So in the following case: - source attached to V-hub2 - receiver attached to V-spoke1 - V-spoke1 associated with V-hub1
I was questioning whether it is really necessary to have a data path of source-->V-hub2-->V-hub1-->V-spoke1-->receiver, or whether we could have the more optimal data path of source-->V-hub2-->V-spoke1-->receiver If I understand correctly, the answer is that in order to obtain the more optimal path: 1. We would need a new procedure for determining which packets need to be discarded because they come from the "wrong place"; this would have to be tunnel-based rather than sender-based. (A similar issue arises in extranet.) 2. This procedure would require more BGP routes to be sent from a v-hub to its associated spokes, since in hub has to tell its associated spokes the tunnel to use for each (S,G). (This makes it difficult to use I-PMSI or (*,*) S-PMSI A-D routes in the hub-to-associated-spoke control plane.) While I agree that these points are valid, I don't see 1 as a real issue, and 2 is a common tradeoff (increasing the optimality of the data plane requires more control messages). The issue of unsolicited flooded data is really a sub-issue of 2. However, in the context of WG LC, I think you have adequately answered the question of why it makes the choice it does.
