Configuring a stub area
You can configure a non-backbone area at an AS edge as a stub area. To do so, execute the stub command on all routers attached to the area. The routing table size is reduced because Type-5 LSAs will not be flooded within the stub area. The ABR generates a default route into the stub area so all packets destined outside of the AS are sent through the default route.
To further reduce the routing table size and routing information exchanged in the stub area, configure a totally stub area by using the stub [ no-summary ] command on the ABR. AS external routes and inter-area routes will not be distributed into the area. All the packets destined outside of the AS or area will be sent to the ABR for forwarding.
A stub or totally stub area cannot have an ASBR because external routes cannot be distributed into the area.
To configure an OSPF stub area:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter OSPF view. | ospf [ process-id | router-id router-id | vpn-instance vpn-instance-name ] * | N/A |
3. Enter area view. | area area-id | N/A |
4. Configure the area as a stub area. | stub [ default-route-advertise-always | no-summary ] * | By default, no stub area is configured. |
5. (Optional.) Specify a cost for the default route advertised to the stub area. | default-cost cost | The default setting is 1. The default-cost cost command takes effect only on the ABR of a stub area or totally stub area. |