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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C8CBCC47082 for ; Mon, 7 Jun 2021 12:00:16 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id DE78B611AD for ; Mon, 7 Jun 2021 12:00:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DE78B611AD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=employees.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=wireguard-bounces@lists.zx2c4.com Received: by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTP id b6dba530; Mon, 7 Jun 2021 11:58:33 +0000 (UTC) Received: from clarinet.employees.org (clarinet.employees.org [198.137.202.74]) by lists.zx2c4.com (ZX2C4 Mail Server) with ESMTPS id c89cd5ea (TLSv1.3:AEAD-AES256-GCM-SHA384:256:NO) for ; Mon, 7 Jun 2021 11:58:31 +0000 (UTC) Received: by clarinet.employees.org (Postfix, from userid 1736) id EB4614E11CA8; Mon, 7 Jun 2021 11:58:29 +0000 (UTC) Date: Mon, 7 Jun 2021 12:58:29 +0100 From: Derek Fawcus To: Peter Linder Cc: wireguard@lists.zx2c4.com Subject: Re: potentially disallowing IP fragmentation on wg packets, and handling routing loops better Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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" On Sun, Jun 06, 2021 at 01:14:16PM +0200, Peter Linder wrote: > This would break things for me. We're doing a lot of L2 over L3 site to > site stuff and we are using wireguard as the outer layer. Inner layer is > vxlan or l2tpv3. > > In particular, people connect lots of stuff with no regard for MTU. For > some things it's also very hard to change so we just assume people > don't. Since the L3 network typically has the same MTU as the inner L2 > network, we need fragmentation. There is no practical way to be able to > tell hosts on the L2 network about the limited mtu, for all we know they > don't even run IP.... I've not looked in to vxlan much, but for L2TP you always have recourse to RFC 4623, where the MRU & MRRU can be exchanged. DF