OSPF Query

Unanswered Question
Apr 7th, 2008


R1---| |--R6


there are lo11 on R1 and Lo66 on R6 i need the traffic between them take the path R2,R5 All the routers are in Area 0

I can't use the cost command beacuse that will force all the traffic but i need the traffic between these 2 loopbacks only

Any help will be appreciated?

I have this problem too.
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Kevin Dorrell Mon, 04/07/2008 - 03:39

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


Kevin Dorrell Mon, 04/07/2008 - 06:11

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



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