While this might be possible this scheme would cause some administrative problems. Currently the backbone ENSS's and CNSS's carry full external routes in their tables, with each ENSS having an IBGP session with all other nodes. I think a better long term solution would be to try to move away from using default and on to full routing information exchange at AS borders (using aggregation of course). An example of the kind of problem we would run into using the ENSS-filtering approach is that all peers of that ENSS would have to use the same policy. Why not split the ENSS's out of the IBGP "cloud" and use external-BGP between the ENSS's and CNSS's? This would likely require that an addition AS number and non-140.222 network be assigned to each ENSS, but it seems to fit more logically into the CNSS/ENSS architecture. It would also greatly reduce the number of IBGP sessions inside the T3 backbone. Comments? --Vince