
Lucent Connector
84
It is a device that inkects test pulse of light into the cable and measures back scatter and reflection of light detected as a function of time
Optical Time Domain Reflectometer
85
What is an OTDR
Optical Time Domain Reflectometer
86
