During the process of maintaining the OSN device, it is often seen that the fan runs at full speed, and the device reports the TEMP_OVER alarm. What are the common causes and treatment methods?

The wave division system complement to chromatic dispersion mainly adopts the DCM compensation method. The following statements about DCM dispersion compensation, which is wrong?

Which of the following monitoring boards do not support 1588v2 signal processing and transparent transmission?

After starting the extended SSM protocol, in addition to determining the clock quality level and priority, the clock ID is also determined. After receiving the clock signal with the ID, the network element considers that the source is unavailable if it is judged to be the clock signal sent by the station. In this way, even after passing through multiple sites, the network element can still recognize the clock signal sent by itself, preventing the formation of a timing loop.

For the wavelength division system, configure the 1st-20th wave, use the NS4 single board, and test the M40 output port with the spectrum analyzer during the commissioning. It is found that the optical power of the 20th wave is significantly lower than the other 19 waves. The possible reasons are as follows: (Multiple Choice)