In SDH， what is the name of the embedded Data Communication Channel （DCC） in bytes D1-D3？（）

单项选择题SDHCodeViolations（CVs）totalsinthePMtablesareactuallyanaccumulationofthenumberof（）.

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

多项选择题Click the Exhibit button. The exhibit shows a 15454 15216 DWDM system and alarm indications.  What are two possible sources of trouble shown in the system？（）

A. fiber failure between Sites A and D
B. EDFA failure at Site A （clockwise direction）
C. EDFA failure at Site C （clockwise direction）
D. 15216 multiplexer at Site A （counter-clockwise direction）
E. OADM pass-through （West "OUT"） failure at site D （clockwise）
F. wavelengths 1 and 3 transmitter failures at Site A （clockwise direction）

多项选择题Whataretwoimportantconsiderationswhenusing2-or4-channel15216OADMs？（）

A. All "Add" channels require uniform power levels.
B. The flexibility of wavelengths per OADM is limited.
C. It is easier to balance "Pass-Through" and "Add" channels.
D. There is lower pass-through loss using multi-channel OADMs.
E. You can extract a single channel without dropping other channels.

单项选择题Click the Exhibit button. What is the maximum allowable loss budget between the ONS 15216 Mux （left side） composite output and the ONS 15216 Demux （right side） composite input，  with the optical values given in the exhibit？ （Assume the worst case loss of 4.5 dB for 15216 200 GHz Mux Demux and ignore power penalties or extra margin.）  （）

A. 15 dB
B. 17 dB
C. 21 dB
D. 26 dB
E. 27 dB

单项选择题A 2.5 Gb s （OC-48 or STM-16） optical signal with a dispersion tolerance of 1200 ps nm goes through fiber with 18ps nm*km of dispersion.  How many 15216-DCU-350 equivalents are needed for enough compensation after traveling 100 km？（）

A. none
B. one
C. two
D. three
E. four