Physical Layer Troubleshooting

Question 1

Physical Troubleshooting: bad cables or connectors

Answer 1

fault cables or fault connectors, could also imply use of an incorrect category of cable being used for a specific purpose

Question 2

Physical Troubleshooting: bad port

Answer 2

port may be bad, can easily confirm using the network connection LED and status indicators

Question 3

Physical Troubleshooting: opens and shorts

Answer 3

open: broken strand of copper, preventing current from flowing through a circuit
short: occurs when two copper connectors touch each other, resulting in current flowing through that short, rather than the attached electrical circuit because the short has lower resistance

Question 4

Physical Troubleshooting: splitting pairs in a cable

Answer 4

UTP cable has 8 copper leads, only 4 of 8 are used for data (2 transmit, 2 receive)
Some installers use the other 4 leads to support a second ethernet connection on another UTP cable - can function, but isnt standard

Question 5

Physical Troubleshooting: dB loss

Answer 5

loss of signal power, could result from exceeding the distance limitation of a copper or fiber cable

Question 6

Physical Troubleshooting: Transposed Tx/Rx leads

Answer 6

some switches support Medium Dependent Interface Crossover (MDIX), allows a switch port to properly configure its leads as transmit (Tx) or receive (Rx) leads
Can connect some with a straight through cable (instead of crossover cable)

Question 7

Physical Troubleshooting: Cable Placement

Answer 7

copper cables are subject to EMI, arrange cables to minimize interference - shouldnt be places near high voltage cables, generators, motors, or radio transmitters

Question 8

Physical Troubleshooting: distance limitations exceeded

Answer 8

transmission can be degraded if devices are using cable that exceeds the ethernet distance limitations for the cable type

Question 9

Physical Troubleshooting: crosstalk

Answer 9

can occur when an analog connection creates an electromagnetic field around its conductors, inducing waveforms - most common in analog phone call

Question 10

Physical Troubleshooting: speed/duplex mismatch

Answer 10

tricky to troubleshoot, connectivity is still maintained but at unacceptable levels

Question 11

Physical Troubleshooting: transceiver mismatch

Answer 11

transceivers must be selected carefully to ensure compatibility with the cable type and wavelength in use