OSPF Areas

Why more than one Area is used in an OSPF network?

OSPF supports load balancing, service type-based routing, and multiple routing forms, such as specific host routing and subnet routing.

NGAF devices enable and set OSPF dynamic routing protocol, including network configuration, interface configuration, parameter configuration, information display, debugging options, etc.

*to decrease the LSA flood (Routing Table Exchange)
*You may split your network into different zones (for instance, each campus would be a part of a distinct zone, and the main campus would be the backbone zone 0 area).
*You can set the failover up.
*If an issue arises in one place, it won't spread to other places

An Interior Gateway Protocol (IGP) called OSPF (Open Shortest Path First) is used to determine routing within a single Autonomous System (AS).
It is a form of autonomous system operation that carries out the Interior Gateway Protocol (IGP)-related link status routing protocol.

Multiple areas facilitate a hierarchical network design, which can be easier to manage and troubleshoot. It also allows for better route summarization and control over traffic flows.
Reduced SPF Tree Calculation

Smaller LSDBs and reduced LSA propagation result in faster OSPF convergence times. This means that the network can adapt more quickly to changes in the network topology.
Improved Scalability:

To be able to scale because the more layer 3 attached the more route is add to the table.

There are several reasons why more than one area is used in an OSPF network:

To improve performance. In some cases, dividing the network into areas can improve performance by reducing the amount of routing traffic that is generated. This is because OSPF routers only need to exchange routing information with routers in their own area.

To improve security. By dividing the network into areas, it is possible to restrict the flow of routing information between areas. This can help to improve security by preventing unauthorized access to routing information.

To isolate critical networks. For example, a company might choose to use a separate OSPF area for its critical production networks. This would help to protect the production networks from routing problems that might occur in other parts of the network.

To reduce the size of the link-state database (LSDB). Each OSPF router maintains a copy of the LSDB for its area. By dividing the network into areas, each router only needs to maintain a copy of the LSDB for its own area. This can significantly reduce the memory and CPU requirements on each router, especially in large networks.

To separate different departments or business units. For example, a large company with multiple departments might choose to use a separate OSPF area for each department. This would allow each department to have its own routing policy and would also help to improve security.

Multiple areas are used in an OSPF (Open Shortest Path First) network to improve scalability, reduce routing overhead, and enhance network performance. Using multiple areas in an OSPF network provides benefits such as reduced LSA flooding, faster convergence, enhanced scalability, easy summarization, and improved security and fault isolation.

Question 4:OSPF Areas?

Answer:

BackBone Area:

The backbone area is area 0. It plays the role of the central node in the OSPF network and the link information of other areas is transmitted through area 0. so generally OSPF area consists of all networks in area ID 0.0.0.0 which are attached to the routing devices.
Standard Area:

In this type of area, OSPF packets can be normally transmitted and they can support up to 1,2,3,4, and 5 LSAs(Link State Advertisements). Ensure optimal routing since all routers know about all routes
Stub Area:

As the name defines this type of area does not accept external routes and does not accept the link information of the other routers outside the area. these areas do not receive type 4 or 5 LSAs from their ABRs(Area Border Router).
Totally stubby area:

These are completely stub areas same as sub-area this type of area does not accept external routes and does not accept the link information of the other routers outside the area. It should be noted here that since the default route is sent using Type 3 LSAs, the complete stub area does not allow ordinary Type 3 LSA packets, but it supports this type of LSA with default routes. This area supports Type 1, Type 2 LSAs, and Type 3 LSAs with default routes.
Not so Stubby area:  

It also has to send external routes to other areas. This area supports 1, 2, 3, and 7 LSAs. An NSSA makes use of type 7 LSAs.The functionality of NSSA is to designate a normal (stub) NSSA, all routers in the area must be so configured: This allows an ASBR to advertise external links to an ABR, which converts the type 7 LSAs into type 5 before flooding them to the rest of the OSPF domain.

OSPF, or Open Shortest Path First, is a routing protocol that is used to distribute routing information within a single autonomous system (AS) in a network. One of the key features of OSPF is its ability to divide the network into multiple areas. This allows for more efficient and scalable routing, as well as improved network security and stability. Each OSPF area is a separate routing domain, with its own unique routing table. This allows for more efficient use of network resources, as well as reducing the size of the overall routing table.

Additionally, OSPF areas can be used to separate different parts of the network, such as different departments or locations, providing a degree of isolation and security. It's also possible to connect different areas together using a backbone area, which allows for communication between the different areas. This allows for a more efficient routing of traffic throughout the entire network, while still maintaining the benefits of separating the network into multiple areas. Overall, OSPF's use of multiple areas provides a powerful and flexible way to organize and manage large and complex networks.