In a WDM system, after a distance of transmission, the OSNR of the signals at the receive end decreases to a certain extent. Which of the following is the main cause?

• A.New optical fiber is not used.
• B.Use of EDFA
• C.Use of Demultiplexer Multiplexer
• D.The fiber attenuation is too large.

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Which layer of the TCP/IP protocol is the TCP/UDP protocol located?

• A.Network layer
• B.Transport layer
• C.Application layer
• D.Data link layer

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When the OSN 8800 needs to access GE signals, the boards that can be used are: (Multiple Choice)

• A.TSC
• B.TDX
• C.TEM28
• D.TOA

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Which of the following description of 1+1 optical line protection is wrong?

• A.The switching method defaults to non-recovery
• B.The switching mode defaults to double-ended switching
• C.The active and standby input light difference defaults to 5dB.
• D.The primary and secondary input lights initial difference defaults to 0.

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What are the basic principles of MSTP device fault location? (Multiple choice)

• A.Low speed first, then high speed
• B.Advanced first, then low level
• C.External first, then transfer
• D.Network first, then network element

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