[e2e] opening multiple TCP connections getting popular

David P. Reed dpreed at reed.com
Fri Aug 31 05:33:09 PDT 2007

It's fascinating to me that Window Scaling (an end-to-end option) would 
be screwed by bugs in *routers*.  If literally true about network layer 
routers, what that means is that the whole design of the Internet is now 
beyond modification, since the modularity that modification depends on 
cannot be presumed.

So I'm even more depressed than Michael.

But I'd suggest that there's a third option, one I've advocated 
before.   Use the basic strategy that gave us the Internet again, on top 
of today's broken Internet.  Build a new, properly modularized, fully 
interoperable network layered on top of today's broken Internet.

One would think there were enough stakeholders in doing this that a 
consortium of like-minded people could get critical mass across the 
"users" (end device makers, applicaiton providers, ...).   They nust 
need to agree to support each other like Odysseus was supported when he 
was tied to the mast, blindfolded etc. to avoid the Sirens.

The Sirens in this case are the Ciscos and the transport providers who 
say - don't go away from our "locked-in" unchangeable current products 
and services that run raw IP through hard-microcoded switches and pipes 
and TOEs, etc.  Don't go away because although you can't make the 
Internet better, WE can make it faster.

If you listen to the Sirens, you get a really great dragster experience, 
but cars that can maneuver, adapt to new environments - why would you 
want to evolve pure perfection?

The Internet is indeed the Best of All Possible Worlds.

Michael Welzl wrote:
> On Fri, 2007-08-31 at 11:08 +0900, Lars Eggert wrote:
>> On 2007-8-30, at 15:18, ext Michael Welzl wrote:
>>> Does anybody know if there's a generally known, agreed upon reason
>>> for not using Window Scaling? Google tells me that some broken
>>> routers can't handle it... but, interestingly, Wikipedia (via
>>> google :-) ) tells me that, since kernel version 2.6.8, the option
>>> is enabled in Linux by default, and that it's used (by default? don't
>>> know) in Vista...  so what, are we already heading for trouble?
>> Microsoft presented their findings related to window scaling (and  
>> several other TCP extensions) at the IETF TSVAREA meeting in Prague.  
>> See http://www3.ietf.org/proceedings/07mar/slides/tsvarea-3/sld3.htm  
>> and the two following slides. Summary: Window scaling is enabled in  
>> Vista, but limited to a factor of 2.
>> PPT slides are here: http://www3.ietf.org/proceedings/07mar/slides/ 
>> tsvarea-3/tsvarea-3.ppt
> Thanks, that's very interesting! (and thanks to David Ros too,
> who also pointed me to these slides in a private email)
> So ... the reasons they give are bugs, bugs, bugs.
> I guess this means that we are facing a world where working
> on congestion control is rather pointless because:
> 1) either your personal bottleneck is the limit (and all
>    you care about is that your flows fairly share it,
>    at least within reasonable boundaries), or
> 2) (in Japan, as Jon said, or maybe our future networks
>    or some other special cases) the receiver window is the
>    limit.
> The reason for 2) is the lack of (proper) use of window
> scaling, which is due to bugs in firewalls, routers etc.
> That's pathetic. What can we do about it? Stop worrying about
> CUBIC vs HTCP vs FAST vs WHATEVERTCP, and shut down ICCRG?
> Maybe we should dedicate our time to sending emails to the
> people responsible for these bugs instead of doing research
> on congestion control.
> Wow... I'm normally an optimistic person, but that perspective
> truly depresses me.
> Cheers,
> Michael

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