OSPF Update Question

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Feb 4th, 2008
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Hi


Could some one help me with the following. Basically I'm looking to make an update on the metric for an OSPF process on router. I assumes I will need to clear the routing table after making the change, but will I need to clear the routing process of every other router aswell? Or will all the other routers pick up the new metric and automatically adjust their routes if this is the best metric?


Thanks

Dan

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Kevin Dorrell Mon, 02/04/2008 - 08:07
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You shouldn't have to clear anything. If you are modifying the cost of a link, the OSPF should immediately generate an LSA for that link with its new value and flood it throughout the area. All the routers will see the LSA, put it in their database, and re-run the SPF calculation.


If you want to check that out, put debug ip routing on eachy router in the area, and watch what happens as you modify the link cost.


Same argument is true if you are talking about the metric on external routes. OSPF is pretty good about detecting changes and propagating them.


The only time I have seen a problem with propagation was in redistributing with a route map that sets the metric, and changing the route map on the fly. Then I had to clear the routes at the ASBR. Other than that, I don't know any cases. Does anyone else know any?


Kevin Dorrell

Luxembourg


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