Re: Can P2P applications learn to play fair on networks?

[Sean Donelan <sean () donelan com>]

On Fri, 26 Oct 2007, Joe Greco wrote:
> So, what happens when you add sufficient capacity to the packet switch
> network that it is able to deliver committed bandwidth to all users?
>
> Answer: by adding capacity, you've created a packet switched network where
> you actually get dedicated capacity for your sole use.

Changing the capacity at different points in the network merely moves
the congestion points around the network.  There will still be congestion
points in any packet network.

The problem is not bandwidth, its shared congestion points.

Don't share congestion points: bandwidth irrelevant.
Shared congestion points: bandwidth irrelevant.

A 56Kbps network with no shared congestion points: not a problem
A 1,000 Terabit network with shared congestion points: a problem

The difference is if there is shared congestion points, not the 
bandwidth.

If you think adjusting capacity is the solution, and hosts don't 
voluntarily adjust their demand on their own, then you should be 
*REDUCING* your access capacity which will move the congestion point 
closer to the host.

However, I think a better idea instead of trying to eliminate all shared 
congestion points everywhere in a packet network would be for the TCP 
protocol magicians to develop a TCP-multi-flow congestion avoidance which 
would share the available capacity better between all of the demand at
the various shared congestion points in the network.

Isn't the Internet supposed be a "dumb" network with "smart" hosts?  If 
the hosts act dumb, is the network forced to act smart?