[e2e] TCP implementations in various OS's

[Detlef Bosau]

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


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