Hi, I have a backbone made by SDH technology and there are a lot of point of metro aggregation access places connected to. Connected to that access (up to 40 KM) place there are sinlge centers that r teach the final customer. All the structure is made by fiber optic. The idea is to use layer 3 equipment to connect the access places. Wthat about the topology; shoul be better use a ring to connet the access places? What about the spanning three protocol; how can I eliminate it?