10. Physical Layer Flashcards
What connection must be established before any network communications can occur?
- A physical connection to a local network
- It can be wired or wireless depending on the setup of the network
What things that enables a device to connect to a network?
- Network Interface Card ( NIC )
- Some device may have just one NIC, while others may have multiple NICs
- Not al physical connections ofter the same level of performance
Where does the Physical Layer accepts the complete frame from?
- Data Link Layer
- Then encodes it as a series of signals that are transmitted to the local media
What layer is the last step in the encapsulation?
- Physical Layer
What does physical layer do?
- Transport bits across the network media
Who governed the TCP/IP standards?
- IETF
What organizations manages physical layer standards?
- ISO
- EIA/TIA
- ITU-T
- ANSI
- IEEE
List out the 3 functional areas for Physical Layer Standards
- Physical Components
- Encoding
- Signaling
What does encoding do?
- Conversts the stram of bits into a format recognizable by the next device in the network path
- It provides predictable patterns that can be recognized by the next device
List out the encoding methods
- Manchester
- 4B/5B
- 8B/10B
What does signaling do?
- How the bit values, “1” and “0” are represented on the physical medium
- It can be vary based on the type of medium being used
What is bandwidth?
- The capacity at which a medium can carry data
What components play a role in determining available bandwidth? ( 3 )
- Physical media properties
- Current technologies
- Laws of Physics
What does 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
Explain latency
- Amount of time ( delays ) for data to travel from one given point to another
Explain Throughput
- The measure of the transfer of bits across the media over a given period of time
- Rate at which data is successfully transferred from one location to another over a network within a specified time period.
Explain Goodput and how to calculate it
- The measure of usable data transferred over a given period of time
- Goodput = Throughput - Traffic Overhead ( Latency )
What is the most common type of cabling used in networks today?
- Copper Cabling
What is the advantages of Copper Cabling? ( 3 )
- Not expensive
- Easy to install
- Low resistance to electrical current flow
What is the limitataions of coper cabling?
- Attenuation
- The longer the electrical signals have to traverl, the weaker they get
- Electromagnetic Interference ( EMI ) and Radio Frequency Interference ( RFI ) can distort and corrupt the data signals
How to mitigate the limitations of copper cabling ? ( 3 )
- Strict adherence to cable length limits will mitigate attenuation
- Some kinds of copper cable mitigate EMI and RFI by using metallic sheilding and grounding
- Some kinds of copper cable mitigate crosstalk by twisting opposing circult pair wires together
List out the methods for copper cabling ( 3 )
- Unshielded Twisted-Pair ( UTP )
- Shielded Twisted-Pair ( STP )
- Coaxial Cable
What copper cabling methods is the most common networking media?
- Unshielded Twisted Pair ( UTP )
- Interconnects hosts with intermediary network devices
What does UTP terminated with ? ( What type of connectors )
- RJ-45
List out the 3 key characteristics of UTP
- The outer jacket protects the copper wires from physical damage
- Twisted pairs protect the signal from interference
- Color-coded plastic insulation electrically isolates the wires from each other and identifies each pair
List out 3 comparison between STP and UTP
- Better noise protection than UTP
- More expensive than UTP
- Harder to install than UTP
- Interconnects hosts with intermediary network devices
What does STP terminated with ? ( What type of connectors )
- RJ-45
List out the 4 key characteristics of STP
- The outer jacket protects the copper wires from physical damage
- Braided or Foil Sheild provides EMI/RFI protection
- Foil shield for each pair of each wires provides EMI/RFI protection
- Color-coded plastic insulation electrically isolates the wires from each other and identifies each pair
List out the 4 key characteristics of Coasial Cable
- Outer Cable Jacket to prevent minor physical damage
- A woven copper braid, or metallic foil, acts as the second wire in the circuit and as a shield for the inner conductor
- A layer of flexible plastic insulation
- A copper conductor is used to transmit the electronic signals
List out the connectors for Coaxial Connectors
- BNC
- N type
- F type
- Coaxial can be used in Wireless Installations ( Antennas ) or Cable internet installations
What does UTP relies 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
What is the standards for UTP? Who created the standards?
- TIA/EIA - 568 Standards
- TIA/EIA
What are the TIA/EIA - 568 Standards standardizes elements?
