[e2e] TCP Loss Differentiation

Lars Eggert lars.eggert at nokia.com
Mon Feb 23 09:16:42 PST 2009

On 2009-2-23, at 18:01, David P. Reed wrote:
> Is the Internet ecology so broken that good things that are pretty
> simple just cannot be deployed at all?

Yes, pretty much, if they could end up causing a significant number of  
support hotline calls ("Vista broke my router").

There is a bit of hope, because the same slide deck shows that things  
like F-RTO and DSACK were OK to turn on. But they're algorithmic  
changes to the end system stack and don't cause bits to go "1" that  
didn't use to go "1". And the problem isn't only broken NATs, there's  
also often overzealous firewalls that drop packets that have bits set  
by protocol extensions that are newer than the RFC the firewall vendor  
chose to scrub the dataflow against.

> What does that imply for any
> hope at all for a "clean slate" other than omphalocentric research by
> hypercautious academics who will never have an impact (other than
> sucking money from NSF and DARPA)?  :-)

Realizing that we're getting pretty far off topic here, I believe  
clean-slate research to be important in establishing upper bounds on  
what is doable in layer 3/4 internetworking, but I'm not holding my  
breath for actual commercial deployment. Then again, if the benefits  
are convincing enough, maybe people are willing to take the leap.

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