On Wed, 12 Aug 2020 07:44:31 +0100, The Natural Philosopher wrote:

The kind of fibre service that BT are offering is unfortunately
not
at all symmetric.Â* 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.

Or even up to 64 but that starts to limit the range to less than 10
km on a subs fibre. B-)

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.

no.
Not according to what wiki says. Its all wavelength division.

Wavelength for the up/down combined streams.
Time for individual connections within those streams.

Are we also being sold a pup again with "1 Gbps capable" connections?
If the down stream is limited to 2.48 G bps and all 32 customers are
trying to fill their pipe surely all they'll get is 2.48/32 ~ 78 Mbps
throughput even if individual packets are signalled at 2.48 Gbps.

--
Cheers
Dave.