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Chapter 4
| Interface Configuration
Port Configuration
Performing
Cable Diagnostics
Use the Interface > Port > Cable Test page to test the cable attached to a port. The
cable test will check for any cable faults (short, open, etc.). If a fault is found, the
switch reports the length to the fault. Otherwise, it reports the cable length. It can
be used to determine the quality of the cable, connectors, and terminations.
Problems such as opens, shorts, and cable impedance mismatch can be diagnosed
with this test.
Command Usage
◆
Cable diagnostics are performed using Time Domain Reflectometry (TDR) test
methods. TDR analyses the cable by sending a pulsed signal into the cable, and
then examining the reflection of that pulse.
◆
This cable test is only accurate for Gigabit Ethernet cables 0 - 100 meters long.
◆
The test takes approximately 5 seconds. The switch displays the results of the
test immediately upon completion, including common cable failures, as well as
the status and approximate length to a fault.
◆
Potential conditions which may be listed by the diagnostics include:
OK: Correctly terminated pair
■
Open: Open pair, no link partner
■
Short: Shorted pair
■
Impedance mismatch: Terminating impedance is not in the reference
■
range.
◆
Ports are linked down while running cable diagnostics.
Parameters
These parameters are displayed:
◆
Port – Port identifier. (Range: 1-8/24)
◆
Type – Displays media type. (GE – Gigabit Ethernet)
◆
Link Status – Shows if the port link is up or down.
◆
Test Result – The results include common cable failures, as well as the status
and approximate distance to a fault, or the approximate cable length if no fault
is found.
To ensure more accurate measurement of the length to a fault, first disable
power-saving mode on the link partner before running cable diagnostics.
The reported distance to a fault is accurate to +/- 4 meters for most cables.
However, depending on cable quality, accuracy may be within +/- 6 meters.
◆
Last Updated – Shows the last time this port was tested.
– 110 –
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