[GROW] draft-ietf-grow-va-00 and multicast

["John G. Scudder" <jgs at juniper.net>]

Draft-ietf-grow-va authors,

In looking over the draft, it's not clear how multicast would work.   
For example, in the case discussed in 3.2.3, how would the border VA  
router perform an RPF check on multicast traffic received from an  
adjacent AS if the VA router doesn't have a route to the source of the  
traffic (other than some flavor of default which is pointing down a  
tunnel in the wrong direction)?

Similarly, in the case where traffic from a border router goes to an  
APR and then back to the same border router, how does PIM work?  It  
would appear that in this case the incoming and outgoing interfaces  
used by PIM could be the same.  More generally, have you thought  
through how PIM works in the VA world, period?  Seems like questions  
to be looked at include how PIM messages flow (tunneled, native), how  
multicast data traffic flows, and so on.  Perhaps there are simple  
answers to these but they weren't evident to me.

Thanks,

--John