North American Network Operators Group

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

  • From: Marshall Eubanks
  • Date: Tue Oct 23 09:08:11 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