Refer to the table. A customer investigates connectivity options for a DCI between two production data centers. The solution must provide dual 10G connections between locations with no single points…

Metro Ethernet bills per provisioned circuit, so scaling to 20 separate 10G connections in Year 2 requires provisioning 20 individual circuits, driving total cost well above a DWDM solution that adds wavelengths on existing fiber.

DWDM carries dozens to hundreds of wavelengths on a single fiber pair, so the Day 1 dual 10G requirement uses only two wavelengths while the same physical fiber plant can scale to 20 or more 10G channels in Year 2 by adding transponders. This avoids the per-circuit recurring costs of Metro Ethernet or MPLS when scaling, and unlike CWDM, DWDM supports enough tightly spaced channels (0.8 nm spacing) to accommodate 20 resilient paths including isolated SAN over IP and dedicated replication circuits.

CWDM uses wider 20 nm channel spacing and typically supports only 8 to 18 wavelengths per fiber pair, making it insufficient to scale to 20 resilient 10G connections and more expensive per wavelength at higher channel counts than DWDM.

MPLS is a Layer 3 service with per-circuit provisioning costs and bandwidth-based pricing that becomes significantly more expensive than DWDM when scaling to 20 high-capacity dedicated circuits over two years.