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

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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.

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.

On S series switches, how long does it take for BGP routes to expire after the static routes imported by BGP expire
If the static routes imported by an S series switch become invalid, the routes imported in the BGP routing table will be invalidated. The route imported through the network command must be active in the local routing table. Otherwise, it cannot be imported in the BGP routing table.

Why cannot OSPF on S series switches import BGP routes
Question: Why cannot OSPF import BGP routes? Answer: As defined in RFC 1364, routes learned via IBGP must not be imported into OSPF. That is, OSPF cannot import IBGP routes. PEs can import IBGP routes. Most VPNv4 routing tables contain BGP routes, but the routes cannot be imported into OSPF processes. This is because the vpn-instance-capability simple command is configured in the OSPF processes. After the command is configured, the PE role is disabled on a device and the device acts as an MCE. To enable the PE role on a device, run the undo vpn-instance-capability command.

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