From: Mark McKinstry Subject: [PATCH] vti6: Add pmtu handling to vti6_xmit. Date: Wed, 10 Feb 2016 01:50:20 +0000 Message-ID: <56BA975D.2040706@alliedtelesis.co.nz> References: <20150529182709.2147.78230.stgit@ahduyck-vm-fedora22> Mime-Version: 1.0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: 8BIT Cc: "alexander.h.duyck@redhat.com" , "herbert@gondor.apana.org.au" , "steffen.klassert@secunet.com" , "davem@davemloft.net" To: "linux-crypto@vger.kernel.org" Return-path: Received: from gate2.alliedtelesis.co.nz ([202.36.163.20]:37647 "EHLO gate2.alliedtelesis.co.nz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755406AbcBJBuf convert rfc822-to-8bit (ORCPT ); Tue, 9 Feb 2016 20:50:35 -0500 Received: from mmarshal3.atlnz.lc (mmarshal3.atlnz.lc [10.32.18.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by gate2.alliedtelesis.co.nz (Postfix) with ESMTPS id E1FE4806CB for ; Wed, 10 Feb 2016 14:50:28 +1300 (NZDT) In-Reply-To: <20150529182709.2147.78230.stgit@ahduyck-vm-fedora22> Content-Language: en-US Content-ID: Sender: linux-crypto-owner@vger.kernel.org List-ID: http://www.spinics.net/lists/linux-crypto/msg15101.html > From: Steffen Klassert > > We currently rely on the PMTU discovery of xfrm. > However if a packet is localy sent, the PMTU mechanism > of xfrm tries to to local socket notification what > might not work for applications like ping that don't > check for this. So add pmtu handling to vti6_xmit to > report MTU changes immediately. > > Signed-off-by: Steffen Klassert > Signed-off-by: Alexander Duyck > --- > > So this version is slightly modified to cover the IPv4 case in addition to > the IPv6 case. With this patch I was able to run netperf over either an > IPv4 or IPv6 address routed over the ip6_vti tunnel. We have the same issue. When we do a local ping to a remote device over a v4 vti tunnel and an intermediate device has a low mtu, pmtu discovery reduces the route's pmtu, and ping fails because it does not handle the local error message generated by xfrm4_tunnel_check_size(). Your patch fixes our issue for v6 vti tunnels, but the issue still exists for v4 tunnels. Is there any particular reason this patch was not delivered for v4 tunnels too - i.e. in vti_xmit()?