Dispersion compensation is not required for 40 Gbit/s and 100 Gbit/s coherent systems because the dispersion tolerance of coherent boards is large. NG WDM products do not support hybrid transmission of non-coherent and coherent networks.

• A.False
• B.True

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

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Which of the following factors determine the optical signal-to-noise ratio (OSNR) of the receiving end to a certain extent? After a certain distance of signal transmission in the WDM system, the optical signal-to-noise ratio (OSNR) of the receiving end decreases to a certain extent. Which of the following is the main reason?

• A.Fiber attenuation is too high.
• B.Use multiplexers and demultiplexers.
• C.No new optical fiber is used.
• D.Use EDFA.

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For the SSM protocol, which of the following statements are correct? (Multiple choice)

• A.When the SSM protocol is not enabled, the clock network can only be configured as one-way and cannot be looped.
• B.When the standard SSM protocol is started, the clock network can be configured in both directions but cannot be looped.
• C.Whether to start the SSM protocol has little effect on the clock network.
• D.When the extended SSM protocol is started, the clock network can be configured in both directions and can be looped.

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Which of the following description of the extended ECC is correct? (Multiple Choice)

• A.In the automatic extended ECC mode, you need to connect the Ethernet ports of the two NEs with a direct-connected network cable (or a standard network cable through B), extend the ECC, and specify the server and client.
• B.The scale of the extended ECC network (the sum of the server and the client) must not exceed 8.
• C.Extended ECC recommends to use manual basis, which reduces mutual negotiation between network elements.
• D.Extended ECC is divided into automatic extended ECC and manual extended ECC. One network element can only support one mode at the same time. These two methods cannot be directly docked.

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