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

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

Marshall Eubanks wrote:
> Yes, I think so, this requires interdomain flooding, just like 
> interdomain MSDP in IPv4.
Actually, I don't think it does.  See comments below.

> However, you might be able to make ASM "SSM like" in that, if you
> find the group address by some means out of band, you can join to the RP 
> and either send or receive.
This is actually what is expected to happen.  The steps look like:

     1. A receiver finds out a group address from some means
        (e.g. SDR or a web page)
     2. The receiver issues an MLD Report Joining the group
     3. The receiver's DR will initiate the PIM Join process
     4. The Join message flows up to the receivers RP
     5. The RP recognizes the embedded RP format and extracts
        the owning RP address
     6. The receiver's RP issues an SPT join to the owning RP
        and creates forwarding state

One possible optimization is that the receiver's DR could issue
the SPT to the owning RP.

The sender side has two cases.

     1. A sender in the owning domain.  Nothing should be different
        here.

     2. A sender in a foreign domain.  This is the case that I
        have to do some work on.  In order for a receiver in
        another domain to know about this sender, information will
        have to flow to the owning RP.

> It is also not clear to me how this would work in, say, a 
> teleconference. Doesn't it limit the group to only _one_ RP? What 
> functionality does it give that either SSM or MSDP doesn't ?
One big advantage is the removal of inter-domain MSDP state.  And
the use of one RP is a downside of this approach.

Brian