[Sephiroth]

What next? You ask:

In addition to Horizon's analysis, it more or less works like this (but can vary in different parts of the country according to who was the original cable supplier):

1/
A small street cabinet connects either 16 or 32 customers. A larger street cabinet connects 48 or 96. It is passive equipment.

2/
The cable from a cabinet passes along to another cabinet configured as above.

3/
5 or 6 cabinets go to a powered Launch Cabinet and 4 or 5 of these go to an optical node and it's fibre from there to the local hub. The optical node cabinet is active.

4/
In high density population areas, street cabinets may all be of the 48/96 capacity kind.

5/
The optical node originally would have supported only 2 upstream channels and these might have been split between two nodes at the VM end line card. So that's a heck of a lot of users who think they're getting, say 10 meg upstream sharing just 40 meg upstream capacity.

6/
A downstream service group comprises 16 channels, within which a user's bonding group currently has up to 8 downstream channels with c. 400 meg capacity to share across one or two optical nodes. VM are also bonding two upstream channels.

That explains how over utilisation can occur.

For high contention areas, VM should be adding more optical nodes and line cards and CMTS devices at their end to cope with the additional channels allocated. That's what they say they're doing.

7/
The optical node connects via fibre to a line card on a UBR/CMTS at the local hub/local head end. Many optical nodes terminate on a single line card. An individual's downstream and upstream (both shared with other users) terminate on the same line card andin the same Service Group.