OSPF has the behaviour of sending routes as LSAs and not copies of routing table. So if you put a output filter to filter routes in router B, you will still see the LSAs in A and C, and routes wont get filtered. SO you might want to put a input filter list at C to filter routes from coming into the routing table of C. Still you will see the LSA in the database of C.
configure a distribute-list in C
router ospf 10
distribute-list 10 in
acces-list 10 permit
permit those networks you want to see, the rest will be denied and wont be in the routing table.
Funny this should come up, I was just talking with someone about this is morning.
From Cisco: "OSPF routes can't be filtered from entering the OSPF database. The distribute-list in command only filters routes from entering the routing table, but it doesn't prevent link-state packets from being propagated.
The command distribute-list out works only on the routes being redistributed by the autonomous system boundary routers (ASBRs) into OSPF. It can be applied to external type 2 and external type 1 routes, but not to intra-area and inter-area routes."
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