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Prefer OSPF external type 2 route over intra area

bcbvale
Level 1
Level 1

I need to have a router prefer an external type 2 over a intra area route in OSPF. Any ideas on how this can be done for a specific link or route?

bcbv

2 Replies 2

ERIK LAWAETZ
Level 1
Level 1

To persuade the router to do that you'd have to change the administrative distance (AD) of the particular route/link in the router.

For OSPF you can change the AD for ALL routes inside the router using the distance ospf command:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt2/1cfospf.htm#1001411

But that's hardly what you're looking for, since that applies to all and not a single route.

Similarly you could in theory filter based on source of the route based on the OSPF router originating the routes in question:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt2/1cfindep.htm#1001373

But that too probably doesn't achieve what you want.

My best guess would be to use policy routing:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fipr_c/ipcprt2/1cfindep.htm#1001398

though that's pretty close to just using a static route.

mark-obrien
Level 4
Level 4

OSPF will always prefer an internal route, either intra-area or inter-area, over a external type-2 route. Your best bet, if you have control over the route in question, is to have the external type-2 route changed to a type-1 route. Even then, you will need to make sure the total cost of the route is less than the total cost of the itra-area route.

Good luck.

Mark

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