I ran into an issue where I couldn’t get R4 to use the OSPF route when configured for BGP synchronization. It had the correct AD, but wasn’t taking over from the iBGP route. I found an obscure rule in https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13753-25.html
“If the matching route is learned from an Open Shortest Path First (OSPF) neighbor, its OSPF router ID must match the BGP router ID of the iBGP neighbor.”
Turned out that in R2 the OSPF process wasn’t using the loopback interface for the router ID. When I corrected that and OSPF and BGP matched, the OSPF route was used in R4 and the problem was resolved.
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