OSPF network aggregation involves combining multiple subnets into a single prefix to simplify routing tables and reduce the number of OSPF routes. Here are the steps to configure OSPF network aggregation:
1. Identify the subnets to be aggregated: Choose the subnets that can be summarized into a larger prefix. These subnets should be contiguous and connected.
1. Configure OSPF on each router: Enable OSPF on each router in the network and ensure that each router has a unique router ID.
1. Configure area ID and type: Assign each router to a specific area and configure the area type as needed (e.g., area 0 for backbone area).
1. Configure OSPF network aggregation: Configure the network aggregator router to aggregate the chosen subnets into a single prefix using the “network” command.
1. Verify OSPF network aggregation: Check the routing table on each router to ensure that the aggregated prefix is visible and that the correct OSPF routes are being used.
1. Test connectivity: Check that all hosts on the network can communicate with each other using the new aggregated prefix.
Example configuration:
Router A:
router ospf 1
network 10.1.1.0 0.0.0.255 area 0
network 10.1.2.0 0.0.0.255 area 0
Router B:
router ospf 1
network 10.1.3.0 0.0.0.255 area 0
network 10.1.4.0 0.0.0.255 area 0
Router C (aggregator):
router ospf 1
network 10.1.0.0 0.0.255.255 area 0
In this example, Router C aggregates the subnets 10.1.1.0/24, 10.1.2.0/24, 10.1.3.0/24, and 10.1.4.0/24 into the prefix 10.1.0.0/16.
