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Yes, GPON is overprovisioned (at 1:32 for Openreach). However, that isn't the full explanation for mediocre upload speeds on Openreach. GPON has a total shared

by orra 3y ago

Yes, GPON is overprovisioned (at 1:32 for Openreach). However, that isn't the full explanation for mediocre upload speeds on Openreach. GPON has a total shared capacity of 2.4 Gbps down and 1.2 Gbps. So you'd think if 1 Gbps down is possible, 500 Mbps up would be. Simply, Openreach probably have mediocre upload speeds on FTTP, so they can protect their leased line profit margins. CityFibre use GPON, the exact same technology as Openreach. Yes, CityFibre offer a nice symmetric service on top of that, because real world contention is usually much lower than the theoretical maximum. It's also worth noting CityFibre are starting to upgrade to XGS-PON.

flumpcakes 3y ago
> GPON has a total shared capacity of 2.4 Gbps down and 1.2 Gbps. So you'd think if 1 Gbps down is possible, 500 Mbps up would be. The "download" direction is sent to you and all your neighbours and only you can access the information as it is AES encrypted to your terminal (CPE, etc.). So you could get 2.4Gbps down, as long as your neighbours are not using it. 1.2Gbps "upload" direction is time shared, so you will never get the full 1.2Gpbs unless you have literally zero neighbours / other terminals on the optical bundle.
- orra 3y ago
  Dynamic Bandwidth Allocation (DBA) fixes the TDM limited upload that you describe. https://www.lightwaveonline.com/fttx/pon-systems/article/16649607/dynamic-bandwidth-allocation-sets-gpons-apart https://www.lightwaveonline.com/fttx/pon-systems/article/166... Again, CityFibre is not Point to Point fibre. They offer 1Gbps upload on GPON, contended at 1:32. From the horse's mouth: https://cdn.cityfibre.com/Partner-page/Downloads/CF-FTTH-Local.pdf https://cdn.cityfibre.com/Partner-page/Downloads/CF-FTTH-Loc... Even Openreach have a 220Mbit/s upload tier, but it costs more than twice as much so nobody offers it for home users. https://www.openreach.co.uk/orpg/home/products/pricing/loadProductPriceDetails.do?data=SjLGnN8O1mzybN7g39pZiNKvrleClYZjBLZ4w%2FibaalZ6rNZujnCs99NbIKJZPD9hXYmiijxH6wrCQm97GZMyQ%3D%3D https://www.openreach.co.uk/orpg/home/products/pricing/loadP...

by orra 3y ago

flumpcakes 3y ago

> GPON has a total shared capacity of 2.4 Gbps down and 1.2 Gbps. So you'd think if 1 Gbps down is possible, 500 Mbps up would be. The "download" direction is sent to you and all your neighbours and only you can access the information as it is AES encrypted to your terminal (CPE, etc.). So you could get 2.4Gbps down, as long as your neighbours are not using it. 1.2Gbps "upload" direction is time shared, so you will never get the full 1.2Gpbs unless you have literally zero neighbours / other terminals on the optical bundle.

orra 3y ago
Dynamic Bandwidth Allocation (DBA) fixes the TDM limited upload that you describe. https://www.lightwaveonline.com/fttx/pon-systems/article/16649607/dynamic-bandwidth-allocation-sets-gpons-apart https://www.lightwaveonline.com/fttx/pon-systems/article/166... Again, CityFibre is not Point to Point fibre. They offer 1Gbps upload on GPON, contended at 1:32. From the horse's mouth: https://cdn.cityfibre.com/Partner-page/Downloads/CF-FTTH-Local.pdf https://cdn.cityfibre.com/Partner-page/Downloads/CF-FTTH-Loc... Even Openreach have a 220Mbit/s upload tier, but it costs more than twice as much so nobody offers it for home users. https://www.openreach.co.uk/orpg/home/products/pricing/loadProductPriceDetails.do?data=SjLGnN8O1mzybN7g39pZiNKvrleClYZjBLZ4w%2FibaalZ6rNZujnCs99NbIKJZPD9hXYmiijxH6wrCQm97GZMyQ%3D%3D https://www.openreach.co.uk/orpg/home/products/pricing/loadP...