R1 is connected to both of R2,R3 and R6 connected to both of R5,R6

I think you will have to do this with a policy route.

I don't think you can do it with OSPF. The reason is that, within a single area, the OSPF database is unaware of the cost of individual prefixes. It only knows about the cost of the links. So what is valid for one prefix is valid for all of them.

Kevin Dorrell

Luxemboueg.

but how can i use the cost for individual Prefix

As far as I know, there is no way you can within an area. The cost is the cost of a link, and applies to all prefixes. OSPF is link-state, and so it only knows about links. The cost of each link is the same for all prefixes.

If you have external routes, then you can set the cost at the ASBR. However, even then you cannot differentiate the cost by prefix.

The LSA carries a cost for a link, but says nothing about each prefix.

Kevin Dorrell

Luxembourg