[j-nsp] ospf import policy

[Stacy W. Smith]

On Oct 25, 2008, at 8:08 AM, Daniel Roesen wrote:

> On Sat, Oct 25, 2008 at 05:52:44PM +0500, Andrew Jimmy wrote:
>> To keep consistency of ospf database; we don't use import policy.  
>> If we
>> don't need import policy for ospf protocol why the heck juniper  
>> developers
>> are giving us an option to configure it. Can someone please write  
>> the usage
>> of import policy for OSPF protocol.
>
> You misunderstood what the import policy chain does. It does NOT
> influence OSPF's database, but only the acceptance of OSPF routes into
> the local RIB. So LSAs not accepted by the import chain are still
> properly forwarded to other OSPF neighbors, maintaining the consistent
> database in all OSPF nodes.
>
> http://www.juniper.net/techpubs/software/junos/junos91/swconfig-routing/configuring-ospf-routing-policy.html
>
> "OSPF import policy allows users to define policy to prevent adding  
> OSPF
> routes to the routing table. This filtering happens when OSPF installs
> the route in the routing table. You can filter the routes, but not LSA
> flooding."

This is all true, but there's an additional clarification. Only the  
routes that were learned via external LSAs can be influenced with  
import routing policy. The routes learned via internal LSAs can not be  
prevented from being installed in the RIB.

--Stacy