the upper SP's placement function (*) decides that (let's assume the NS involves VNF-1 & VNF-2) it is not best placed to implement VNF-2 (either it can't do it, or it knows it's better to do it in the remote PoP)
the lower SP's placement function decides where to place VNF-2
(*) placement function or SSM - where the different functionality lies is a bit fuzzy to me
In the Pilot, we can do whatever's easiest. For instance, the placement functions could have a built-in decision (default option), so effectively not have to decide each time.
How does the Lower SP places the VNFs? Does the placement SSM get deployed in Sp-Red as well?