From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net-next v4] ip6_vti: adjust vti mtu according to mtu of lower device Date: Wed, 20 Dec 2017 11:53:08 -0500 (EST) Message-ID: <20171220.115308.830476038264270823.davem@davemloft.net> References: <1513691961-19692-1-git-send-email-alexey.kodanev@oracle.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, steffen.klassert@secunet.com, pvorel@suse.cz, shannon.nelson@oracle.com To: alexey.kodanev@oracle.com Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:40322 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755147AbdLTQxL (ORCPT ); Wed, 20 Dec 2017 11:53:11 -0500 In-Reply-To: <1513691961-19692-1-git-send-email-alexey.kodanev@oracle.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Alexey Kodanev Date: Tue, 19 Dec 2017 16:59:21 +0300 > LTP/udp6_ipsec_vti tests fail when sending large UDP datagrams over > ip6_vti that require fragmentation and the underlying device has an > MTU smaller than 1500 plus some extra space for headers. This happens > because ip6_vti, by default, sets MTU to ETH_DATA_LEN and not updating > it depending on a destination address or link parameter. Further > attempts to send UDP packets may succeed because pmtu gets updated on > ICMPV6_PKT_TOOBIG in vti6_err(). > > In case the lower device has larger MTU size, e.g. 9000, ip6_vti works > but not using the possible maximum size, output packets have 1500 limit. > > The above cases require manual MTU setup after ip6_vti creation. However > ip_vti already updates MTU based on lower device with ip_tunnel_bind_dev(). > > Here is the example when the lower device MTU is set to 9000: ... > Reported-by: Petr Vorel > Signed-off-by: Alexey Kodanev Applied, thanks Alexey.