The preamble of the Ethernet frame structure is 7 bytes long, and the bit pattern of each byte is
10101010.

SES: There are 5% or more error blocks or at least one defect (OCI/AIS/LCKYAE/LTC/TIM/PLM) within one second.

Which of the following is the reason why the pump light output power of the RAMAN amplifier is very high?

Which of the following correctly describes the order in which the signal flow between the SDH interface and the cross-unit passes through the module units?

Self-healing means that when a network failure occurs, the network automatically recovers from the failure in a very short time (ITU-T stipulates that it is within ()) without human intervention, so that users can hardly feel that the network has failed.