Why cannot OSPF import BGP routes

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As defined in RFC 1364, 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 device changes from a PE to an MCE after the vpn-instance-capability simple command in run in the OSPF process.

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

Other related questions:
Why cannot OSPF import BGP routes
As defined in RFC 1364, 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 device changes from a PE to an MCE after the vpn-instance-capability simple command in run in the OSPF process. Solution: If the device needs to function as a PE, you need to run the undo vpn-instance-capability command on the device.

Why routes cannot be imported when AS numbers on the BGP/MPLS IP VPN are the same
When the AS number in the Update message to be received by the EBGP-enabled device is the same as the AS number on the device, the device does not receive the Update message. This prevents routing loops. In some scenarios, the device needs to receive a Update message that carries the same AS number as the AS number on the device. In Hub and Spoke networking, when the Hub-PE and Hub-CE use EBGP, the Update message received by the Hub-CE contains the AS number of the Hub-PE. To prevent the Hub-PE from discarding such Update message, run the peer allow-as-loop command to set the number of times for the repeated AS number.

Why are all the next hop addresses in the BGP routing table displayed as 0.0.0.0 after BGP imports routes from other protocols
Only routes that exist in the Border Gateway Protocol (BGP) routing table can be imported by the BGP. When importing such routes, BGP does not add new routes, but increases the reference count based on the routing table.

Why cannot an OSPF route that exists in the LSDB be found in the routing table
Perform the following steps to solve this problem: Check whether the IP address is valid. Check whether the forwarding address is known and reachable. Check whether the routes are summarized or redistributed correctly. Check whether different masks or IP addresses are used in the Peer-to-peer (P2P) connection. Check whether route lists are advertised. Check whether the backbone area is disconnected. Check whether OSPF is enabled on the secondary address but not on the primary address. Parent topic: IP Routing

Can OSPF import IBGP routes
In V200R001C00, open shortest path first (OSPF) cannot import Internal Border Gateway Protocol (IBGP) routes. Starting from V200R001C01, the OSPF protocol can import IBGP routes. By default, the OSPF protocol does not import IBGP routes. However, OSPF can import IBGP routes on Multi-VPN-Instance CE (MCE) devices. You can run the vpn-instance-capability simple command for OSPF processes to disable route loop detection and directly calculate routes.

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