[RndTbl] RE: Roundtable Digest, Vol 23, Issue 14

[Bill Reid]

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