Compared with WDM, which of the following options are the advantages of OTN? (Multiple choice)

TU-AIS is often encountered during network maintenance. Which of the following alarms can trigger a TU-AIS alarm? (Multiple choice)

Which of the following options meet the advantages of erbium-doped fiber amplifiers? (Multiple choice)

In OSN550, the CX slot contains a function board integrating the system control and communication (SCC) unit, the cross-connect unit and the clock unit. There are many types of function boards according to the functions and access functions provided by OSN550.

Which of the following statements about Multiplexed Section Remote Error Indication (MS-REI) are correct?
① The B2 byte indicates the transmission channel.
② The M1 byte indicates the transmission channel.
③ MS-REI is sent from the sink to the source.
④ MS-REI is transmitted from the source to the receiver.
Indicates the number of bit errors detected by the receiver after receiving the MS signal.