all 3 locations are connected in dazy chain
A—B—C
A and B connected with fiber B and C connected thru fiber and this is thru dark fiber now at B location there is OSPF configured with back bone area on core and there is EBGP configured between B and C and at C end also OSPF configured at core level on backbone area 0 , now at B end OSPF is redistributed to EBGP also in this redistribution there are routes of A locations also learn and advertise to c location and this redistribution happen at C location to advertise c location network to B.
Now my question is how to Remove EBGP and setup complete network of B and C over OSPF routing protocol and what would be my option if i need to do everything with OSPF between B and C .
To transition from an eBGP-based setup to a purely OSPF-based configuration between Locations B and C, you’ll need to consider how routing information is propagated without the use of BGP. Here’s a high-level set of steps you can use to approach the redesigning of the network:
Establish OSPF Adjacency Between B and C
Configure a new OSPF adjacency between Location B and Location C over the existing dark fiber link. Ensure this link is added to the OSPF backbone area (Area 0) if possible, as this will simplify routing between all three locations (A, B, and C).
Remove eBGP Configuration:
Gradually phase out the eBGP configuration between B and C once you confirm that all required routes are advertised and reachable over OSPF.
Before removing eBGP completely, ensure that all routes from Location A and C are being advertised correctly through OSPF alone.
Testing and Verification:
Perform extensive testing to verify that all necessary routes are available end-to-end (A to C) with OSPF alone primarily using ping and traceroute, or other network tools you may have available.
This high-level approach allows for a smooth transition, ensuring minimal disruption and gradual phasing out of eBGP while maintaining optimal network performance. Does that make sense?