netdev - Re: [PATCH 1/1] tcp: Wrong timeout for SYN segments

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Date:	Fri, 31 Aug 2012 06:25:50 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alexander Bergmann <alex@...lab.net>
Cc:	davem@...emloft.net, hkjerry.chu@...il.com, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] tcp: Wrong timeout for SYN segments

On Fri, 2012-08-31 at 14:48 +0200, Alexander Bergmann wrote:

> Hi Eric!
> 
> I've also changed the Documentation file. As usual, comments are welcome!
> 
> 
> Alex
> 
> 
> From 848f34ce27f65401940ae98e0b2d395888d3986d Mon Sep 17 00:00:00 2001
> From: Alexander Bergmann <alex@...lab.net>
> Date: Fri, 31 Aug 2012 14:31:00 +0200
> Subject: [PATCH 1/1] tcp: Increase timeout for SYN segments
> 
> Commit 9ad7c049 changed the initRTO from 3secs to 1sec in accordance to
> RFC6298 (former RFC2988bis). This reduced the time till the last SYN
> retransmission packet gets sent from 93secs to 31secs.
> 
> RFC1122 is stating that the retransmission should be done for at least 3
> minutes, but this seems to be quite high.
> 
>   "However, the values of R1 and R2 may be different for SYN
>   and data segments.  In particular, R2 for a SYN segment MUST
>   be set large enough to provide retransmission of the segment
>   for at least 3 minutes.  The application can close the
>   connection (i.e., give up on the open attempt) sooner, of
>   course."
> 
> This patch increases the value of TCP_SYN_RETRIES to the value of 6,
> providing a retransmission window of 63secs.
> 
> The comments for SYN and SYNACK retries have also been updated to
> describe the current settings. The same goes for the documentation file
> "Documentation/networking/ip-sysctl.txt".
> 
> Signed-off-by: Alexander Bergmann <alex@...lab.net>
> ---

Thanks for your patience and followup, this seems good to me !

Acked-by: Eric Dumazet <edumazet@...gle.com>



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