The power difference becomes 6 dB (2 dBm – (–4 dBm) = 6 dB), which exceeds the 5 dB threshold, so protection switching occurs.

A multimeter is used to verify the equipment’s electrical power and grounding.

An optical power meter measures the received optical power levels on each wavelength.

An optical spectrum analyzer checks the wavelength spacing, channel power, and spectral purity during WDM commissioning.

QPSK uses four phase states, not two. Statement B incorrectly says it assigns two possible phase values, which describes BPSK, not QPSK. QPSK effectively doubles the bits per symbol compared to BPSK, reducing baud rate while maintaining data rate, but with four distinct phases.

An abnormal TTI in the SM layer triggers a Trail Identifier Mismatch (TIM) alarm. AIS signals loss of signal, not a TTI mismatch.

The TNG2M60V board is not a 60-channel multiplexer with VOA for the Super C band; this description is incorrect for that board model.

A ROADM (Reconfigurable Optical Add-Drop Multiplexer) site is a key component in flexible optical networks. It allows the flexible adding and dropping of wavelengths within the site (A), enhancing network agility. It supports automatic optical power adjustment (B), which helps maintain signal quality across the network by balancing power levels and avoiding distortion. Also, when optical-layer ASON (Automatically Switched Optical Network) is required, ROADMs must be used (C) to provide dynamic wavelength routing and switching capabilities. However, ROADMs are not mandatory for electrical-layer ASON, so (D) is false. These features collectively enable efficient, dynamic optical networking with minimal manual intervention, critical in advanced transmission scenarios covered by HCIP-Transmission.

In 1+1 optical line protection configurations, either the RI1/TO1 path or the RI2/TO2 path can be designated as the working channel.

The OptiXtrans E6600 and OptiX OSN 1800 series use a hierarchical system architecture divided into three layers: L0 (optical layer), L1 (multiplexing layer), and L2 (service layer). According to HCIP-Transmission documentation, the E6608T/E6616 and OptiX OSN 1800 II TP/OSN 1800 V Pro models implement the L0+L1+L2 architecture, providing comprehensive functionality across optical signal management, multiplexing, and client service handling. This architecture enables scalable, flexible, and efficient transmission systems supporting various services and network demands. Other options mention partial model sets or incorrect combinations, making option B the accurate statement reflecting the system architecture.