This paper addresses the scalability problem arising from rapidly increasing routing overhead at network expansion. Focusing on the OSPF (Open Shortest Path First) protocol, proposed is a hierarchical routing scheme of clustering a routing domain into areas. Supplemented to the scheme is a step to reinforce system performances, particularly reliability, against possible degradation resulting from OSPF hierarchy. Due to the unavailability of similar studies, simple experiments with small nerworks will be reported on, in place of comparative testing for the proposed scheme.