What are the advantages of OTN compared to WDM? (Multiple Choice)

Question

Options

• ABranches and lines are separated, and changes in customer interfaces do not affect line
• BHigh bandwidth utilization
• CPerfect reuse of small-granular services into large-granular pipelines
• DFlexible business scheduling

• A
  100% (16)

Explanation

All four options correctly describe OTN advantages over pure WDM, each addressing a different architectural layer.

A is correct because OTN's client/line separation (via the ODU wrapper) means upgrading a customer interface - say, from 10GE to 100GE - doesn't require reconfiguring the optical line layer; the two layers evolve independently. B is correct because OTN's tributary slot multiplexing packs multiple lower-rate services into a single high-capacity wavelength, avoiding the wasted capacity common in raw WDM where a wavelength is dedicated even when underutilized. C is correct because OTN's ODU hierarchy (ODU0 → ODU1 → ODU2 → ODU4) enables precise grooming - small-granularity services are efficiently nested into large-granularity pipelines with no stranded bandwidth. D is correct because OTN adds rich OAM overhead bytes on top of WDM, enabling end-to-end performance monitoring, protection switching, and flexible service provisioning that raw WDM cannot provide.

Since all four are correct, there are no wrong distractors - the exam is testing whether you recognize OTN's full value proposition across all dimensions.

Memory tip: Think of OTN as "WDM with a smart envelope" - the envelope (ODU wrapper) gives you Separation of layers, Better bandwidth use, Clean grooming of small services, and Dynamic management. SBCD = All correct.

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