[e2e] Are we doing sliding window in the Internet?

Lars Eggert lars.eggert at nokia.com
Mon Jan 7 07:11:31 PST 2008

Hi, David,

since your message has me in the "To" field, I'm guessing it was  
triggered by one of my earlier emails.

If that's the case, either I'm not expressing my points clearly  
enough, or you're significantly over-interpreting them. Or both.  
Usually, I'd try to clarify things at this point, but reading the rest  
of your email somehow doesn't leave me with the impression that such  
an attempt would be fruitful.


On 2008-1-7, at 16:46, ext David P. Reed wrote:
> 99% of the effect of the original TCP congestion control  
> "innovation" was due to a simple and robust principle: when a packet  
> is lost, cut the traffic being sent *drastically*.   This converted  
> a tendency of the community to turn packet losses into a positive  
> feedback loop of retransmission into a shared understanding that  
> "positive feedback loops are bad".
> That was a community-scale learning that was useful.
> I would argue that the idea that TCP is now "near perfect" as a  
> standard that *must be enforced lest the Internet enter congestion  
> collapse* has almost no real-world evidence.
> In fact, very little of the traffic on the network today comes in  
> the form of end-to-end unbounded-rate-demanding streams.   TCP's  
> congestion control (and the definition of "TCP compatible" fairness,  
> too!) is "tested" only for such a trivial case.   No One At All  
> tests TCP congestion control in a world of HTTP, VoIP, streaming  
> video from YouTube, Skype, etc. The "gurus" of the IETF that study  
> protocol *documents* have intuitions that are seriously flawed, if  
> only because they don't actually have any data about the traffic  
> ANYWHERE in the damn network.   (kc claffy would die to have such  
> data).
> So it seems that a bunch of self-elected high-priests of IETF have  
> taken it upon themselves to claim God-like, experiment-free  
> knowledge of the Internet as it really is, and to use that knowledge  
> to claim that TCP is the Gold Standard that must be obeyed lest the  
> network finally do what Bob Metcalfe erroneously said it would do  
> and ate whatever piece of clothing he ate as a result.
> Do science and real engineering, please.   Yeah, the AIMD algorithm  
> in TCP saved the Internet's ass.  But it is not Holy Writ.

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