多项选择题
A. dispersion
B. Optical SNR
C. span attenuation
D. four wave mixing
E. receiver sensitivity
单项选择题 UPSR protection switching is initiated by （）, while BLSR is initiated by （）.
单项选择题 On an ONS 15454 node you can tunnel an （）.
单项选择题 In order to avoid misconnections due to a failed node in a Bidirectional Line Switched Ring (BLSR), Alarm Indication Signals (AISs) are sent on every channel normally terminating in that node. What is the name of this process?（）