2.6.7 - Crosstalk Issues

Flashcards covering key concepts related to crosstalk issues in network cabling.

Near End Crosstalk (NEXT)

Measures crosstalk on the receive pairs at the transmitter end, often due to excessive untwisting of pairs or faulty bonding of shielded elements.

Attenuation to Crosstalk Ratio, Near End (ACRN)

The difference between insertion loss and NEXT; equivalent to a signal-to-noise ratio (SNR).

Attenuation-to-Crosstalk Ratio, Far End (ACRF)

Far-end crosstalk (FEXT) measured on the receive pairs at the recipient end; the difference between insertion loss and FEXT gives ACRF.

Power Sum

Crosstalk calculations (PSNEXT, PSACRN, and PSACRF) confirm that a cable is suitable for Gigabit and 10 GbE Ethernet applications, using all four pairs.

Alien Crosstalk

Signal traffic from cables in close proximity that causes interference to a disturbed or victim cable.

Cinching a cable bundle too tightly and poorly terminated cabling.

What are common causes of alien crosstalk?

Crosstalk usually indicates a problem with:

Bad wiring, a bad connector, or improper termination.

Excessive untwisting at the ends and kinks or crush points along its run.

What visual cues should you check for when diagnosing crosstalk issues?

Less noise.

What is the meaning of higher values in crosstalk measurements (in dB)?

A break in the cable or a completely faulty installation.

What does a complete loss of connectivity usually indicate?

Attenuation, crosstalk, or noise.

What is intermittent loss of connectivity more likely caused by?