From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.zx2c4.com (lists.zx2c4.com [165.227.139.114]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D055EC6FA8F for ; Wed, 23 Aug 2023 17:18:27 +0000 (UTC) Received: by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTP id a0515b07; Wed, 23 Aug 2023 17:14:55 +0000 (UTC) Received: from janet.servers.dxld.at (mail.servers.dxld.at [5.9.225.164]) by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTPS id b7048b88 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO) for ; Wed, 23 Aug 2023 17:14:53 +0000 (UTC) Received: janet.servers.dxld.at; Wed, 23 Aug 2023 19:14:52 +0200 Date: Wed, 23 Aug 2023 19:14:51 +0200 From: Daniel =?utf-8?Q?Gr=C3=B6ber?= To: Marek =?utf-8?B?S8O8dGhl?= Cc: wireguard@lists.zx2c4.com, luizluca@gmail.com Subject: Re: IPv6 and PPPoE with MSSFIX Message-ID: <20230823171451.ld2fwslkl6blv6y2@House.clients.dxld.at> References: <20230823165840.7bf3b910@parrot> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20230823165840.7bf3b910@parrot> X-BeenThere: wireguard@lists.zx2c4.com X-Mailman-Version: 2.1.30rc1 Precedence: list List-Id: Development discussion of WireGuard List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: wireguard-bounces@lists.zx2c4.com Sender: "WireGuard" Hi, On Wed, Aug 23, 2023 at 04:58:40PM +0200, Marek Küthe wrote: > PPPoE adds 8 bytes of overhead so that an MTU of 1432 can be used. I > also have to do this at home with my DSL line for example. > The MTU should be set on each side (on both peers) for this to work. Oh, I just realized I used the 1432 MTU in my earlier reply based on Marek's math but since Luiz's underlay network is IPv6 this is not actually correct. MTU=1440 is only correct on top of IPv4, for IPv6 the "optimal" MTU is 1420 so with PPPoE involved that's MTU=1412. 1500 Ethernet payload -40 IPv6 header -8 UDP header -32 Wg header -8 PPPoE =================== 1412 wg tunnel MTU --Daniel