[e2e] TCP implementations in various OS's

Detlef Bosau detlef.bosau at web.de
Thu May 13 05:28:56 PDT 2010

Lachlan Andrew wrote:
> On 13 May 2010 06:29, Detlef Bosau <detlef.bosau at web.de> wrote:
>> However, can we agree that a good measure to prevent misbehaviour (which
>> _can_ result from a single flow using window scaling while the competitors
>> don't) is to enable window scaling actually on _all_ flows or on _no_ flows?
>> Although this might lead to some moderate level of congestions even in lines
>> with comparably moderate load?
> I don't think that those conditions are necessary.
> Any flow is entitled to send at *less* than their congestion window.
> If they choose to do that by limiting the protocol to a legacy mode
> (no window scaling), that is their prerogative.  Window scaling is an
> approved mechanism for allowing the intended AIMD behaviour of Reno.

However, the AIMD scheme will simply not converge properly, when some 
flows do window scaling while others don't.

Actually, the prerogative of doing no window scaling means that a a flow 
intentionally misses to use its fair share of capacity.

> The fact that a saturated source sends on a link with a source which
> chooses not to use its full window doesn't mean the saturated source
> is "misbehaving".


It was not my intention to call a decent call misbehaving but the greedy 
one :-)

However, VJCC is a distributed algorithm which implicitly assumes a 
compatible implementation or behaviour in all participating nodes to 
work as intended.


Detlef Bosau            Galileistraße 30        70565 Stuttgart
phone: +49 711 5208031  mobile: +49 172 6819937 skype: detlef.bosau     
ICQ: 566129673          detlef.bosau at web.de     http://www.detlef-bosau.de                      

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