The issue Andrew and Tony were raising was a bit more simple and a bit more complicated on several fronts. Let's start with a picture: MAE-WEST PBNAP MAE-EAST 39.0/10 39.64/10 39.128/10 A------| S----| A--| S------| M----| S--| M------| N9---| M--| N9-----| NE---| N9-| NE-----| Y----| NE-| X------| Z--| In normal conditions: How does X get traffic to Y? How does Y get traffic to X? How does X get traffic to Z? How does Z get traffic to X? How does Y get traffic to Z? How does Z get traffic to Y? How does A get traffic to Y? How does Y get traffic to A? Where can 39.0/9 be aggregated? Where can 39/8 be aggregated? What are the side-effects of both these aggregations when things are operating normally? In failure conditions: If S falls off MAE-WEST, how does it get traffic to the customers of A, M, N9, NE and X that are addressed by 39.0/10? How do A, M, N9, NE, and X get to S's customers that are addressed by 39.0/10? If A falls off MAE-WEST, how does it get traffic to the customers of A, M, N9, NE, and X that are in 39.0/10? How does it get to all of 39.0/9? How does the rest of the world get to A's customers that are addressed in 39.0/10? What happens in both these cases to traffic between Z and everything in 39.0/9, in each direction? These definitely are not hypothetical questions. If geographical or stratum-based allocation that is not _also_ provider-based is to fly, this is precisely the type of thing that must be dealt with. Sean.