Jonathan wrote:

> That depends.  *someone* needs to do a check on the multicast
> addresses, since the hash from link-level address to a 6-bit bit-index
> might collide.  IPmulticast has to do an IP-level check anyway, since
> for braindead historical reasons, there's a similar many-to-one
> mapping from IPmulticast to link-level Ethernet addreses.  So you for
> IP at least, don't need to do a check.

Thats not the only reason. RFC1122 explicitly states that for link
types which only have one multicast address (the broadcast address),
all IP multicast packets are mapped to that one. (One of them is
ARCnet, supported by NetBSD).

(And if I recall right, for IPv6 there aren't enough Ethernet multicast
addresses to map all possible IPv6 multicasts on, one to one).

Regards,
	Ignatios Souvatzis