G.fast is a new technology that can deliver headlines rates of over 100 Mbit/s by using higher frequencies over the access infrastructure than previously available.
Functionally it’s an enhancement to the well-established FTTC (Fibre To The Cabinet) product. Like existing FTTC G.Fast provides a high speed broadband Internet connection to the customer premises by using Optical fibre to the cabinet in the street and then normal copper telephone wiring to the customer premises. Where existing FTTC used a standard called VDSL2 to deliver speeds of up to 80Mbps over the phone line , G.Fast is a new standard that replaces VDSL2 and offers speeds up to 330Mbps over the same copper phone line. As with existing FTTC G.Fast requires that the end user maintain the working phone line for the life of the service.
Just like ADSL2+ and FTTC broadband the maximum speed achieved will be limited by the length of the customers phone line between the customer premises and the street cabinet that serves the premises, but trials have revealed unparalleled speeds . There is no faster technology available today for delivering broadband over copper phone lines. G.Fast works at distances of up to about 300m between the customer and premises. BT will only allow an order to be placed where the availability checker states that the predicted speed is 80.01Mbps or higher.
Currently in trial BT Openreach visit each customer premises to install the service. Currently the service can only be installed at the customer phone line’s master socket. The Openreach engineer will replace the faceplate on the master socket for a new one that has both a standard BT socket and an RJ11 socket to connect a modem.
During the trial BT are providing the modem. Unlike existing FTTC there are currently no 3rd party G.Fast Modem/Routers available.
The BT modem has a DSL port which connects to the BT master socket, Power for the supplied adaptor, and a customer facing Ethernet socket.
The customer should connect their own router to the yellow Ethernet socket. The customer’s router is then configured to talk industry standard PPPoE using the details provided by Cerberus. No other configuration details are required as these are hard coded into the BT Modem.
As the G.Fast service is very fast customers must ensure that their router is rated for the throughput of the service that they order and has a Gigabit Ethernet WAN port (1000Mbps / 1Gbps). Some cheaper routers designed for older FTTC only have a 100MBps port, and so cannot go any faster. If used with the 160Mbps or 330Mbps G.Fast service your speed will be limited to a maximum of 100Mbps.
In the early days of FTTC this was also engineer-installed with a BT provided Modem. G.Fast is pretty much the identical experience. Like FTTC, it is expected that in time self-install options will be available using 3rd party modem/routers and plugin microfilters and will not require a BT Openreach visit.