Re: New draft on embedding the RP address in IPv6 multicast address

[Brian Haberman <bkhabs@nc.rr.com>]

Mike O'Connor wrote:
> Hi Brian,
>
> I don't understand how the reciever's RP receives the "owning RP"
> address for a given multicast group. How are the "owning RP" addresses
> distributed between domains without PIM flooding?
The RP address is embedded in the multicast address.  The key is in the
assignment of multicast addresses in a domain and the configuration of
RP addresses.

So, if a domain uses prefix 3ffe:1:2::/48.  It places an RP in the
network and gives it an address of 3ffe:1:2:3::5.  Now, this RP can
be the RP for the multicast address range FF7x:0540:3ffe:1:2:3::/96.
The key is that the IID portion of the RP's address is set to a value
that can be encode in the RPad field of the multicast address.  The
mcast groups are distinguished by the lower 32 bits of the address.

Now, a receiver's RP can examine the multicast address when it is
creating state and reconstruct the owning RP's address by extracting
the network prefix value and appending the RPad field.

Brian