[manet] RPF for meshes

[Juliusz Chroboczek <[e-mail]>]

Hi,

At today's joint MANET-Babel meeting, somebody (I don't recall who)
mentioned that we might be able to solve the multicast problem by looking
at the Ethernet header.  That got me thinking, and perhaps the following
modification to RTP that works with MAC addresses instead of insterfaces
could be made to work.

When you receive a multicast patcket S->G, you lookup S in your unicast
routing table; this gives you a next-hop address A.  You perform address
resolution on A, this yields a MAC address M.  If the layer 2 source
address of the packet is not M, you drop the packet.

The procedure above clearly avoids loops if your unicast routing graph is
loop-free, since it enforces that multicast packets follow the reverse
unicast path.

I'm sure it breaks something, but what?

-- Juliusz