Comment by generuso
4 days ago
The cable contains not only the fibers, but also optical amplifiers to compensate for the losses. Even for 24 fibers, the amplifier is a substantial and expensive piece of equipment. It also requires electric power, which is not trivial to provide along the entire span between continents.
And in short distance unrepeatered coastal festoon fiber systems where it's within normal DWDM system reach, node to node with no active underwater electronics, those are also often in areas with relatively low population/traffic that won't need more than 8 or 12 fibers at absolute max on any leg in a chain or ring. Such as the Connected Coast project being built in British Columbia right now.
I'd be astonished if it runs into capacity problems with an ultimate upgrade capacity of being able to run at least 20 different 200 or 400 Gbps circuits per fiber pair if appropriately costly DWDM terminals are installed at each end of dark fiber. Not even if all the tiny towns and cities that it hits were to magically quadruple in population.
12 is ridiculously low without the repeater concern. It seriously should cost a rounding error more to put 400, maybe 4000 fibers in that cable because the cost of the fiber itself is literally nothing compared to the cable armour, boat hire and labour.