This paper presents a study on a scalable inter-domain signaling protocol to provide quality of service to the Internet. The protocol uses a hard-state approach and separates data forwarding procedures, control procedures, and resource allocation procedures. Current solutions adopt a soft-state label switching approach where border routers are responsible for maintaining resource accounting and the path's next-hop information for every aggregated flow. Due to the Internet's almost hierarchical structure, the routers at the core can become a bottleneck to the system's overall scalability. Our protocol, SIDSP, reduces the core routers complexity by transferring most of the state data to the peripheral routers. This is accomplished by the usage of source routing for the flows. As a hard-state approach, it does not require periodical refreshing messages. However it puts more pressure on state coherence and state stabilization algorithms. SIDSP's performance was tested using ns-2 simulations, and was compared to BGRP's performance.