You are designing an optical network. Your goal is to ensure that your design contains the highest degree of resiliency. In which two ways should you leverage a wavelength-switched optical network…

Question

Options

• Aa wavelength-switched optical network guarantees restoration based strictly on the shortest path
• Ba wavelength-switched optical network provides fault tolerance for single failures only
• Ca wavelength-switched optical network takes linear and nonlinear optical impairment calculation
• Da wavelength-switched optical network assigns routing and wavelength information
• Ea wavelength-switched optical network eliminates the need for dispersion compensating units in a

Explanation

C and D are the correct answers.

Why C and D are correct: A wavelength-switched optical network (WSON) enhances resiliency by incorporating optical impairment-aware routing (C) - it accounts for both linear impairments (chromatic dispersion, attenuation) and nonlinear impairments (four-wave mixing, cross-phase modulation) when computing paths, ensuring selected paths are physically viable. WSON also performs routing and wavelength assignment (RWA) (D), meaning it jointly selects both the route and the specific wavelength/lambda for each connection, which is the defining function of WSON and critical for maximizing network resource utilization and rerouting options.

Why the distractors are wrong:

• A is wrong because WSON does not restrict restoration to the shortest path - it uses constraint-based routing that weighs wavelength availability and optical impairments, which may favor a longer but more viable path.
• B is wrong because WSON is not limited to single-failure protection; it can handle diverse failure scenarios through its flexible RWA computation.
• E is wrong because WSON accounts for dispersion in its impairment calculations but does not eliminate the physical need for dispersion compensating units (DCUs) in the network.

Memory tip: Think of WSON as a "smart GPS for light" - it picks both the road (route) and the lane (wavelength), while checking for road hazards (optical impairments). It's not a simple shortest-path algorithm, and it doesn't magically remove hardware like DCUs.

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