If you have contracted one 1 Gbps rate at home, you will have seen that, when doing a speed test on a computer connected by Ethernet, you do not reach 1,000 Mbps, but remains in figures around the 940 Mbps. With 10 Gbps fiber the difference is even greater, since Digi and Orange have shown in the tests of this connection that the maximum download speed stays around 8 or 8.5 Gbps.
940 Mbps, or 8 Gbps: the limit of Ethernet ports
With ADSL, the “up” was essential because with copper power was lost as the distance increased. This difference in attenuation made the final speed that reached the user different if he lived 300 meters or 1.5 km from the central. However, with fiber, by going all by FTTH, the speed that arrives is the contracted one.
Or at least it should be. If there are people who reach 8 Gbps when they hire 10 Gbps thanks to the XGS-PON standard, why don’t we get 1 Gbps exactly when we hire that speed, and stay at 940 Mbps? The key lies in the way we connect to the router, since the main limiting factor is the Ethernet cable.
The RJ45 port of most fiber routers is Gigabit, where it is capable of reaching 1 Gbps of speed on paper. However, this speed is not reached because the cable needs a reserved space for him encapsulation of Ethernet frames, where a margin known as overhead, or extra cost, for guarantee the delivery of the data. Therefore, you will never be able to exceed that speed with a Gigabit Ethernet cable. It is different if we use a port 2.5G Ethernet, or even one of 10 Gbps, for a 1 Gbps connection.
The WiFi allows you to get the whole game at 1 Gbps
This limit has been overcome even with routers with WiFi 6. It is quite common to already find WiFi 6 routers that reach speeds of 3 or 6 Gbps wirelessly, or at least they can reach it theoretically. However, GPON routers have the limit in the SFP transceiver, so that we cannot reach more than 1 Gbps wirelessly. With an XGS-PON router without that limit, it is currently possible to reach 1.5 Gbps.
While with the Gigabit networks a loss of just 50 or 60 Mbps is not too much, with a 10 Gbps network we do lose 1.5 or 2 Gbps of speed. Two factors come into play here.
The first is that there is also overhead, but it is less, standing at about 200 Mbps. Thus, in a port 10 GbE Ethernet, we can reach figures of up to 9.8 Gbps. However, why does a speed test on a 10 Gbps connection leave us at only 8 Gbps?
This is where the second reason comes in, and that is that operators sacrifice speed in exchange for stability vis-à-vis customers, and they use that extra bandwidth for error correction in the event of attenuation. The maximum speed of XGS-PON could reach 9,953.28 Mbps, but adding the error correction, the speed is much more limited, reaching up to 8.5 Gbps which Orange showed for example at the XGS-PON presentation.
It is possible to obtain higher speeds using the so-called Jumbo Frames, that is, frames of more than 1,500 bytes that are used in default Ethernet connectivity. With 1,500 bytes it is possible to achieve up to 9.4 Gbps, but with 9,000 byte frames, it is possible to reach up to 9.8 Gbps.
In short, we are facing a perfect example of first world problem, where it is a blessing to be able to navigate at speeds of 300, 600 or 1,000 Mbps, and very soon 10 Gbps in large Spanish cities. And much more at the prices that fiber currently has with the crazy offers that the big operators have taken out.