Here's the situation â¦. I have a remote router acting as an ABR for both OSPF area 5 and area 0. In area 5, I have a network address of 10.1.2.0 /24 that I want to keep advertising in area 5 but not to have the network advertised via area 0. The reason for this is the network is a conflict that can't be removed at this time.
What's easier, to try to filter on this specific router or to filter on the far end router, that is a backbone router. Any suggestions? i.e route map vs. distribute list vs. pre-fix list?? I would appreciate a sample config as to how this could be done.
have the net 10.1.2.0/24 advertised in area 5.
At the ABR(5,0) you can filter it by using an area filter-list.
or area 5 range 10.1.2.0 255.255.255.0 not-advertise under router ospf process on ABR(0,5).
Avoid to have this subnet redistributed into OSPF because LSA type 5 cannot be filtered out of the OSPF database.
Hope to help
All will depends on the type of route this network appears as and the types of areas you are using.
In the best case if it appears as a type 3 . Then you can use prefix lists to filter on area. When the routes appear as externals or intra area routes your options are very limited.