From nobody Wed Feb 23 15:51:38 2022 X-Original-To: freebsd-net@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id DB0F719CFA05 for ; Wed, 23 Feb 2022 15:52:01 +0000 (UTC) (envelope-from lutz@iks-jena.de) Received: from annwfn.iks-jena.de (annwfn.iks-jena.de [IPv6:2001:4bd8::19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 4K3gX03vgyz4dNP for ; Wed, 23 Feb 2022 15:52:00 +0000 (UTC) (envelope-from lutz@iks-jena.de) X-SMTP-Sender: IPv6:2001:4bd8:0:666:248:54ff:fe12:ee3f Received: from belenus.iks-jena.de (belenus.iks-jena.de [IPv6:2001:4bd8:0:666:248:54ff:fe12:ee3f]) by annwfn.iks-jena.de (8.15.2/8.15.2) with ESMTPS id 21NFphf8030362 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Wed, 23 Feb 2022 16:51:44 +0100 X-MSA-Host: belenus.iks-jena.de Received: (from lutz@localhost) by belenus.iks-jena.de (8.14.3/8.14.1/Submit) id 21NFpcXo023045; Wed, 23 Feb 2022 16:51:38 +0100 Date: Wed, 23 Feb 2022 16:51:38 +0100 From: Lutz Donnerhacke To: "Scheffenegger, Richard" Cc: "freebsd-net@freebsd.org" Subject: Re: IPv6 - NS, DAD and MLDv2 interaction Message-ID: <20220223155138.GA22544@belenus.iks-jena.de> References: List-Id: Networking and TCP/IP with FreeBSD List-Archive: https://lists.freebsd.org/archives/freebsd-net List-Help: List-Post: List-Subscribe: List-Unsubscribe: Sender: owner-freebsd-net@freebsd.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-message-flag: Please send plain text messages only. Thank you. User-Agent: Mutt/1.5.17 (2007-11-01) X-Rspamd-Queue-Id: 4K3gX03vgyz4dNP X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; dkim=none; dmarc=none; spf=pass (mx1.freebsd.org: domain of lutz@iks-jena.de designates 2001:4bd8::19 as permitted sender) smtp.mailfrom=lutz@iks-jena.de X-Spamd-Result: default: False [-3.09 / 15.00]; TO_DN_EQ_ADDR_SOME(0.00)[]; ARC_NA(0.00)[]; RCVD_TLS_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; R_SPF_ALLOW(-0.20)[+ip6:2001:4bd8::/48]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[donnerhacke.de]; NEURAL_HAM_MEDIUM(-0.99)[-0.994]; TO_MATCH_ENVRCPT_SOME(0.00)[]; NEURAL_HAM_SHORT(-1.00)[-1.000]; RCPT_COUNT_TWO(0.00)[2]; MLMMJ_DEST(0.00)[freebsd-net]; FORGED_SENDER(0.30)[lutz@donnerhacke.de,lutz@iks-jena.de]; RCVD_IN_DNSWL_LOW(-0.10)[2001:4bd8:0:666:248:54ff:fe12:ee3f:received]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_TWO(0.00)[2]; ASN(0.00)[asn:15725, ipnet:2001:4bd8::/29, country:DE]; FROM_NEQ_ENVFROM(0.00)[lutz@donnerhacke.de,lutz@iks-jena.de] X-ThisMailContainsUnwantedMimeParts: N On Wed, Feb 23, 2022 at 01:46:32PM +0000, Scheffenegger, Richard wrote: > As far as I know, an IPv6 host initially tries to perform Duplicate > Address Detection, as well as Neighbor Discovery / Neighbor Solicitation. > All of this typically works on Ethernet, by mapping into a well-known > Ethernet multicast destination MAC “33-33-xx-xx-xx-xx”. Yup. IPv6 replaced broadcast by multicast on the link layer. > It appears that some vendors of switches have started to become overly > restrictive in forwarding Ethernet Multicast, and only deliver these *after* > a Host has registered itself to receive / participate in specific IPv6 > Multicast groups. May you please drop an information about the vendor? So that we can warn the community to buy those broken products. > So far, I could not find any guidance (and with my lack of depth into > IPv6, it is also unclear to me, if this would even be possible) if > registering a host into a IPv6 MC group via MLDv2 in order for it to receive > NS, ND, DAD is something that would be expected… https://datatracker.ietf.org/doc/html/rfc4861#section-7.2.1 The host must join (using MLDv2) the multicast groups for all of its own addresses to be reachable by Neighbor Discovery. This does not include the standard RD group (IIRC).