Channelmania! – future proof your DWDM network topology while keeping it flexible for 1.6T#

Thomas Weible

• Why: Planning DWDM channel grids for the 400G → 800G → 1.6T superchannel era is exactly the kind of physical-layer topology tradeoff the PM cares about — this is about how fibre capacity and reconfigurability interact over a 10+ year horizon.
• What: An argument for moving to 400GHz channel grids: how the shift from narrow grids (200/100/50/25GHz) to wide-grid superchannels changes topology economics, how coherent detection being "blind" to anything but its own wavelength enables filterless designs, and how to keep legacy ≤10G signals coexisting on the same fibre pair while avoiding expensive ROADMs (from abstract only).
• How: Wider fixed-grid (400GHz) filters plus coherent transceivers' tolerance of unfiltered neighbours: harvest filterless-topology cost benefits while retaining the flexibility to reassign bandwidth and carry legacy wavelengths.
• Where applicable: Any DWDM operator with long-haul or metro infrastructure planning a decade out. The tradeoff is explicit — reduced flexibility vs. cost — and the "keep 10G and below on the same fibre" constraint matters for networks with legacy OTN payloads. The talk may carry a vendor perspective; the physics and grid economics are general.