The following description of the operation of the device, the error is:

Which of the following reasons may cause a business error? (Multiple choice)

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?

Which of the following alarms trigger optical line protection switching?

In a typical chained NG WDM network (such as A -> B -> C, A, B, and C are three sites), it is found that the official telephone number between the stations is not available during the commissioning. What are the possible reasons? (Multiple choice)