Date: Wed, 23 Feb 2022 16:51:38 +0100 From: Lutz Donnerhacke <lutz@donnerhacke.de> To: "Scheffenegger, Richard" <Richard.Scheffenegger@netapp.com> Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org> Subject: Re: IPv6 - NS, DAD and MLDv2 interaction Message-ID: <20220223155138.GA22544@belenus.iks-jena.de> In-Reply-To: <PH0PR06MB763932835F5EE4228A1402C6863C9@PH0PR06MB7639.namprd06.prod.outlook.com> References: <PH0PR06MB763932835F5EE4228A1402C6863C9@PH0PR06MB7639.namprd06.prod.outlook.com>
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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).
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