Core Issue
Route redistribution is used to propagate routes learned using one protocol into another routing protocol. When Intermediate System-to-Intermediate System (IS-IS) is redistributed into Open Shortest Path First (OSPF), some IS-IS routes may not be redistributed successfully. Specifically, routes advertised using IS-IS on the redistributing router are not redistributed. This behavior is expected. If a directly connected network is also advertised by IS-IS, the route is entered into the local routing table as a connected route and not as an IS-IS route. While redistributing IS-IS into OSPF, these directly connected routes are not injected into OSPF.
Resolution
To redistribute connected routes, marked as C in the routing table, perform these steps:
- Configure an OSPF routing process by issuing the router ospf command.
- Redistribute the connected routes into OSPF by issuing the redistribute connected command.
For more information, refer to Redistributing Connected Networks into OSPF.
