Network end users to pull down 2 gigabytes a day, continuously?

Michael.Dillon at Michael.Dillon at
Sun Jan 7 14:34:09 UTC 2007

> > Note that video caching systems like P2P networks can
> > potentially serve video to extremely large numbers of
> > users while consuming reasonably low levels of upstream
> > bandwidth.
> The total bandwidth used is the same though, no escaping
> that, someone pays.

This is not true. Increased bandwidth consumption does 
not necessarily cost money on most ISP infrastructure. 
At my home I have a fairly typical ISP service using 
BT's DSL. If I use a P2P network to download files from
other BT DSL users, then it doesn't cost me a penny
more than the basic DSL service. It also doesn't cost
BT any more and it doesn't cost those users any more.
The only time that costs increase is when I download
data from outside of BT's network because the increased
traffic reaquires larger circuits or more circuits, etc.

The real problem with P2P networks is that they don't 
generally make download decisions based on network
architecture. This is not inherent in the concept of
P2P which means that it can be changed. It is perfectly
possible to use existing P2P protocols in a way that is
kind to an ISP's costs.

> If it was only redistributed locally. Even in that case it's not
> helping much as it still consumes the most expensive bandwidth (for UK
> ADSL). Transit is way cheaper than BT ADSL wholesale, you're saving
> something that's cheap.

I have to admit that I have no idea how BT charges
ISPs for wholesale ADSL. If there is indeed some kind
of metered charging then Internet video will be a big
problem for the business model. 

> Or the caches that are being sold to fudge the protocols to
> keep it local but if you're buying them we could have just
> as easily done http download and let it be cached by existing
> appliances.

The difference with P2P is that caching is built-in to
the model, therefore 100% of users participate in 
caching. With HTTP, caches are far from universal, 
especially to non-business users.

--Michael Dillon

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