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Zorluk: OrtaTroubleshooting Physical Cabling and Connectors

A network administrator is troubleshooting an issue with a newly deployed Power over Ethernet (PoE+) pan-tilt-zoom (PTZ) IP camera installed at the end of a 85-meter Category 6 UTP cable run. The camera initializes and streams video normally during daylight, but repeatedly reboots whenever its infrared (IR) illuminators turn on at night. A basic wiremapper confirms all eight conductors have pin-to-pin continuity and proper T568B pinout. Which TWO of the following physical layer causes or diagnostic approaches are most appropriate to identify and resolve this failure?

  1. Using a cable certifier capable of testing DC resistance unbalance across conductor pairs to check for high resistance in the cable run.Cevap
  2. B
    Using a tone generator and inductive probe set to pinpoint the distance to a suspected conductor split or break along the horizontal cabling.
  3. Verifying whether Copper-Clad Aluminum (CCA) cabling was installed instead of solid bare copper conductors for the long horizontal run.Cevap
  4. D
    Manually locking the switchport speed and duplex to 100Mbps full-duplex to eliminate auto-negotiation failures causing excessive frame check sequence (FCS) errors.

Cevap

The correct approaches are using a cable certifier to test DC resistance unbalance and verifying that solid bare copper cabling was used instead of Copper-Clad Aluminum (CCA) wire.
The combination of daytime operation and nighttime reboots indicates that data transmission works fine, but power delivery fails when current demand increases. Cable certifiers that measure DC resistance unbalance evaluate the cable's electrical resistance under load, identifying high-resistance points. Furthermore, verifying that solid bare copper (rather than Copper-Clad Aluminum) was installed addresses the root cause, as CCA cabling exhibits much higher resistance, violating TIA standards and leading to significant voltage drops over long runs.

Adım Adım Çözüm

1
Analyze the reported failure symptoms
The IP camera functions during low-power daytime operations but reboots when high-power IR illuminators engage at night, indicating a voltage drop under higher current draw (PoE+ power delivery issue).
Wiremappers only verify basic pin continuity at negligible electrical current; they cannot detect high DC resistance under load.
2
Evaluate physical cable properties affecting PoE delivery
Substandard cabling materials like Copper-Clad Aluminum (CCA) have much higher resistance than pure copper, which causes excessive voltage drops over long distances (such as 85 meters).
ANSI/TIA standards explicitly require solid copper conductors for horizontal cabling carrying PoE.
3
Select the appropriate diagnostic tool for advanced electrical testing
A advanced cable certifier measures DC resistance and DC resistance unbalance between conductor pairs.
This pinpoints poor terminations, oxidized punch-downs, or improper cable gauge/material causing power delivery failures.

Anahtar Kavram

DC Resistance and PoE Troubleshooting in Twisted-Pair Cabling
Tahmini Süre:1m 30s
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Troubleshooting Physical Cabling and Connectors

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