Configure Dynamic Routing OSPF.

What is OSPF?

OSPF Open Shortest Path Fast is a link state routing protocol developed based on Open Stranded. So it works with other routers, including Cisco. OSPF is used as the gateway protocol for the interior.

How does OSPF work?

OSPF sends LSA ads to all routers in one area. This LSA includes the value of the linked interface, the value of the metric, and the value of other variables and uses the SPF algorithm. This algorithm provides a path to startup and low cost. This SPF algorithm is known as the Dijkstra algorithm.

Features of OSPF:

⇰  OSPF divides the routing domain into an area.

⇰  Route updates only when the route is changed.

⇰  The only route that has changed is the information on the LSA (Link State Advertising).

⇰  Hello exchanges massages to build a neighbor.

⇰  Supports OSPF variable length subnet mask (VLSM) and classless inter domain routing (CIDR).

⇰  OSPF supports numerous network hops.

⇰  The multicast addresses of the OSPF are (224.0.0.5 and 224.0.0.6).

⇰  The algorithm used is Dijkstra's Shortest Path Fast.

OSPF Networking Hierarchy:

One of the interesting things of the OSPF is how it divides the network into several areas and hierarchies. As a result, it collects all the information from an area border router.

Area 1 is where the backbone routers are located. Area 3 is connected to the area border routers. Autonomous System border router is used to connect to any other routing domain.

Another interesting thing is the table:

OSPF uses 3 tables- neighbor table link-state table and routing table. The combination of these three tables gives the OSPF the entire network image.

Neighbors table:

This table contains information about which router is adjacent to a router.

Link state table:

This table contains information about the status of any of the links associated with neighboring routers.

Routing table:

The routing table will contain information about the cost of each link in the Link State table.