Restrict OSPF routes

[sqambera]

Hello,

I am running OSPF on my routers. On Internal routers I want to stop receiving and forwarding any subnet information that are not directly connected to it. In other words I don't want any of my router with none of its interface in area 0 to have any route except the default route towards ABR/ASBR. Could somebody please let me know how to do that?

Thanks in advance,

Qamber

[sqambera]

Thanks for the reply. How could I run two areas between two ABR routers?

Regards,

Qamber

[Joseph W. Doherty]

You're already doing that, i.e. you have areas zero and one.

What I'm suggesting is both ABRs have two logical or direct physical links between; one in area zero the other in area one.

Once you also have an area one link between them, it would be an IA route, and depending on OSPF costing, the best path between them.  I.e. you shouldn't need to transit R1.

[Joseph W. Doherty · Accepted solution]

BTW, what I've suggesting I've done on production networks, to exactly avoid the situation you're trying to avoid.

I've done it both using physical links between ABRs and using "logical" links between ABRs.  The latter might be accomplished using VLANs and trunks, subinterfaces, or GRE/MPLS tunnels.  All you need is OSPF to "see" a better path between the two ABRs that doesn't transit another router.  The latter is also useful if you summarize address blocks to area zero as its traffic will not "know" where the closest ABR is for the destination network.

[Masoud Pourshabanian]

Good idea. It was helpful.

Best,

Masoud