[e2e] Skype and congestion collapse.

[Cannara]

I'll 2nd this and just add that corporate folks do like P2P for their own
purposes, such as providing multiple external sources for downloading
presentations & docs to field staff & customers quickly, anywhere.  It's a
wave that's not going to die down.  Questioably-legal P2P uses, however, will
become more & more monitored & controlled.

Alex


Richard Wade wrote:
> 
> "DJamel H. Sadok" <jamel at cin.ufpe.br> wrote:
> > IMHO, it does not anymore make a lot of sense to penalyze "low" bandwidth
> > applications such as skype/voip/.. by applying TCP-like congestion control
> > or access control schemes. Such mechanisms are better used on heavy
> > hitters such as some P2P multimedia transfers.
> 
> But how many mice does it take to bring down an elephant?
> This area has been examined quite extensively. A quick Web search revealed:
> 
> http://www.ieee-infocom.org/2004/Papers/58_2.PDF "Using Partial
> Differential Equations to Model TCP Mice and Elephants in Large IP
> Networks"
> 
> or for a different view of the problem:
> 
> http://www.caida.org/outreach/papers/2002/Dragonflies/cnit.pdf
> "Understanding Internet Traffic Streams: Dragonflies and Tortoises"
> 
> >From a practical IP networking perspective, the "big hitters" are actually
> quite easy to deal with. If you've got a flow that's long in duration
> (minutes, hours, or days) then policy can be applied at the edge of your
> network to shape or control it. Many people are having to deploy P2P
> control systems in their networks due to the huge increase in this type of
> application over the past few years.
> 
> In the late 1990s, people deployed huge arrays of HTTP proxies in order to
> save on expensive off-net bandwidth. The effectiveness of this slowly
> decreased as more and more dynamic content was served up. P2P is just the
> latest application type that is consuming the majority of off-net transit
> for service providers. Yes, bandwidth costs are much lower than in the
> late 1990s, but you still want to minimise the cost, right?
> 
> You can deploy P2P caches on-net, but some people seem to be shying away
> from deploying them, citing "legal reasons". I'm not quite sure what the
> difference is between a P2P cache and a HTTP cache in this respect,
> however. Alternatively, you can use protocol re-write engines, such as the
> Packeteer, which can sit in-line and shape the flows down to specified
> rates. Or you can try to just queue and shape the application's traffic at
> your edge routers.
> 
> > We need traffic to justify giga-networks hopefully all the way to the
> > local loop. There has been a great deal of work on protocol adaptation and
> > congestion control with little actual use.
> 
> I would actually argue that we need the applications to justify
> giga-networks, not just "traffic". What actually _are_ the killer
> applications for high bandwidth consumer access? VoIP? - low bandwidth;
> Web? - low bandwidth and non-realtime; etc. So we're currently left with
> P2P file transfer which, among its many legitimate uses, is generally used
> to illegally distribute copyright material. Not quite the ideal "killer
> application".
> 
> Arguably, many providers are building high bandwidth access (and core)
> networks to support next-generation services which aren't quite here yet.
> Before these services can be deployed and the networks can be engineered
> in to a state that permits more fine-grained traffic control, applications
> such as Skype will have to deal with this type of situation.
> --
> rik