OSN6800 from the sub-frame 2 of SCC reported veneer commun_fail alarm. Parameter No.3 bits is 0X04, NE is not detached, and the main subrack and slave subrack 1 has no abnormality alarm, what are the possible reasons? (Multiple choice)
A . The AUX board of the main subrack is faulty.
B . The AUX boards of the slave subrack 2 is faulty.
C . The AUX board of the slave subrack 3 is faulty.
D . The network cable between slave subrack 2 and 3 is faulty.
Answer: BCD