28.1.3 Stub area

You can configure an area as a stub area if it is not a backbone area and does not contain an AS boundary router. To do so, use the area stub configuration command.

The area border router does not employ external AS routes in stub areas. This reduces the amount of routing traffic in stub areas and minimizes the demand that route updates and route selection place on router resources. The area border router employs a default route in place of the external routes in the stub area.

If you execute the area stub command with the no-summary parameter specified, the area border router does not advertise routes from other areas (inter-area routes) into the stub. Routers in the stub area must use the default route to send any traffic outside the area.