The viability of transporting alien wavelengths at 10 Gb/s is fundamentally based on the high degree of standardization for that technology. ITU-T recommendations, such as G.959.1, defined the physical layer interfaces for 10G DWDM systems. This resulted in transponders from various vendors exhibiting very similar optical performance characteristics, including the use of Non-Return-to-Zero (NRZ) modulation, comparable Optical Signal-to-Noise Ratio (OSNR) requirements, and chromatic dispersion tolerance. This interoperability is a hallmark of the 10G era and is the primary enabler for the alien wavelength use case, allowing a third-party signal to be successfully transported over a Nokia optical line system.

A. An alien wavelength is a desired, data-carrying optical service signal, not an unwanted signal generated by the Four-Wave Mixing (FWM) non-linear impairment.

C. A VAC (Variable Attenuator Channel) card is used for power equalization by attenuating signals. Comprehensive measurement is performed by an Optical Channel Monitor (OCM).

D. This statement is factually correct; alien wavelengths do not support Nokia's proprietary Wavelength Tracker. However, this is a vendor-specific operational detail, whereas option B describes the fundamental technological principle that enables 10G alien wavelengths in the first place.

1. ITU-T Recommendation G.959.1 (2012-03), "Optical transport network physical layer interfaces": This standard specifies the physical layer characteristics for various optical interfaces, including 10G DWDM. Section 8, "Transverse compatibility," details the parameters required for multi-vendor interoperability, which is the basis for the "similar optical performance" described in the correct answer.

2. Nokia 1830 PSS Product Information and Planning Guide, 3KC-01111-KAAA-TCZZA: This document describes the features of the Nokia optical transport platform. The sections on Wavelength Tracker specify that it requires Nokia transponders to embed a pilot tone, confirming that alien wavelengths (from third-party equipment) would not support this feature. This supports the reasoning for why option D is factually correct but less fundamental than B.

3. Nokia Application Note: "1830 PSS Alien Wavelengths": Documents of this nature detail the process for qualifying third-party signals. The need for a qualification process highlights that while performance is similar, it must be verified to ensure compatibility with the Nokia line system's transmission requirements (e.g., launch power, OSNR). This reinforces that performance characteristics are the central issue for alien wavelength transport.