OSPF (Open Shortest Path First) is a routing protocol used to distribute routing information across a network to enable routers to dynamically find the best paths to reach a particular destination.
OSPF uses a Link State Routing (LSR) algorithm to build a topology database of the entire network by exchanging OSPF packets called Link State Advertisements (LSAs) between routers. Each router in the network maintains a database of LSAs, which contains information about the state of its directly connected links, including their IP address, subnet mask, and network type.
Based on this information, each router creates a map of the network topology, which it uses to calculate the shortest path to a destination. OSPF uses the Dijkstra algorithm to calculate the shortest path, taking into account the cost of each link based on their bandwidth and delay.
Once the shortest path is calculated, the router updates its routing table and sends updates to its neighboring routers, which in turn update their routing tables. This process continues until all routers have updated their routing tables and the network reaches a stable state.
If a link goes down or a new link is added to the network, OSPF will automatically re-calculate the shortest path and update its routing tables accordingly. This ensures that the network remains highly available and resilient to changes.
Overall, OSPF is a robust and efficient routing protocol that enables routers to dynamically learn and adapt to changes in the network topology, while balancing network traffic across multiple paths to improve performance and minimize congestion.
