This CoriantTypesYesNo switch (default no) controls whether a 10G WAN PHY client port framed as SONET 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 10G WAN SONET 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.