Inter-area routing applies to inter-area topics. OSPF stipulates that routing information is not allowed to be published directly between two non-backbone areas. Routing information is only allowed…

Inter-area routing applies to inter-area topics. OSPF stipulates that routing information is not allowed to be published directly between two non-backbone areas. Routing information is only allowed to be published within an area, or between a backbone area and a non-backbone area. Therefore, each Area Border Router (ABR) must be connected to the backbone area.