This CoriantTypesYesNo switch (default no) controls whether an STM-64 (10 Gb/s SDH) client port shuts down its client-facing transmit signal in response to certain upstream fault conditions, rather than continuing to send a signal the far end can no longer trust. An administrator enables this so a downstream client device sees a clean loss-of-signal and can fail over to a protection path instead of receiving a corrupted or stale signal. For example, enabling client-shutdown on STM-64 means that if the trunk carrying this client fails, the client transmitter is deliberately turned off so the attached router or switch immediately detects the outage and reroutes traffic.