The Natural Philosopher wrote:

wrote:

The kind of fibre service that BT are offering is unfortunately not
at all symmetric. The uplink is time division multiplexed in the
same sort of way that cable services operate.

I dont think so.
No on uses TDM these days - its all packet switched

He's right ...

Everyone is sharing a single fibre at the exchange-end, one downstream
wavelength gives 2.48 Mbps, a different wavelength gives 1.24 Mbps
upstream, closer to the premises it gets passively optically split for
up to 32 sub-fibres to the premises.

All downstream packets arrive at all premises and the ONT filters out
everyone's but yours, there are timeslots that you get to transmit on
the upstream wavelength to fit your traffic around everyone else's.

Packet switched over 21CN once it gets back to the exchange.

G.984 if you're bored ...