Configuring a stub area
Configure a non-backbone area at the AS edge as a stub area by configuring the stub command on all the routers attached to the area. In this way, Type-5 LSAs will not be flooded within the stub area, reducing the routing table size. 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 it as a totally stub area by using the stub [ no-summary ] command on the ABR. In this way, neither AS external routes nor inter-area routing information will be distributed into the area. All the packets destined outside of the AS or area will be sent to the ABR for forwarding.
To configure OSPF areas:
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 ] * | Not configured by default. You must use the stub command on routers attached to a stub area. The backbone area cannot be a totally stub area. A (totally) stub area cannot have an ASBR because AS external routes cannot be distributed into the stub area. |
5. Specify a cost for the default route advertised to the stub area. | default-cost cost | Optional. 1 by default. The default-cost command takes effect only on the ABR of a stub area. |
![[NOTE: ]](images/note.png) | NOTE: Virtual links cannot transit totally stub areas. | |