From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Heffner Subject: Re: [PATCH] TCP FIN gets dropped prematurely, results in ack storm Date: Tue, 01 May 2007 14:03:04 -0400 Message-ID: <463780D8.2080105@psc.edu> References: <20070501151354.GB1751@kvack.org> <20070501162050.GB21896@2ka.mipt.ru> <20070501164935.GC1751@kvack.org> <20070501174126.GA7577@2ka.mipt.ru> <20070501175340.GD1751@kvack.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Evgeniy Polyakov , David Miller , netdev@vger.kernel.org To: Benjamin LaHaise Return-path: Received: from mailer2.psc.edu ([128.182.66.106]:61350 "EHLO mailer2.psc.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755255AbXEASIN (ORCPT ); Tue, 1 May 2007 14:08:13 -0400 In-Reply-To: <20070501175340.GD1751@kvack.org> Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Benjamin LaHaise wrote: > On Tue, May 01, 2007 at 09:41:28PM +0400, Evgeniy Polyakov wrote: >> Hmm, 2.2 machine in your test seems to behave incorrectly: > > I am aware of that. However, I think that the loss of certain packets and > reordering can result in the same behaviour. What's more, is that this > behaviour can occur in real deployed systems. "Be strict in what you send > and liberal in what you accept." Both systems should be fixed, which is > what I'm trying to do. Actually, you cannot get in this situation by loss or reordering of packets, only be corruption of state on one side. It sends the FIN, which effectively increases the sequence number by one. However, all later segments it sends have an old lower sequence number, which are now out of window. Being liberal in what you accept is good to a point, but sometimes you have to draw the line. -John