netdev - Re: [PATCH] TCP FIN gets dropped prematurely, results in ack storm

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Message-ID: <20070501164935.GC1751@kvack.org>
Date:	Tue, 1 May 2007 12:49:35 -0400
From:	Benjamin LaHaise <bcrl@...ck.org>
To:	Evgeniy Polyakov <johnpol@....mipt.ru>
Cc:	David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Subject: Re: [PATCH] TCP FIN gets dropped prematurely, results in ack storm

On Tue, May 01, 2007 at 08:20:50PM +0400, Evgeniy Polyakov wrote:
> > http://www.kvack.org/~bcrl/ack-storm.log .  As near as I can tell, a 
> > similar effect can occur between two Linux boxes if the right packets get 
> > reordered/dropped during connection teardown.
> 
> Could you archive 24Mb file or cut more precise bits out of it?

The interesting bits are the first 10 lines.

> According to your patch, several packets with fin bit might be sent,
> including one with data. If another host does not receive fin
> retransmit, then that logic is broken, and it can not be fixed by
> duplicating fins, I would even say, that remote box should drop second
> packet with fin, while it can carry data, which will break higher
> connection logic.

The FIN hasn't been ack'd by the other side, though and yet Linux is no 
longer transmitting packets with it sent.  Read the beginning of the trace.

		-ben
-- 
"Time is of no importance, Mr. President, only life is important."
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