Configure Route Summarization

Area border routers send summary link advertisements to describe the routes to other areas. To minimize the number of these advertisements that are flooded, you can configure the router to coalesce, or summarize, a range of IP addresses and send reachability information about these addresses in a single link-state advertisement.

To summarize a range of IP addresses, include the area-range statement at the [edit protocols (ospf | ospf3) area area-id] hierarchy level. To summarize multiple ranges, include multiple area-range statements.

[edit protocols (ospf | ospf3) area area-id]

area-range network/mask-length <restrict >; 

All routes that match the specified area range are filtered at the area boundary, and the summary is advertised in their place. If you specify the restrict option, the routes are filtered but no summary is advertised.