[Denvercoder9]

Neither, it's shared ownership. It's similar to if you buy a house with your partner: neither of you owns specific rooms, but you own the whole thing together. There's likely agreements about which fibers (there's 8 fiber pairs in the cable) and/or how much bandwidth everyone can use, though.

[foepys]

Why only 8? Why don't they put like 100 in there?

[bogomipz]

Well, cost for one. If that fiber isn't being used it's a terrible investment. But more generally it's probably not needed. The bandwidth of optical fibre is theoretically unlimited. A single fibre carries many wavelengths, a wave length is like a channel. This is known as DWDM(dense wave division multiplexing.) A single wavelength commonly caries 100 Gbs. Although recently advances have shown 700 Gbs for a single wavelength[1]. The number of wavelengths and hence bandwidth depends on the transmission gear used on both ends of the cable. You can upgrade the bandwidth by upgrading the transmission gear. The state of the art for years has been 8 pair systems but more recently developments have produced 24 and 36 pair systems.

[1] https://www.lightwaveonline.com/network-design/high-speed-ne...

[tiernano]

IIRC, it's mostly to do with power... every Xkm (100?) they need to put a power amp and have to splice 100 pairs at each point...

[cure]

Presumably because the cable would be (much) heavier and thicker.

There is some movement towards having more pairs in newer cables, e.g. the Grace Hopper will have 16 pairs, cf. https://cloud.google.com/blog/products/infrastructure/announ...

[shrubble]

Look up how DWDM works; they don't need more than 8. The optical gear that goes on land, keeps getting more capable of driving ever more bandwidth over the same fiber...

[tragictrash]

Don't the inline amplifiers need to be upgraded too?

[willcipriano]

They didn't need 500+ terabits?