SONET Path Terminating Equipment (PTE) requires which three line codes to be supported for DS1 and DS3 circuits?（） (Choose three.)

单项选择题Which timing mode is appropriate for a SONET NE that is adjacent to a SONET NE using BITS-1 timing source?（）

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

单项选择题If node 2 is accepting line timing from node 1, node 2 will send （）to node 1 as its SSM message.

A. ESF
B. PRS
C. DUS
D. SMC
E. B8ZS

单项选择题SONET Code Violations (CVs) totals in the PM tables are actually an accumulation of the number of （）.

A. J0 errors detected in a specified interval
B. errors detected in a given Errored Second (ES)
C. errors detected in a given Severely Errored Second (SES)
D. errors the encryption algorithm detects in a specified interval
E. Bit Interleaved Parity (BIP) errors detected in a specified interval

单项选择题Scrambling of SONET signals is done to （）.

A. prevent the leakage of external fiber emissions
B. provide the optical network with the highest level of security possible
C. assure an even distribution of 1's and 0's for extended transmitter life
D. assure an adequate number of transitions for clock recovery at the receiver
E. prevent the receiver from assuming AIS inadvertently when all 0's are received

单项选择题A Channel ID mismatch occurs when （）.

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