Can P2P applications learn to play fair on networks?

Tue Oct 23 12:52:26 UTC 2007

On Oct 23, 2007, at 7:18 AM, Iljitsch van Beijnum wrote:

>
> On 22-okt-2007, at 18:12, Sean Donelan wrote:
>
>> Network operators probably aren't operating from altruistic  
>> principles, but for most network operators when the pain isn't  
>> spread equally across the the customer base it represents a  
>> "fairness" issue.  If 490 customers are complaining about bad  
>> network performance and the cause is traced to what 10 customers  
>> are doing, the reaction is to hammer the nails sticking out.
>
> The problem here is that they seem to be using a sledge hammer:  
> BitTorrent is essentially left dead in the water. And they deny  
> doing anything, to boot.
>
> A reasonable approach would be to throttle the offending  
> applications to make them fit inside the maximum reasonable traffic  
> envelope.
>
> What I would like is a system where there are two diffserv traffic  
> classes: normal and scavenger-like. When a user trips some  
> predefined traffic limit within a certain period, all their traffic  
> is put in the scavenger bucket which takes a back seat to normal  
> traffic. P2P users can then voluntarily choose to classify their  
> traffic in the lower service class where it doesn't get in the way  
> of interactive applications (both theirs and their neighbor's). I  
> believe Azureus can already do this today. It would even be  
> somewhat reasonable to require heavy users to buy a new modem that  
> can implement this.

I also would like to see a UDP scavenger service, for those  
applications that generate lots of bits but
can tolerate fairly high packet losses without replacement. (VLBI,  
for example, can in principle live with 10% packet loss without much  
pain.)

  Drop it if you need too, if you have the resources let it through.  
Congestion control is not an issue because, if there is congestion,  
it gets dropped.

In this case, I suspect that a "worst effort" TOS class would be  
honored across domains. I also suspect that BitTorrent could live  
with this TOS quite nicely.

Regards
Marshall