[e2e] Skype and congestion collapse.

[Clark Gaylord]

Alex Cannara wrote:

> Syed, the misconception is that apps are to manage network resources.  
> That's not how more robust systems, like the established telco and 
> private network systems work.  Systems must protect themselves, even a 
> car's gearbox, from external abuse.  The Internet is only different in 
> that attention wasn't paid to doing that in its design.

But that doesn't mean that we can't pay more attention to it now.  
Gearboxes didn't protect themselves originally either, but synchromesh 
and fluid drive have done a lot to address that.  The advances in 
computing are due to algorithms, and in recent years that has been 
parallel algorithms.  That's what TCP is: a distributed, parallel 
algorithm that does a reasonable job of equitably sharing limited 
resources.  But you are correct that our network systems can do more to 
enforce fairness and compliance at some level.

By protecting TCP traffic from non-TCP-friendly traffic, by ensuring 
that TCP plays by the rules, by judiciously and scalably employing 
policing and differential queueing -- we can build a much better 
system.  But what makes the Internet a superior *engineering* solution 
is that it doesn't try to over-specify everything.  "Do just enough" is 
what makes this work, and it isn't due to laziness: it is due to the 
inherently superior scalability of this approach.  We don't need to 
debate whether the Internet is a superior solution to the PSTN; reality 
has already proven that.  What is left is for those of us who wistfully 
harken to when TDM was king and everyone had a 3270 to understand that 
we need to crack our bell-shaped heads open and get up to date.  Poisson 
and Erlang don't apply anymore, but doesn't mean we can't model (or that 
we can't extend them in interesting ways, btw).  Call admission doesn't 
apply anymore, but that doesn't mean we have to drop all packets equally.

"What do we need to do to make the Internet better?" is the question we 
need to be asking.

--ckg