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？（）

单项选择题The ONS 15216 is a 32-channel system. The ONS 15216 OADMs are capable of adding and dropping one， two， or four channels.  How are the OADMs provisioned to add and drop specific channels？（）

A. The ONS 15216 OADM can be provisioned to add/drop one， two， or four channels via Cisco Transport Manager （CTM）.
B. The ONS 15216 OADM consists only of a four-channel module， and the number of ports utilized determines whether it is a one， two， or four channel OADM.
C. Three separate OADM modules are available for one， two， and four channels. The wavelengths to be dropped and added are programmable via Cisco Transport Manager （CTM）.
D. The ONS 15216 OADM consists only of a single-channel module. Two-channel and four-channel support is available by stacking the single-channel module.
E. The ONS 15216 OADM is available in one， two， four channels.  There are 32 single-channel OADM modules， 16 two-channel OADM modules， and 8 four-channel OADM modules.

多项选择题Whatarethreerelevantdesignconsiderationswhenusingthe15216EDFA？（）

A. dispersion
B. Optical SNR
C. span attenuation
D. four wave mixing
E. receiver sensitivity

单项选择题Ifthepoweris0dBm，whatisthepowerinmW？（）

A. 0 mW
B. 1 mW
C. 10 mW
D. 1.5 mW

单项选择题Whatisanadvantageofanexternallymodulatedlaseroveradirectlymodulatedlaser？（）

A. lower cost
B. higher chirp
C. easier to manufacture
D. higher dispersion tolerance
E. higher optical signal-to-noise ratio

单项选择题Whatisthephenomenoncalledwheredifferentwavelengthsoflighttravelatdifferentspeeds？（）

A. OSNR
B. dispersion
C. light skew
D. attenuation