OSPF uses a hierarchical routing model that divides the network into areas. Within each area, every router has a database that contains information about the entire area network topology. The routers within an area use this information to calculate the shortest path to each destination.
If a primary route goes down, OSPF uses its backup routes to reroute traffic. OSPF has multiple ways to handle redundant or backup routes:
1. Equal-cost multipath routing (ECMP): OSPF can distribute traffic across multiple equal-cost paths. This allows for better utilization of network resources and redundancy in case one of the paths fails.
1. Route summarization: OSPF summarizes routing information to simplify the routing tables and reduce the number of entries. This helps to minimize the routing overhead and increase network efficiency.
1. Virtual links: If a route is lost and there are no backup routes present, OSPF can create a virtual link to connect two separate areas to restore communication.
Overall, OSPF is designed to handle redundant or backup routes in a very efficient and reliable way, ensuring that network traffic can always find a path to its destination.
