Open Shortest Path First (OSPFv2 and OSPFv3) | 711Configure stub areasOSPF supports different types of LSAs to help reduce the amount of router processing within the areas.Type 5 LSAs are not flooded into stub areas; the Area Border Router (ABR) advertises a default route intothe stub area to which it is attached. Stub area routers use the default route to reach external destinationsTo ensure connectivity in your OSPFv2 network, never configure the backbone area as a stub area.Use these commands in the following sequence, starting in EXEC Privilege mode to configure a stub area.Use the show ip ospf database process-id database-summary command syntax (Figure 413) in theEXEC Privilege mode To view which LSAs are transmitted.Figure 32-12. Command Example: show ip ospf process-id database database-summaryTo view information on areas, use the show ip ospf process-id command in the EXEC Privilege mode.Step Command Syntax Command Mode Usage1 show ip ospf process-id [vrfvrf name] databasedatabase-summaryEXEC Privilege Review all areas after they were configured todetermine which areas are NOT receiving type 5LSAs.vrf name: Show only the OSPF information tied to theVRF process.2 configure EXEC Privilege Enter the CONFIGURATION mode.3 router ospf process-id [vrf {vrfname}]CONFIGURATION Enter the ROUTER OSPF mode.Process ID is the ID assigned when configuringOSPFv2 globally (page 58).vrf name: Enter the VRF key word and instance name totie the OSPF instance to the VRF. All network commandsunder this OSPF instance are subsequently tied to theVRF instance.4 area area-id stub[no-summary]CONFIG-ROUTER-OSPF-idConfigure the area as a stub area. Use theno-summary keywords to prevent transmission into the area of summary ASBR LSAs.Area ID is the number or IP address assigned whencreating the Area (page 60).FTOS#show ip ospf 34 database database-summaryOSPF Router with ID (10.1.2.100) (Process ID 34)Area ID Router Network S-Net S-ASBR Type-7 Subtotal2.2.2.2 1 0 0 0 0 13.3.3.3 1 0 0 0 0 1FTOS#
