4 ms·

Is the cost of a single core with a 32 way splitter really a lot cheaper than a 32 core cable?

bcrl 3y ago
A 1x32 splitter costs somewhere between $20-70 (unless you pay exorbitant Corning prices). 32 core (well, 36 core) cables are cheap enough, but that's not what you need for a pure point to point network. Let's say you've got a local convergence point with 576 fibres facing the distribution network. With 1x32 splitters you need 18 feeder fibres. You can get a 24 core cable for $350/km. Now, let's say you're building a fully point to point network. You now need a 576 core cable for your feeder in the access network. That's going to cost north of $6000/km (that's a wild guess -- sorry, I don't have accurate numbers for high count cables as I haven't bought any in the past few years). If your access network is 10 km, that's the difference between $3,500 in cables vs $60,000 in cables. Plus you're adding a good $1,500-3,000/km in cost for larger splice closures and increased splicing labour. Where it really hurts is when you start getting close to your Central Office (CO). With P2P networks, you need more larger cables in the first few kilometers closest to the CO, which is often the most congested part of a network. For brownfield builds, that might require directional boring to install new conduit in a town to bring the new cables into the CO. That can get really expensive. Designing fibre networks is a game of whack-a-mole. Spending less on one component drives up costs on other components. Sure a P2P network means you can use cheaper SFPs, but the outside plant is more expensive. There's good reason that most carriers are building Passive Optical Networks -- P2P just isn't economically viable in all scenarios.
- matt-p 3y ago
  These maths are quite theoretical! In reality in a 1:32 PON you'll typically use somewhere between 14 and 30 ports (because typically you want to leave at least one spare port). In rural areas the lower side of that is more likely as your splitter placement will be governed by how far apart properties are. 864f cable which is the biggest you'd realistically blow is about 11mm diameter, and costs around £9/metre. If in the PON situation you're blowing say 72f for £1/metre then your costs are honestly not that much higher, considering you don't need to have lots of splitters all over the place (often you have actual passive splitter cabinets, as putting them in chambers is not always possible) you may need a bigger splice joint but not really much bigger because you're now using ribbon fibre. The number of splice operations would be similar too. Obviously this doesn't scale super well, but we are discussing rural subsidised fibre here, not low cost competitive urban deployments. The likelihood is 864f is more than enough for a whole village, or even several. If not add a second.
  - bcrl 3y ago
    Yes, but you don't plan your network based on actual capacity usage, you plan for a fully loaded network that can serve 100% of dwellings passed along with some spare capacity to serve additional buildings over the expected lifespan of the network (30+ years if you're building an expensive incumbent network, 5-10 years if you're trying to minimize cost). Anything else means you could end up turning customers (revenue) away.
deleted 3y ago
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bcrl 3y ago

A 1x32 splitter costs somewhere between $20-70 (unless you pay exorbitant Corning prices). 32 core (well, 36 core) cables are cheap enough, but that's not what you need for a pure point to point network. Let's say you've got a local convergence point with 576 fibres facing the distribution network. With 1x32 splitters you need 18 feeder fibres. You can get a 24 core cable for $350/km. Now, let's say you're building a fully point to point network. You now need a 576 core cable for your feeder in the access network. That's going to cost north of $6000/km (that's a wild guess -- sorry, I don't have accurate numbers for high count cables as I haven't bought any in the past few years). If your access network is 10 km, that's the difference between $3,500 in cables vs $60,000 in cables. Plus you're adding a good $1,500-3,000/km in cost for larger splice closures and increased splicing labour. Where it really hurts is when you start getting close to your Central Office (CO). With P2P networks, you need more larger cables in the first few kilometers closest to the CO, which is often the most congested part of a network. For brownfield builds, that might require directional boring to install new conduit in a town to bring the new cables into the CO. That can get really expensive. Designing fibre networks is a game of whack-a-mole. Spending less on one component drives up costs on other components. Sure a P2P network means you can use cheaper SFPs, but the outside plant is more expensive. There's good reason that most carriers are building Passive Optical Networks -- P2P just isn't economically viable in all scenarios.

matt-p 3y ago
These maths are quite theoretical! In reality in a 1:32 PON you'll typically use somewhere between 14 and 30 ports (because typically you want to leave at least one spare port). In rural areas the lower side of that is more likely as your splitter placement will be governed by how far apart properties are. 864f cable which is the biggest you'd realistically blow is about 11mm diameter, and costs around £9/metre. If in the PON situation you're blowing say 72f for £1/metre then your costs are honestly not that much higher, considering you don't need to have lots of splitters all over the place (often you have actual passive splitter cabinets, as putting them in chambers is not always possible) you may need a bigger splice joint but not really much bigger because you're now using ribbon fibre. The number of splice operations would be similar too. Obviously this doesn't scale super well, but we are discussing rural subsidised fibre here, not low cost competitive urban deployments. The likelihood is 864f is more than enough for a whole village, or even several. If not add a second.
- bcrl 3y ago
  Yes, but you don't plan your network based on actual capacity usage, you plan for a fully loaded network that can serve 100% of dwellings passed along with some spare capacity to serve additional buildings over the expected lifespan of the network (30+ years if you're building an expensive incumbent network, 5-10 years if you're trying to minimize cost). Anything else means you could end up turning customers (revenue) away.

deleted 3y ago

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