[openib-general] IPv6 All Router Multicast Group

[Roland Dreier]

    Hal> So an end node doesn't find available routers via this group
    Hal> ?  What you are saying is consistent with the observations
    Hal> for this and the router would create the group and there is
    Hal> no one to send to if the group isn't there (send only join).

Yes, see RFC 2461 -- router advertisements are sent to the all-nodes
group (although to be precise, solicited advertisements MAY be unicast
to the requestor).

    Hal> A host needs to tell the multicast router when it is joining
    Hal> and leaving a group so the router knows when to join the
    Hal> multicast tree for that group or prune the tree.
 
If the host does not need to receive any multicast messages, then only
the multicast routers would need to join the group.

 - R.