Kevin D Scott wrote:
Does anybody know what the Internet providers are 'saving' this leftover bandwidth for?
As I said in a previous email the asymmetric nature of Internet access is a pain. If p2p traffic was around from day one maybe things would be different. In any case it came later and for most users it is better to move upload bandwidth over to the download side. With that starting point the ADSL and cable modems have both been designed with that in mind. In the cable world you do not have duplex channels so there is not really leftover upload bandwidth. The cable system was also designed for broadcast so almost all the bandwidth has been allocated for broadcasting (i.e. downloading) The upload channels have to be squeezed into the bottom and top of the spectrum which are also noisy.
So basically there is no "leftover" upload bandwidth in the access part of the network.
Of course the backbone of both MTS and Shaw is symmetric but the utilization is hopefully well under 30% so there is lots of leftover bandwidth in both directions. You achieve low latency without QOS by keeping the utilization of the network low. My understanding is that the Internet backbone (i.e. between cities or ISPs) has also quite low utilization(5-10%). Once you have a fibre pipe incremental bandwidth is free. Of course connecting to other ISPs has a cost and is usually bandwidth sensitive so that is often a choke point.
-- Bill