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

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Message-ID: <1345726185.5904.835.camel@edumazet-glaptop>
Date:	Thu, 23 Aug 2012 14:49:45 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alex Bergmann <alex@...lab.net>
Cc:	"H.K. Jerry Chu" <hkjerry.chu@...il.com>, davem@...emloft.net,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] tcp: Wrong timeout for SYN segments

On Thu, 2012-08-23 at 14:37 +0200, Alex Bergmann wrote:

> 
> From be551f82499112e4775b6d579d58967510b6d492 Mon Sep 17 00:00:00 2001
> From: Alexander Bergmann <alex@...lab.net>
> Date: Thu, 23 Aug 2012 14:33:35 +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.[1]
> 
> This patch increases the value of TCP_SYN_RETRIES to the value of 6,
> providing a retransmission window of 63secs.
> 
> [1] RFC 1122 - 4.2.3.5 TCP Connection Failures
> 
> Signed-off-by: Alexander Bergmann <alex@...lab.net>
> ---
>  include/net/tcp.h |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/include/net/tcp.h b/include/net/tcp.h
> index 1f000ff..f309e93 100644
> --- a/include/net/tcp.h
> +++ b/include/net/tcp.h
> @@ -98,7 +98,7 @@ extern void tcp_time_wait(struct sock *sk, int state, int timeo);
>                                  * 15 is ~13-30min depending on RTO.
>                                  */
>  
> -#define TCP_SYN_RETRIES         5      /* number of times to retry active opening a
> +#define TCP_SYN_RETRIES         6      /* number of times to retry active opening a
>                                  * connection: ~180sec is RFC minimum   */
>  
>  #define TCP_SYNACK_RETRIES 5   /* number of times to retry passive opening a

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

A change of the comment might be good, to help future readers.



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