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