This paper addresses the scalability problem arising from rapidly increasing routing overhead at network expansion. Focusing on the OSPF (Open Shortest Path First) protocol, we propose a hierarchical routing scheme of partitioning a routing domain into areas. Supplemented to the scheme is a step to reinforce system performances, particularly reliability, against possible degradation from domain partitioning. For an Internet service provider with its own domain, the framework provides a practical vehicle for scalable hierarchical routing indispensable to overall service quality. Due to the unavailability of similar studies, a simple experiment with a small network is reported on, in place of extensive comparative testing.