netdev - Re: [PATCH RFC] Allow to turn off TCP window scale opt per route

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Message-ID: <4ADEC3EE.2070301@codefidence.com>
Date:	Wed, 21 Oct 2009 10:18:54 +0200
From:	Gilad Ben-Yossef <gilad@...efidence.com>
To:	Stephen Hemminger <shemminger@...tta.com>
CC:	netdev@...r.kernel.org, ori@...sleep.com
Subject: Re: [PATCH RFC] Allow to turn off TCP window scale opt per route

Stephen Hemminger wrote:

> On Tue, 20 Oct 2009 17:22:39 +0200
> Gilad Ben-Yossef <gilad@...efidence.com> wrote:
>
>   
>> Add and use no window scale bit in the features field.
>>
>> Signed-off-by: Gilad Ben-Yossef <gilad@...efidence.com>
>> Sigend-off-by: Ori Finkelman <ori@...sleep.com>
>> Sigend-off-by: Yony Amit <yony@...sleep.com>
>>     
>
> The same effect can by just using window limit on route
>   
Actually, not exactly. There is a subtle but important difference 
between "I support window scaling, but choose a scale of 0", which is 
what your suggestion will imply and "I don't support window scaling at 
all", which is what the suggested feature field does.

To make things more complicated, until the previous patch I sent, when 
Linux would choose a window scale of zero for any reason, it would also 
wrongfully report it does not support window scaling at all to the other 
side, with some subtle bug caused by it, but this is no longer the 
behavior and I believe rightly so.

Thanks,
Gilad

-- 
Gilad Ben-Yossef
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