The frame structure of 0DU4 is four times that of ODU1.

• A.FALSE
• B.TRUE

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The section overhead of STM-4 is () bytes/frame.

• A.9*8
• B.9*8*4
• C.9*9*8
• D.9*9*4

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Which of the following is the frame whose VC-4 J1 byte is indicated by the current frame's AU pointer?

• A.Previous frame
• B.None of the above
• C.Next frame
• D.Current frame

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The 1310 nm and 1550 nm transmission windows are low-loss windows. In DWDM systems, only the 1550 nm transmission window is used. Which of the following is the major cause?

• A.The non-linear effect of the 1550 nm wavelength area is small.
• B.The working wavelength flatness area of the EDFA is included in this window.
• C.None of the above
• D.The 1550 nm wavelength area is applicable to long-haul transmission.

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Forced switching, fiber cut switching, manual switching, and exercise switching are in the descending order of priority.

• A.TRUE
• B.FALSE

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