Lesson 4B Flashcards
What is the difference between speed and throughput in a network?
Speed: This is the rate at which data is sent over a network, measured in bits per second (bps). Examples are 10 Mbps or 1 Gbps.
Throughput: This is the actual speed at which data is delivered over the network, considering mistakes and delays. It’s usually less than the maximum speed.
What is baud rate?
Baud rate is the number of symbols (like flashes of a light) sent per second. It is measured in hertz (Hz). For example, 1 MHz means 1 million symbols per second.
What is attenuation in a network?
Attenuation is the loss of signal strength as it travels over a distance. It is measured in decibels (dB).
What is noise and how is it measured?
Noise is any unwanted signals that interfere with your main signal, making it harder to detect. It is measured as the signal-to-noise ratio (SNR), which shows how clear your signal is compared to the noise.
What should you check first if you have a link failure?
Patch Cables: Make sure they are connected properly. Try replacing them with known good cables.
Transceivers: Test them with a loopback tool or substitute with working ones.
What do the different LED lights on network devices mean?
Solid Green: Connected but not busy.
Flickering Green: Working normally with traffic.
No Light: Not working or turned off.
Blinking Amber: There’s a fault (e.g., too many collisions).
Solid Amber: The port is blocked to prevent loops.
What is a loopback plug and how is it used?
A loopback plug is a special tool that tests if a network port is working. It sends data from the port and checks if it comes back to the same port, showing if the port is good.
What is the purpose of a cable tester in network troubleshooting?
A cable tester helps diagnose issues with cables by checking physical and electrical properties. It reports on cable conditions, crosstalk, attenuation (signal loss), noise, resistance, and other characteristics. Some advanced testers, called certifiers, can verify if a cable meets specific performance standards, like TIA/EIA 568 Category 6A.
What should you check when troubleshooting a permanent link to ensure it works properly?
You should verify the cable type is appropriate for the application. For example, 10 GbE Ethernet needs a high-quality cable, not a basic Cat 5e cable. Also, check if the correct type of shielding is used, like shielded cables in environments with high interference. The cable jacket should match the installation location, such as plenum-rated for ceiling spaces and riser-rated for vertical spaces.
What does a network tone generator and probe do?
A network tone generator and probe help trace a cable through bundles or hidden areas. The tone generator sends a signal through the cable, and the probe picks up this signal to help you follow and identify the cable’s path. This tool is useful when cables are not labeled or are hard to reach.
How does a Time Domain Reflectometer (TDR) help in cable troubleshooting?
A TDR measures the length of a cable and finds problems like open circuits, short circuits, or kinks. It sends a signal down the cable and measures how long it takes for the signal to bounce back. This helps locate faults and determine their distance from the tester.
What is a wire map tester used for, and what problems can it identify?
A wire map tester checks if the wires in a cable are connected correctly. It can identify:
Continuity (Open): A wire is broken or not connected properly.
Short: Two wires are touching each other.
Incorrect Pin-Out: Wires are not connected to the correct pins.
Crossed Pair (TX/RX Reverse): Wires from one pair are connected to the wrong pins.
Split Pair: Wires in a pair are connected to different pairs.**
What is attenuation, and why is it important in cable performance?
Attenuation is the loss of signal strength as it travels through a cable. It is measured in decibels (dB). High attenuation can cause slow speeds and connectivity issues. For example, Cat 5e allows up to 24 dB of attenuation, while Cat 6 allows up to 21.7 dB. Lower dB values are better, meaning less signal loss.
How does electromagnetic interference (EMI) affect cables, and how can it be minimized?
EMI is interference from sources like electrical cables or motors that can disrupt the signal in a cable. To minimize EMI, ensure cables are installed away from potential interference sources and use shielded cables if needed. Proper installation helps reduce the impact of interference and keeps the network running smoothly.
What is crosstalk in networking cables?
Crosstalk is when signals from one wire interfere with signals in another wire. Imagine it like hearing two songs at once through headphones. It usually happens because of bad wiring or damaged cables.
