OSPF cannot import IBGP routes. Routes learned via IBGP must not be imported into OSPF. OSPF, however, can import IBGP routes on a PE.

BGP routes exist in a VPNv4 routing table on a device functioning as a PE but cannot be imported to OSPF. This is because the role of the router changes from a PE to an MCE after the vpn-instance-capability simple command is run in the OSPF process.


Solution: If the router needs to function as a PE, you need to run the undo vpn-instance-capability simple command on the router.

good post