The OSPF Area Stub does not accept external routes and does not accept the link information of other areas outside of their own area. Several region types are used by OSPF (Open Shortest Path First) OSPF Area Stub to optimize routing in big networks. The five OSPF area types are as follows:
1. Backbone Area (Area 0) Overview:
The OSPF network’s backbone area, sometimes referred to as Area 0, is its hub. It acts as the hub for the interchange of routing data, connecting all other locations.
Supported LSA Types: 1, 2, 3, 4, and 5
2. Standard Area
Description: Routing packets for OSPF types of areas are transmitted regularly in this OSPF area type, which is the default. The complete set of OSPF Link-State Advertisements (LSAs) is supported.
Supported LSA Types: 1, 2, 3, 4, and 5
3. Stub Area
Description: An area designated as a stub cannot take external routes from outside of OSPF. Rather, it employs a default path to get to other locations. As a result, less routing information is shared.
Supported LSA Types: 1, 2, and 3
4. Completely Stubby Space
This kind of region is considerably more constrained than a stub area. It uses only a default route to access networks outside of the area and does not accept external routes or inter-area link information.
Supported LSA Types: 1 through 3 (for default routes).
5. The Not-So-Stubby Area
The NSSA is an expansion of the stub area that minimizes the interchange of routing information while enabling the import of external routes.
Supported LSA Types: 1, 2, 3, and 7. You can have an NSSA in a Totally Stubby Area environment using the NSSA setup, which permits While providing default routes for Class 1, Type 2, and Class 3 LSAs, Type 7 LSAs will introduce external routes.
By regulating the distribution and breadth of routing information, an understanding of these area types facilitates the design of effective OSPF networks.