CLI Reference Guide-R07

Chapter 11 | Interface Commands
Cable Diagnostics
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Low Alarm Low Warning High Warning High Alarm
----------- ------------ ------------ ------------ ------------
Temperature(Celsius) -123.00 0.00 70.00 75.00
Voltage(Volts) 3.10 3.15 3.45 3.50
Current(mA) 6.00 7.00 90.00 100.00
TxPower(dBm) -12.00 -11.50 -9.50 -9.00
RxPower(dBm) -21.50 -21.00 -3.50 -3.00
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: 1-22/48)
Command Mode
Privileged Exec
Command Usage
◆ Cable diagnostics are performed using an internal Digital Signal Processing test
process when the port link-up speed is 1 Gbps. The method analyses the cable
by sending a pulsed signal into the cable, and then examining the reflection of
that pulse. If the port link-up speed is not 1 Gbps, then Time Domain
Reflectometry (TDR) test method is used. TDR also detects a cable fault by
sending a signal through the cable and reading the signal that is reflected back.
However, note that TDR can only determine if a link is valid or faulty.
◆ This cable test is only accurate for Ethernet cables 7 - 100 meters long.
◆ The test takes approximately 5 seconds. Use the show cable-diagnostics
command to display the results of the test, including common cable failures, as
well as the status and approximate length of each cable pair.
◆ 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.