Abstract Open Shortest Path First (OSPF) currently supports multiarea networking with two severe limitations: the multiarea topology is restricted to a two‐level hierarchy, and globally optimal routing may not be achieved. An OSPF extension that overcomes these limitations is proposed by introducing a routing overlay for the dissemination of multiarea routing information. It applies to both OSPFv2 (IPv4) and OSPFv3 (IPv6) and is transparent to area‐internal routers. The extension was fully implemented and tested, and the results show that the added functionality is completely achieved, at the cost of a small penalty in terms of convergence times for small networks.