v6-in-v4 configured tunneling over v4 multicast (vs 6over4)

[Pekka Savola <pekkas@netcore.fi>]

Hi,

When discussing draft-savola-v6ops-tunneling-01.txt with Dave Thaler, 
mainly about the necessity of 6over4 in the scenario where the IPv4 
network is multicast-enabled but the v6 network is not, I came up with 
an idea which I'm not sure if others have brought up in the past:

If you want to create point-to-multipoint tunnels over v4 multicast
infrastructure, wouldn't the obvious solution be simply using
configured tunneling?  That is, you configure the tunnel destination
v4 address to be a multicast address (this requires zero code
changes), and the decapsulators configure their "local end" to be the
multicast address (requires code change in the tunnel setup tool to
permanently join the specified multicast address)?

This would seem to act like a "statically mapped", simplified
alternative to 6over4 which would only require an
implementation-specific addition to join the multicast group.

This is in line with RFC2893 and draft-ietf-v6ops-mech-v2-02.txt, as 
long as you interpret section 3.6 loosely enough:

   When an IPv6/IPv4 host or a router receives an IPv4 datagram that is
   addressed to one of its own IPv4 addresses, [...]

(this wording could be tuned, obviously.)

Thoughts?

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings