Why cannot the backup information of a static route or a BGP route be generated after IP FRR is configured


IP FRR does not automatically take effect for iterated routes. Instead, an iterated route inherits the backup outbound interface and backup next hop of the route to the next hop that are generated through IP FRR. If the static route or BGP route is an iterated route and the IP FRR backup information of the next hop route is not generated, the backup information cannot be generated although the static route or BGP route matches the IP FRR policy.

Other related questions:
Why are all the next hop addresses in the BGP routing table displayed as 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 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.

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 the S series switches do not generate backup information for static routes or BGP routes after configuring IP FRRs
The iterative route does not apply the IP FRR configuration directly, but inherits next-hop route through the backup outbound interface and the backup next hop generated by IP FRR. Static route or BGP route If it is an iterative route and the next hop route does not generate backup information of IP FRR, static route or BGP route does not generate backup information even if it matches IP FRR policy.

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.

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