[e2e] Historical question: Link layer flow control / silent discard

Detlef Bosau detlef.bosau at web.de
Sun May 26 23:22:55 PDT 2013

Am 26.05.2013 18:50, schrieb Matt Mathis:
> On Sat, May 25, 2013 at 4:34 PM, Lachlan Andrew <lachlan.andrew at gmail.com>wrote:
>> I've always wondered why
>> switched ethernet (which does the ISO layer-3 tasks of addressing,
>> routing over multiple point-to-point links and buffering) is called a
>> "link layer" by the internet community...
> It's called "feature creep".  Ethernet 2.0 (predates 802.*) was clearly a
> link layer.  IEEE keeps adding stuff.  Many Internet purists complained.
>   We now are paying for doing nearly everything twice: once in silicon by
> way of the IEEE and once in the Internet proper.   As far as the internet
> is concerned, the extra complexity in the lower layer is mostly a waste.
I wouldn't talk about feature creep.

Actually, we're talking about the good old end to end discussion: Where 
are things to be done?

A prominent example is the embarrassing BIC/CUBIC discussion. When there 
is a "long fat link" along the path, why do we need any kind of 
"estimation" to use, to even detect it? Hence: Why are the end points 
responsible to "estimate" a proper congestion window? When at the same 
time the network operator knows about the LFN link and we can a, 
sometimes helpless, sometimes educated guess by sound knowledge?

And why is scheduling of TCP flows left to a self scheduling mechanism, 
which may have some scalability issues and some memory issues, as we 
discussed and agreed some weeks ago, when we have working scheduling 

I'm still not convinced that we're doing the right things at the right 
places here!

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