On 27/08/2013 09:24, The Natural Philosopher wrote:
On 27/08/13 08:38, dennis@home wrote:
On 26/08/2013 22:44, Tim Streater wrote:

Its done at the IP layer.
The customers ATM circuit does not get as far as the ISP on the ADSL
services.

Whose idea was this, then, and why.


No idea, to hide the underlying architecture from the service they
sell I would think.

The ATM does get to the ISP from the customer.

You wouldn't want the ISP to have ATM to the customer as that would
allow them to offer QOS.


At some level BT provide that for them.


It doesn't do any such thing.
Not for normal retail ISPs.

It sells the ISP a pipe and the other side of the pipe has a certain
contention ratio depending on how much the ISP is paying. That
contention is for all ISPs using that bit of the network.

Its up to the ISP what contention ratio they put on their pipe into the
network as long as they don't put more customers on than they are paying
for.

There is no QOS offered on the product.