https://38a8db03.aww-3cz.pages.dev/tags/stub/ Recent content in Stub on Aaron's Worthless Words Hugo en Sun, 20 Jun 2010 00:00:00 +0000 https://38a8db03.aww-3cz.pages.dev/posts/2010/06/route-notes-ospf-filtering-and-summarization/ Sun, 20 Jun 2010 00:00:00 +0000 https://38a8db03.aww-3cz.pages.dev/posts/2010/06/route-notes-ospf-filtering-and-summarization/ <p>Feel free to correct all this stuff.  Additions are also welcome.</p> <p><strong>Study Questions</strong></p> <ul> <li>How do I keep an area route from reaching a router in that area?</li> </ul> <p>You don’t.  That defeats the whole purpose of having the topology database on every router.  If you filtered one route from a router, there’s no way that SPF could calculate routes correctly.</p> <ul> <li>Fine, then.  Where do I filter routes?</li> </ul> <p>You filter routes on an ABR or ASBR.  Since routers only have the whole topology for their area, it’s safe to filter routes from another area or from a redistributed routing protocol.  On a more technical note, you’re filtering type-3 LSAs on an ABR and type-5 LSAs on an ASBR.</p>