OSPF ABR will not generate default LSA to stub area when area 0 has only one router

How to inject a default route to address the OSPF area border router (ABR) not generating a default link-state advertisement (LSA) to stub area when area 0 has only one router.

When area 0 has only one router, OSPF ABR will not generate default LSA to stub area. We need to inject default route to stub area.

Topology:

Junos OS supports active backbone detection. Active backbone detection is implemented to verify that ABRs are connected to the backbone. If the connection to the backbone area is lost, then the routing device’s default metric is not advertised, effectively rerouting traffic through another ABR with a valid connection to the backbone.

Junos OS does not generate the default LSA if ABR does not have any active backbone connection (any adjacency in area 0). If only one router exist in area 0, there is a hidden command which will change this behavior. You can configure following command on ABR.

 

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Prasanna

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