We have designed a Clearing House (CH) architecture that facilitates resource reservations over multiple network domains, and performs local admission control. Two key ideas employed in this design to make the CH scalable to a large user base are hierarchy and aggregation. In our model, we assume the network is composed of various basic routing domains which can be aggregated to form logical domains. This introduces a hierarchical tree of logical domains and a distributed CH architecture is associated with each logical domain to maintain the intra-domain aggregate reservations. The parent CH in the logical tree maintains the inter-domain reservation requests. Call setup time is reduced by performing advanced reservations based on statistical estimates of the call traffic across various links. We explore, with simulations, the efficiency of the CH-architecture in terms of resource utilization, call rejections and reservation setup time.