Are you referring to Time Domain Reflectometry (TDR)?
That new feature is available and supported only on:
- Aruba 2930F switch series
- Aruba 3810M switch series
- Aruba 5400R zl2 (only on v3 zl2 Modules: J9986A, J9987A, J9989A, J9990A, J9991A - applicable only for ports 1–20, rest of the four ports are Smart Rate ports - and J9992A) switch series
If so, the TDR feature (see test cable-diagnostics <PORT-LIST> and show cable-diagnostics <PORT-LIST> commands) works only on 100BASE-TX and 1000BASE-T Copper ports (not Fiber Optic ports) of physical interfaces or Mini-GBIC (Copper) Transceivers.