Can P2P applications learn to play fair on networks?

Mon Oct 22 06:01:45 UTC 2007

On Sun, 21 Oct 2007, Eric Spaeth wrote:

> They have.   Enter DOCSIS 3.0.   The problem is that the benefits of DOCSIS 
> 3.0 will only come after they've allocated more frequency space, upgraded 
> their CMTS hardware, upgraded their HFC node hardware where necessary, and 
> replaced subscriber modems with DOCSIS 3.0 capable versions.   On an 
> optimistic timeline that's at least 18-24 months before things are going to 
> be better; the problem is things are broken _today_.

Could someone who knows DOCSIS 3.0 (perhaps these are general 
DOCSIS questions) enlighten me (and others?) by responding to a few things 
I have been thinking about.

Let's say cable provider is worried about aggregate upstream capacity for 
each HFC node that might have a few hundred users. Do the modems support 
schemes such as "everybody is guaranteed 128 kilobit/s, if there is 
anything to spare, people can use it but it's marked differently in IP 
PRECEDENCE and treated accordingly to the HFC node", and then carry it 
into the IP aggregation layer, where packets could also be treated 
differently depending on IP PREC.

This is in my mind a much better scheme (guarantee subscribers a certain 
percentage of their total upstream capacity, mark their packets 
differently if they burst above this), as this is general and not protocol 
specific. It could of course also differentiate on packet sizes and a lot 
of other factors. Bad part is that it gives the user an incentive to 
"hack" their CPE to allow them to send higher speed with high priority 
traffic, thus hurting their neighbors.

-- 
Mikael Abrahamsson    email: swmike at swm.pp.se