From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] ipv4: IP defragmentation must be ECN aware Date: Thu, 06 Jan 2011 11:21:03 -0800 (PST) Message-ID: <20110106.112103.59674935.davem@davemloft.net> References: <1294249261.10633.54.camel@edumazet-laptop> <20110105094830.63a68230@nehalam> <1294249975.10633.74.camel@edumazet-laptop> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: shemminger@vyatta.com, netdev@vger.kernel.org To: eric.dumazet@gmail.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:38472 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751404Ab1AFTUb (ORCPT ); Thu, 6 Jan 2011 14:20:31 -0500 In-Reply-To: <1294249975.10633.74.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet Date: Wed, 05 Jan 2011 18:52:55 +0100 > [PATCH v2] ipv4: IP defragmentation must be ECN aware > > RFC3168 (The Addition of Explicit Congestion Notification to IP) > states : > > 5.3. Fragmentation > > ECN-capable packets MAY have the DF (Don't Fragment) bit set. > Reassembly of a fragmented packet MUST NOT lose indications of > congestion. In other words, if any fragment of an IP packet to be > reassembled has the CE codepoint set, then one of two actions MUST be > taken: > > * Set the CE codepoint on the reassembled packet. However, this > MUST NOT occur if any of the other fragments contributing to > this reassembly carries the Not-ECT codepoint. > > * The packet is dropped, instead of being reassembled, for any > other reason. > > This patch implements this requirement for IPv4, choosing the first > action : > > If one fragment had NO-ECT codepoint > reassembled frame has NO-ECT > ElIf one fragment had CE codepoint > reassembled frame has CE > > Signed-off-by: Eric Dumazet Applied, thanks a lot Eric.