Flat OSPF network, or single area OSPF networks are real. In fact most of the OSPF network today deployed, is flat OSPF networks. But how many routers can be placed safely in an OSPF area ? Any number from the real world OSPF deployment ? I will share in this post.
OSPF Area Types – Different Areas in OSPF are used to create smaller fault domains. There are two OSPF area types in total.
OSPF Backbone area and OSPF non-backbone area
Backbone area in OSPF is Area 0. OSPF prevents loop by using backbone area concept.All the non-backbone areas should be connected to the Backbone area.
There are many Non-Backbone OSPF Area types. These are; Normal Area, Stub, Totally Stub, NSSA and Totally NSSA Areas.
In this article I will explain the non-backbone OSPF areas from the design point of view and share some caveats about the OSPF design.
Flooding in full-mesh topology is a big concern for network-design experts, especially in large-scale OSPF deployments. When the link or node fails in an OSPF network, failure information is flooded everywhere in the same area. If Flat OSPF network design is used, then the problem gets bigger. Each router receives at least one copy of the new information from each neighbor.