What are the characteristics of the application scenarios of optical layer ASON? (Multiple Choice)

Question

Options

• AThe optical cable is in good condition
• BLess fiber breakage
• COptical cable condition is poor
• DPMD large

• A
  75% (15)
• C
  15% (3)
• D
  10% (2)

Explanation

Optical layer ASON (Automatically Switched Optical Network) is suited for deployment where the underlying physical infrastructure is stable and reliable. Options A (good optical cable condition) and B (less fiber breakage) are correct because ASON at the optical layer leverages automatic switching and restoration for occasional failures - it works best when the baseline environment is healthy and disruptions are the exception, not the norm.

Why C is wrong: Poor optical cable condition creates frequent, unpredictable failures that overwhelm optical-layer ASON's restoration mechanisms. Such environments are better handled at higher network layers (e.g., IP/MPLS) with more robust fault management.

Why D is wrong: High PMD (Polarization Mode Dispersion) indicates fiber quality issues that degrade optical signal integrity regardless of switching capability. Large PMD is a physical impairment that ASON's control plane cannot compensate for - it's a hardware/fiber plant problem, not a routing problem.

Memory tip: Think of optical layer ASON as a "good neighborhood" technology - it thrives when the physical environment is already well-maintained (good cables, rare breaks), and it handles the occasional outage automatically. C and D both describe bad neighborhoods where the physical layer itself is the problem, making optical-layer automation insufficient.

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