> A more complicated issue is where to bind(2) to: In theory, the
> user is supposed to pass an sin6_scope_id pointing to the interface
> to use. In the link-local-multicast case, this leads to an
> inconsistency: IPV6_JOIN_GROUP has a notion of "pick yourself",
> but the bind(), which has to happen before, has not. This means
> that the "pick yourself" option of IPV6_JOIN_GROUP is quite useless,
> if one doesn't just use an in6addr_any socket.
> I haven't found any RFC considering this case.
> Any clues?

	there's no standard AFAIK.  i would suggest specifying interface
	explicitly, always, even with IPV6_JOIN_GROUP.

itojun