- Cable Types
- Cable Lengths
- Connectors
- Cable Termination
- Testing Methods
Who established the electrical standards for copper cabling?
- IEEE
List out the examples for Electrical Standards ( 3 )
- Category 3
- Category 5 and 5e
- Category 6
List out all the cable colors for copper cable
- Green
- Green White
- Brown
- Brown White
- Blue
- Blue White
- Orange
- Orange White
List out the cables allocation difference between Copper Straight-Through and Crossover
- Straight Through - Pair 2 ( Orange )
- Crossover - Pair 3 ( Green )
- Slide 25
What is the standard for Copper Straight Through ?
- Both ends T568A or T568B
- Host to Network Device
What is the standard for Copper Crossover ?
- One end with T568A, while other end with T568B
- Host-to-host, Switch-to-switch, router-to-router
Why is Fiber-Optic Cabling not as common as UTP?
- Because the expense involved
- It is ideal for some networking scenarios
What is the advantages of Fiber-Optic Cabling? ( 2 )
- Transmits data over longer distances at higher bandwidth than any other networking media
- Less susceptible to attenuation, and completely immune to EMI/RFI
What is Fiber-Optic Cabling made of?
- Flexible, extremely thin strands of very pure glass
How does Fiber-Optic Cabling encodes bits as pulses of light? ( 2 )
- Uses a laser
- LED to encode bits as pulses of light
- It acts as a wave guide to transmit light betwen the two ends with minimal signal loss
List out the 2 types of Fiber Media
- Single-Mode Fiber
- Multimode Fiber
What is the description for Single-Mode Fiber? ( 3 )
- Very small core
- Uses expensive lasers
- Long distance applicators
What is the description for Multimode Fiber? ( 3 )
- Larger Core
- Uses less expensive LEDs
- LED’s transmit ar different angles
- Up to 10 Gbps over 550 meters
What does dispersion refers to?
- The spreading out of a light pulse over tim.
List out the 4 types of industry for Fiber-Optic Cabling
- Enterprise Networks
- Fiber-to-the-Home
- Long-Haul Networks
- Submarine Cable Network
What does Enterprise Networks used for?
- Backbone cabling applcations and interconnection infrastructure devices
What does Fiber-to-the-Home ( FTTH ) ?
- Used to provide always-on broadband services to homes and small businesses
What does Long-Haul Networks used for?
- Used by service provides to connect countries and cities
What does Submarine Cable Networks used to?
- Used to provide reliable high-speed, high-capacity solutions capable of surviving in harsh undersea environment at up to transoceanic distances
What is the bandwidth between UTP cabling and Fibe-Optic Cabling?
- UTP Cabling ( 10 Mb/s - 10 GB/s )
- Fiber-Optic Cabling ( 10Mb/s - 100 CB/s )
What is the distance between UTP cabling and Fiber-Optic Cabling?
- UTP , Relatively Short ( 1 - 100 meters )
- Fiber-Optic Cabling , Relatively Long ( 1 - 100,000 meters )
What is immune to EMI and RFI UTP cabling or Fiber-Optic Cabling?
- Fiber-Optic Cabling
What is immune to Immunity to electrical hazards UTP cabling or Fiber-Optic Cabling?
- Fiber-Optic Cabling
What has the highest media and connector costs?
- Fiber-Optic Cabling
What has the highest installation skills required?
- Fiber-Optic Cabling
What is the highest Safety Precautions?
- Fiber-Optic Cabling
List out the limitations of wireless media
- 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 comon 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 onw device can send or receive at a time. Many users accessing the WLAN simultaneously results in reduced bandwidth for each user.
What does Wireless Media carries?
- Carries electromagnetic signals representing binary digits using radio or microwave frequencies
- This provides the greatest mobility option
- Wireless connection numbers continue to increase
What organizations cover both the data link and physical layer for wireless data communications?
- IEEE
- Telecommunications
List out the specifications that physical layer dictate
- Data to radio signal encoding methods
- Frequency and power of transmission
- Signal reception and decoding requirements
- Antenna design and construction
List out the wireless standards ( 4 )
- 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
List out the required devices for Wireless LAN ( WLAN ) ( 2 )
- 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
What must be considered when purchasing WLAN equipment?
- Compatibility
- Interoperability
