A. fibers are terminated incorrectly on a node
B. the channel number in the received K1 byte is not identical to the channel number transmitted in the K2 byte
C. the channel number in the received C1 byte is not identical to the channel number transmitted in the C2 byte
D. the channel number in the received C2 byte is not identical to the channel number transmitted in the C1 byte
E. the channel number in the received K2 byte is not identical to the channel number transmitted in the K1 byte

A.255
B.512
C.1024
D.4096

A.line timing
B.loop timing
C.internal timing
D.through timing
E.external timing

A.2
B.3
C.4
D.20
E.22
F.24

A. VT circuits
B. STS circuits
C. VT tunnel circuits
D. 1:1 protection circuits
E. 1:N protection circuits

A.2；0
B.3；2
C.3；5
D.4；0
E.6；0
F.6；2

A. Slot 2 and Slot 4
B. Slot 4 and Slot 6
C. Slots 5 or 13 only
D. Slot 16 and Slot 17

A.1+0
B.1+1
C.1：1
D.1：N

A.0
B.1
C.2
D.3
E.4

A. signal fail, signal degrade, manual switch
B. signal degrade, signal fail, manual switch
C. protection lockout, manual switch, path AIS
D. forced switch, manual switch, signal degrade
E. protection lockout, manual switch, forced switch

A. Switch times would exceed 50 ms for an OC-3 BLSR ring.
B. An equal amount of working and protect bandwidth is required.
C. DCC bandwidth is not large enough to handle K1/K2 processing.
D. There is not enough bandwidth in an OC-3 ring to justify BLSR protection.