Advantages of Centralized Routing
Information such as SRLG’s and performance parameters which change infrequently and are unlikely to be amenable to self-discovery could reside in a central database and would not need to be advertised.
Routing dependencies among circuits (to ensure diversity) is more easily handled centrally when the circuits do not share terminals since the necessary state information should be more easily accessible in a centralized model.
Pre-computation of restoration paths and other computations that can benefit from the use of global state information may also benefit from centralization.