We're advertising the same /16 network via aggregate out two BGP routers. The /16 network is being learned by both routers via OSPF E2 routes. When R21 is up we'd like to prefer that path. Only use R11 when R21 is down.
Normalized
- R11 has a BGP AD 20 route. OSPF can't install the AD 110 route
- R21 has OSPF route AD 110 route. advertises aggregate to AS1
R21 Fails:
- R11 removes BGP AD 20 route, then OSPF AD 110 route installed, advertises aggregate to AS1
- R21 still has OSPF AD 110 route, link down can't advertise aggregate to AS1
R21 comes back up:
- R11 still has BGP AD 20 route and OSPF 110 can't install in route table
- R11 Since no OSPF route exists BGP can't advertise the /16 route
- Route never normalizes.
I'm pretty sure this is one of the non-deterministic scenarios with BGP but just looking for best options to overcome. ie exist-map.
