Draft-Rosen (GRE) mVPN - the need for bgp ipv4 mdt AF?
I'd like to clarify my understanding of GRE-based Draft-Rosen concepts. I've been watching relevant ATC (#40) where in the configuration example Brian configured PIM-SM in the SP core network. The last step to tie whole design together was to configure BGP IPv4 MDT Address Family.
This is something I'm confused about. I thought that BGP messages are only needed when running PIM SSM in the core network.
When using PIM ASM, the PE routers know the RP address, so they can register and join particular P multicast group.
In case of SSM it is not possible, so they have to rely on some external mechanism to discover each other.
Is my understanding correct?