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

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Message-Id: <20120831.154234.735439593093335863.davem@davemloft.net>
Date:	Fri, 31 Aug 2012 15:42:34 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	alex@...lab.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

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Fri, 31 Aug 2012 06:25:50 -0700

> 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>

Applied with some minor comment formatting and wording adjustments.

Thanks everyone.
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