Hello,
From your exhibit, I assume that R-C01 knows about the network 192.168.90.0/24 via OSPF only, and that the route is learned as external (redistributed). You have not indicated whether the route is advertised as External Type-1 or External Type-2.
In general, the OSPF can perform only equal-cost load balancing. That implicates that the R-C01 must consider both routes to the network 192.168.90.0/24 of equal cost, only then it will perform load balancing. In turn, that means:
- If the network is advertised as External Type-1 then the total metric of both routes must be equal, i.e.: the sum of link costs R-C01:RR01+RR01:RR02+RR02:R-C02+R-C02:R-BH-02+seed metric must be equal to the sum of link costs R-C01:R-BH-01+seed metric
- If the network is advertised as External Type-2 then the seed metric must be identical on both redistributing routers, and the cost to reach both ASBRs must be identical, i.e. R-C01:RR01+RR01:RR02+RR02:R-C02+R-C02:R-BH-02 = R-C01:R-BH-01
Obviously, you would need to manually modify the link costs to get the desired effect.
As a general rule, a routing protocol is responsible for populating the routing table with accurate and complete information about best paths to any reachable destination. However, what you want to do is basically traffic engineering, and that is out of scope of routing protocol competences. We can force a routing protocol to perform load balancing for a certain set of destinations but for more general deployments, we have to resort to specific traffic engineering mechanisms such as MPLS-TE.
Best regards,
Peter
