You can configure the ASBR route aggregation to convert the routes with the same prefix to one route on the ASBR and send the route to other ASs.
You can choose whether to advertise the aggregated route, and set the cost of the aggregated route. When a lot of routes are imported, users can set the delay for advertising aggregated routes. In this way, the aggregated route information advertised each time contains more valid routes and the incorrect routing information caused by network flapping is avoided.
The command can be configured in the Autonomous System Border Router (ASBR). The command is used to aggregate the imported external routers in the aggregation address range. If the area is NSSA area, this command can also be configured on the ABR. ABR aggregates the LSA that is switched from Type-7 to Type-5.
ospf [ process-id ]
asbr-summary ip-address mask [ [ not-advertise | generate-null0-route ] | tag tag | cost cost | distribute-delay interval ] *
This command is valid for ASBRs only.
not-advertise: Indicates that the aggregated route is not advertised. If the parameter is not specified, the aggregated route is advertised.
distribute-delay: Specifies the delay for advertising the summarized route.