Abstract: A hierarchical shortest path first (HSPF) protocol, routers of a network are grouped in areas, and routing and client subscription information are distributed through all levels of the network hierarchy in the same way. Each level of the hierarchy identifies its connections with its peers that have the same level of hierarchy, and represents areas outside its own as individual nodes. The number of levels of hierarchy is not limited to any particular number, and each level performs the same operations to share routing information and generate routes for data. Distribution of link-state and client subscription information begins at the router level, and continues up the levels of the hierarchy until distributed through the network.