From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] sit: allow ip fragmentation when using nopmtudisc to fix package loss Date: Fri, 28 Aug 2009 23:54:04 -0700 (PDT) Message-ID: <20090828.235404.61171174.davem@davemloft.net> References: <1251197322-3177-1-git-send-email-contact@saschahlusiak.de> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: contact@saschahlusiak.de Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:36235 "EHLO sunset.davemloft.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751083AbZH2Gxu (ORCPT ); Sat, 29 Aug 2009 02:53:50 -0400 In-Reply-To: <1251197322-3177-1-git-send-email-contact@saschahlusiak.de> Sender: netdev-owner@vger.kernel.org List-ID: From: Sascha Hlusiak Date: Tue, 25 Aug 2009 12:48:42 +0200 > if tunnel parameters have frag_off set to IP_DF, pmtudisc on the ipv4 link > will be performed by deriving the mtu from the ipv4 link and setting the > DF-Flag of the encapsulating IPv4 Header. If fragmentation is needed on the > way, the IPv4 pmtu gets adjusted, the ipv6 package will be resent eventually, > using the new and lower mtu and everyone is happy. > > If the frag_off parameter is unset, the mtu for the tunnel will be derived > from the tunnel device or the ipv6 pmtu, which might be higher than the ipv4 > pmtu. In that case we must allow the fragmentation of the IPv4 packet because > the IPv6 mtu wouldn't 'learn' from the adjusted IPv4 pmtu, resulting in > frequent icmp_frag_needed and package loss on the IPv6 layer. > > This patch allows fragmentation when tunnel was created with parameter > nopmtudisc, like in ipip/gre tunnels. > > Signed-off-by: Sascha Hlusiak Seems reasonable, applied to net-next-2.6, thanks!