Existing Quality of Service models are well defined in the data path, but lack an end-to-end control path mechanism that guarantees the required resources to bandwidth intensive services, such as video streaming. Current reservation protocols provide scalable resource reservation inside routing domains. However, it is primarily between such domains that scalability becomes a major issue, since inter-domain links experience large volumes of reservation requests. As a possible solution, we present and evaluate the Shared-segment based Inter-domain Control Aggregation Protocol, (SICAP) which affords the benefits of shared-segment aggregation, while avoiding its major drawback, namely, its sensitivity to the intensity of requests [l]. We present results of simulations that compare the performance of SICAP against that of the Border Gateway Reservation Protocol, (BGRP) which relies on sink-tree aggregation to achieve scalability.