What are the advantages of DWDM compared to CWDM? (Multiple Choice)

Question

Options

• ALarge capacity
• BLong distance transmission
• CSmooth expansion capability
• DEconomy and reliability

• A
  100% (54)

Explanation

All four options are correct because DWDM (Dense WDM) outperforms CWDM (Coarse WDM) across every major dimension. A (Large capacity): DWDM packs 40–160+ channels at ~0.8 nm spacing versus CWDM's maximum ~18 channels at 20 nm spacing, multiplying throughput dramatically. B (Long distance): DWDM operates in the C/L-band (1530–1625 nm), which aligns with EDFA (erbium-doped fiber amplifier) gain windows-enabling amplified, multi-thousand-kilometer links that CWDM cannot achieve. C (Smooth expansion): DWDM systems let you light new channels incrementally on existing fiber without replacing hardware, so capacity grows with demand. D (Economy and reliability): Although DWDM has higher per-port costs, its cost-per-bit drops significantly at scale, and its mature ecosystem offers robust protection switching and redundancy-making it more economical and reliable for backbone networks.

Since all four options are correct here, there are no wrong distractors-this is a "select all that apply" question where every listed feature genuinely favors DWDM.

Memory tip: Think of DWDM as the "highway" upgrade over CWDM's "country road"-more lanes (capacity), longer range (distance), easy on-ramps (expansion), and better cost-per-car at scale (economy/reliability). If DWDM wins in a category, pick it.

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