In the OTUk frame structure, which of the following alarms are related to segment monitoring? (Multiple choice)

For a system with an optical amplifier, the upper threshold of the received optical power of the wavelength division side of the OTU single board and the line single board (APD type receiving laser) is -3 dB at the receiving overload point of the optical module.

In unstructured emulation mode (SAToP), WS-OTN equipment provides the function of compressing idle 64 Kbit/s time slots in E1 signals to save transmission bandwidth.

The basic principle of MSTP equipment fault location is? (Multiple choice)

Which options are wrong in the following description about the ROADM board? (Multiple choice)