[openib-general] IPv6 All Router Multicast Group

[Hal Rosenstock]

Roland Dreier wrote:
>     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.

In IGMP, the host needs to both listen (for queries) and send (reports,
leave).
The inverse is true for mrouters. It seems like they both need to join the
group
if they are running IGMP of some version. IGMPv1 does not support leave.

-- Hal