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)

Which of the following description of the PM_BIP8 related alarm is correct?

OLA sites can also use ESC.

For the relay type OTU, the alarms of all SM segments are terminated at the local station and are not transmitted downstream (except for OTUkLOF to insert ODUk_PI_AIS downstream). Other alarms continue to be transmitted to the downstream station and reported on the WDM side of the OTU (except for R_LOS to insert ODUK_PM_AIS to the downstream site).

Daily equipment maintenance items, excluding: