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Difficulty: MediumTroubleshooting Physical Cabling and Connectors

A network technician is investigating degraded performance and intermittent packet drops on a newly terminated Category 6 UTP cable run. When tested with a basic wiremap continuity tester, all eight pins pass with direct 1-to-1 pin mapping. However, the link experiences severe performance issues under load. Which of the following test results or physical characteristics indicate that a split pair condition is the root cause of this failure? (Select TWO.)

  1. A basic wiremap continuity tester reports that pin 1 connects to pin 1, pin 2 to pin 2, up to pin 8 to pin 8.Answer
  2. A cable certifier measures excessively high Near-End Crosstalk (NEXT) along the cable run.Answer
  3. C
    A Time-Domain Reflectometer (TDR) displays a sharp impedance spike corresponding to a physical conductor break at 45 meters.
  4. D
    An optical power meter reports a loss of optical power exceeding the link loss budget.

Answer

The correct characteristics indicating a split pair are that a basic wiremap tester reports full 1-to-1 pin continuity, while a cable certifier measures excessively high Near-End Crosstalk (NEXT).
A split pair condition happens when individual wires from separate twisted pairs are improperly paired together at both RJ-45 terminations. Because the pinout sequence is mirrored at both ends, a basic continuity wiremap tester shows a valid 1-to-1 connection. However, breaking the geometric pairing cancels the noise rejection mechanism inherent to twisted-pair cabling, causing severe Near-End Crosstalk (NEXT) that requires a full cable certifier to detect.

Step-by-Step Solution

1
Understand the physical nature of a split pair fault.
A split pair occurs when two individual conductors from different twisted pairs are mistakenly swapped at both cable ends during termination (e.g., pin 3 and pin 4 swapped on both ends).
Because the miswiring is mirrored at both ends, electrical continuity is maintained from end to end.
2
Evaluate how basic continuity testers interact with split pairs.
Basic wiremap testers only verify DC continuity and pin-to-pin mapping, so they report the cable as correctly wired.
Continuity testers do not check signal frequency, phase cancellation, or crosstalk.
3
Analyze high-frequency signal interference caused by split pairs.
Twisting two specific conductors together cancels out electromagnetic interference. Splitting those pairs disrupts the cancellation effect, causing high Near-End Crosstalk (NEXT) and Far-End Crosstalk (FEXT).
Advanced cable certifiers testing high-frequency signal integrity detect this elevated NEXT noise.

Key Concept

Split Pair Diagnosis in Twisted-Pair Cabling
Estimated Time:1m 30s
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Topics

Troubleshooting Physical Cabling and Connectors

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