(totally disregarding the HSSG policy of talking cost and not price here)

All we see is price, don't forget step 3. Profit

If the cost estimate has any bearing on actual end-user purchase price, then I would say that the 3-4km reach alternative makes sense.

Consider C prices. If there are two parts there is scope to charge a lot more for 10km than if it was the only option 10km is a convenient distance for inter pop use around London Docklands, similarly around other IX. I guess over half our 10G fails the 4km spec

Having a 10km reach alternative costing 60% of 40km reach optics just doesn't make sense.

I'm in favour of less permutations of reach and package, a higher volume of fewer variants would reduce the cost of stocking spares which could be cheaper due to volume manufacture

Otoh if we need attenuators for 40km optics on 5km links then that's a complicating factor as well. That's not been needed before.

Engineering links increases cost. We can do 100G optics but it's still too hard to do auto link power adjustment? brandon