From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Wragg Subject: Re: [PATCH net v2 2/3] geneve: Relax MTU constraints Date: Wed, 10 Feb 2016 11:41:55 +0000 Message-ID: <86a8n86bcs.fsf@weave.works> References: <1455036424-6403-1-git-send-email-david@weave.works> <1455036424-6403-3-git-send-email-david@weave.works> Mime-Version: 1.0 Content-Type: text/plain Cc: Linux Kernel Network Developers , dev@openvswitch.org, Jesse Gross , David Miller , Hannes Frederic Sowa , Thomas Graf , Roopa Prabhu To: Tom Herbert Return-path: Received: from mail-wm0-f54.google.com ([74.125.82.54]:35552 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753102AbcBJLl6 (ORCPT ); Wed, 10 Feb 2016 06:41:58 -0500 Received: by mail-wm0-f54.google.com with SMTP id c200so24352006wme.0 for ; Wed, 10 Feb 2016 03:41:57 -0800 (PST) In-Reply-To: (Tom Herbert's message of "Wed, 10 Feb 2016 08:40:55 +0100") Sender: netdev-owner@vger.kernel.org List-ID: Tom Herbert writes: > The correct thing to do is determine the maximum amount of > encapsulation overhead that can ever be set in a packet and use for > setting the MTU. For instance, when RCO is enable in GUE, the size of > the option is included in tunnel->encap_hlen even though it will not > be used in all packets (via ip_tunnel_change_mtu). If there is no way > to determine a maximum overhead a priori from configuration, then > maximum overhead could be assumed to be maximum possible encapsulation > header size which for Geneve is 132 bytes IIRC. Ok, I'll come up with a patch to address this. David