Route filtering doesnt work !!!

Unanswered Question
May 9th, 2010
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Hello everyone ,

I want to filter some routes with OSPF protocol ,I know that with OSPF i should do that on ABR or ASBRs but the problem is that when i configure route filtering to filter LSA type 3 ,instead of filter just one or two routes it filters all type 3 summery routes ,here is the configuration :

I have two routers R1 and R2 ,R1 is ABR with two areas attached to it ,i want to filter network from area 1, here the configs but it doesn't work ...

ip prefix-list filter seq 5 deny

ip prefix-list filter seq 10 permit le 32

router ospf 1

area 1 filter-list prefix filter out





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Peter Paluch Sun, 05/09/2010 - 22:54
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  • Cisco Employee,

Hello Omid,

Can you please double-check your configuration? I have just tried replicating the same problem using the same commands you have used, and for me, the filtering works as expected - the network in area 1 is not visible in the backbone, another networks from area 1 are advertised correctly.

Perhaps you could also post the configuration of your ABR.

Best regards,


Omid Almasieh Mon, 05/10/2010 - 00:20
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Hi peter

thanks for your quick reply ,the configuration that i wrote was the exact configs that i did on ABR router !!! would u plz let me know the version of IOS that u'v tested with ?

Warm regards ,


Peter Paluch Mon, 05/10/2010 - 00:24
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  • Cisco Employee,

Hi Omid,

IOS version: C2691-ADVIPSERVICESK9-M, Version 12.4(25c)

Let's have a look at your configuration, OK? Can you post the relevant sections here? And also, it would be helpful to see the output of the show ip ospf database summary output on the ABR.

Best regards,



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