> From: Francis Dupont <[EMAIL PROTECTED]>
> - there is no reason for using MLD for link local multicast groups > as far IPv6 (layer-3) is concerned. > > => there is a very well known reason: snooping by layer-2 switches. ...and which totally bogus, as such switch cannot utilize the information in any significant way. Remember, I'm talking about LINK LOCAL MULTICAST groups used in IPv6 NEIGHTBOR DISCOVERY. And, as linklocal all-nodes is ALREADY excempted from the MLD, what is left is *ONLY* the solicited node multicast. I vote that, it too is exempted. When is this joined? ONLY when node configures a NEW id for address, so what we are seeing on link, is two back-to-back messages: 1) join solicited node group (MLD), followed by 2) ND DAD probe I just can't see any significant use for the (1), even for layer-2 snooper. The probe alone carries exactly the same information as the useless MLD join. And whats worse, the switch will increase the probability of DAD "failing to do its suff"... (if it decides not to forward the DAD to all links based on some stale soft state -- it definetly cannot start querying at this point). Additionally, when ND is protected by IPSEC, the switch needs to do the IPSEC also. > - at least it should be optional for link local multicast groups used > in Neighbor discovery > > => I can't see how it can be optional: either it is useful so is > recommended/required, or it is not useful so is not > recommended/required. Right, I'm requesting it to be at least optional. I don't think it (MLD for link local ND groups) is useful for anything. > - illogical definition: you cannot join solicited nodes multicast > group before you have address, > > => I don't understand: I can send a join message. Yes, with "::" source address. Kinky.. :) > - if layer-2 snoop is going to make use of MLD, it or some part of it > must actually be node on the network > > => no, the layer-2 snooper is a layer-2 snooper by definition. Then it cannot send queries, and it's knowledge about solicited node groups is totally "soft", practically useless (unless it snoops other ND traffic, in which case it doesn't need MLD at all for those). > => s/would add/adds/ because MLD is mandatory. But you still can remove > the support of multicast on the links (and remove MLD too). Perhaps > this is the best solution if your argument is that multicast just sucks. Where did I say "multicast sucks". I definitely like multicast, I'm just talking about these link local groups here, and specifically about ND discovery part of it. -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
