How to detect and diagnose cabling problems using Time Domain Reflector (TDR) in Cisco devices

Goal: diagnose and resolve cabling problems
What it does: The device sends a signal through the cable and compares the reflected signal to the initial signal sent.

Important:
- Only works with 10/100/1000 copper
- SFP and copper 10/100 not supported

- Run it with the IOS Command:
test cable-diagnostics tdr interface <..>
show cable-diagnostics tdr interface

TDR will detect these cabling problems:
- Open, broken, or cut twisted-pair wires. The wires are not connected to the wires from the remote device.
- Shorted twisted-pair wires. The wires are touching each other or the wires from the remote device.

Example:
SWITCH# test cable-diagnostics tdr interface GigabitEthernet 1/0/47
TDR test started on interface Gi1/0/47
A TDR test can take a few seconds to run on an interface
Use 'show cable-diagnostics tdr' to read the TDR results.

SWITCH#show cable-diagnostics tdr interface GigabitEthernet 1/0/47
TDR test last run on: March 04 19:37:15

Interface Speed Local pair Pair length Remote pair Pair status
--------- ----- ---------- ------------------ ----------- --------------------
Gi1/0/47 1000M Pair A 0 +/- 10 meters Pair B Normal
Pair B 0 +/- 10 meters Pair A Normal
Pair C 0 +/- 10 meters Pair D Normal
Pair D 0 +/- 10 meters Pair C Normal


The PRBS test can only be executed for TenG interfaces:
SWITCH# test cable-diagnostics prbs start interface TenGigabitEthernet ?
<1-9> TenGigabitEthernet interface number