Can P2P applications learn to play fair on networks?

Sun Oct 21 16:23:09 UTC 2007

On Sun, 21 Oct 2007, Sean Donelan wrote:

> Sandvine, packeteer, etc boxes aren't cheap either.  The problem is 
> giving P2P more resources just means P2P consumes more resources, it 
> doesn't solve the problem of sharing those resources with other users. 
> Only if P2P shared network resources with other applications well does 
> increasing network resources make more sense.

If your network cannot handle the traffic, don't offer the services.

It all boils down to the fact that the only thing that end users really 
have to give us as ISPs, is their source address (which we usually assign 
to them), the destination address of the packet they want transported, and 
we can implicitly look at the size of the packet and get that information. 
That's the ONLY thing they have to give us. Forget looking at L4 or alike, 
that will be encrypted as soon as ISPs start to discriminate on it. Users 
have enough computing power available to encrypt everything.

So any device that looks inside packets to decide what to do with them is 
going to fail in the long run and is thus a stop-gap measure before you 
can figure out anything better.

Next step for these devices is to start doing statistical analysis of 
traffic to find patterns, such as "you're sending traffic to hundreds of 
different IPs simultaneously, you must be filesharing" or alike. This is 
the next step and a lot of the box manufacturers are already looking into 
this. So, trench war again, I can see countermeasures to this also.

The long term solution is of course to make sure that you can handle the 
traffic that the customer wants to send (because that's what they can 
control), perhaps by charging for it by some scheme that involves not 
offering flat-fee.

Saying "p2p doesn't play nice with the rest of the network" and blaming 
p2p, only means you're congesting due to insufficient resources, and the 
fact that p2p uses a lot of simultaneous TCP sessions and individually 
they're playing nice, but together they're not when compared to web 
surfing.

The solution is not to try to change p2p, the solution is to fix 
the network or the business model so your network is not congesting.

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