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OSPF redistribution in single process or multiple processes

see attached drawing for reference.  I have 3 sets of routers. r301/302 is in area 0 and 1, r11/12 is area 0 and r99/98 is area1.  I want to redistribute the specific area 1 routes showing below r98/98 only and deny everything else into area 0 on r301/302 and only send default route into area .  My question is can i use a single OSPF process on r301/302 or do I need to configire 2 different OSPF processes and redistribute from 1 to 0?  if only a single process is possible what would an example configuration look like?

All the links showing on the drawing are L3 point to point /30s.

Cisco Employee

Hi tporembski,

I reckon you want to redistribute address space in OSPF, right?

How are these routes known to r98? Are they directly connected or are known via a different protocol maybe static or any other dynamic routing protocol?

Can you explain what your objective is here? What is it that you're trying to achieve?



r98/99 is out of my management domain.  I am requesting the admin of those routers to send me a summary route/s that can include the address space  - to r301/302.  The P-toP links between r301/302 and r98/99 will be OSPF.  There is no other routing protocol besides OSPF in this entire infrastructure.  So on r98/99 they could be directly connected, or static or known via OSPF internal to those routers.

In the end the objective is to be able to advertise a default route from r301/302 into r98/99 and from r98/99 only allow the - to r301/302 and onto r11/12.  Hopefully that clarifies it.

if the redistribution is taking place on r98 then the LSA or route filtering would need to be done on the ASBR only since these routes would be flooded in the OSPF domain as type 5 or 7 depending on the area type and the filtering can be done on the originating router.

To only propagate a default route to area1 you can make it an NSSA with the option to advertise a default route incorporated in the config. This will allow redistribution on r98 and will also allow the flooding of a default route to the area. A quick read on area types or the NSSA area types will help you do this. Then again to make this happen we would need to have the area type consistent throughout area1 and that includes the routers which are not under your authoritative control.