Cisco Switch Cable Diagnostics

This command is useful to find out if any pairs are open. Just connect a device to the other end, and run the command:

Switch#test cable-diagnostics tdr interface g1/0/2
TDR test started on interface Gi1/0/2

It may take a few seconds to run. Then issue the following command:

Switch#show cable-diagnostics tdr interface gigabitEthernet g1/0/2
TDR test last run on: Oct 12 07:12:12

You should see some results like the following:

Interface    Speed    Local pair    Pair length    Remote pair    Pair status
---------    ------   ----------    -----------    -----------    -----------
Gi1/0/2        auto     Pair A        22 +/- 4 m         N/A       Open
Pair B        21 +/- 4 m         N/A       Open
Pair C        5 +/- 4 m          N/A       Open
Pair D        20 +/- 4 m         N/A       Open