> From: Brian Haberman <[EMAIL PROTECTED]> > Markku Savela wrote: > >>From: Brian Haberman <[EMAIL PROTECTED]> > >>>- desire to avoid packet storms upon booting many nodes simultaneously > >> > >>2710 accomplishes this by using message suppression. If a node hears a > >>Report for the same group, it cancels the transmission of any pending > >>Reports it has for the group. > > > > > > Above will totally fail with ND multicast groups. Their design goal is > > that each host is only on one group. It is highly unlikely that > > listening would hear a duplicate join for the solicited node multicast > > address. > > It is not a failure, it is just not useful for solicited-node multicast > addresses. But, you also snipped a part of the note that pointed out > that ND and MLD were designed with differing techniques to deal with > reliability.
Perhaps MLD has evolved since I last looked at the WG group. However, I believe using MLD snooping switches makes your network unreliable. Let me iterate my reasoning (maybe MLDv2 has been fixed since, but..). All of the following relates only to solicited node multicast groups: - if MLD join on DAD is lost, it does not only break DAD, it also makes that node invisible to all other nodes behind the snooping swith (because no ND traffic related to that group is passed through). - to recover, someone is supposed to request MLD report from all nodes on the link. - who sends this request? As far as I understand, only multicast routers are requesting those reports? Is running a multicast router now obligatory MUST on every link? - ok, you can say the snooping switch sends the report request occasionally. But, then the switch must have IPv6 link local address, it must implement at least part of the IPv6 ND. It might as well note the ND DAD messages. - when report request is sent, EVERY node on the link going to reply, and without a delay. Isn't this going to raise the probability that some of the replies are lost? If so, then again we have some nodes, whose ND is not working over the switch. How do recover from this cycle? - if your switch boots, it has to request reports from all links, and it can enable the filtering only after it is sure that it has a complete picture of joined groups. Again, a storm of replies, possibility of lost answers? Are such switches used to bridge WLAN's? Are existing MLD snooping switches currently really trying to work on link local groups (and especieally solicited node)? Or, are they just passing all and ingoring link local groups? Have they really though over the issues above? Is this a "snake oil" product, as far as solicited node groups are considered? :-) -------------------------------------------------------------------- IETF IPv6 working group mailing list [EMAIL PROTECTED] Administrative Requests: https://www1.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
