Chapter 10
| Interface Commands
Cable Diagnostics
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Options :
Console#
Cable Diagnostics
test cable-diagnostics This command performs cable diagnostics on the specified port to diagnose any
cable faults (short, open, etc.) and report the cable length.
Syntax
test cable-diagnostics interface interface
interface
ethernet unit/port
unit - Unit identifier. (Range: 1)
port - Port number. (Range: 1-24/48)
Command Mode
Privileged Exec
Command Usage
◆ Cable diagnostics are performed using Digital Signal Processing (DSP) test
methods. DSP 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 - 250 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 of each cable pair.
◆ Potential conditions which may be listed by the diagnostics include:
■
OK: Correctly terminated pair
■
Open: Open pair, no link partner
■
Short: Shorted pair
■
Not Supported: This message is displayed for Gigabit Ethernet ports linked
up at a speed lower than 1000 Mbps.
■
Impedance mismatch: Terminating impedance is not in the reference
range.
◆ Ports are linked down while running cable diagnostics.
◆ To ensure more accurate measurement of the length to a fault, first disable
power-saving mode (using the no power-save command) on the link partner
before running cable diagnostics.
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