From: David Luu (wicked01@xxxxxxxxxxxxx)
Date: Fri Jun 28 2002 - 18:38:49 GMT-3
sounds simple enough...
use route tags
have R2 set a tag for the 10.1.0.0/16 and have R3 block the tag going into
area 0
At 09:10 PM 6/28/2002 +0100, Peter Whittle wrote:
>Selectively blocking OSPF routes between areas
>----------------------------------------------
>
>I would like to pose a simple scenario to the group.
>
>There are 4 routers R1 .. R4
>
>R1 is injecting routes into RIPv2 say 10.1.0.0/16
>
>R2 is running RIPv2 on e0, it is also connected by e1 to OSPF Area 1 and
>must inject the routes learnt from RIP into AREA 1. There are other
>routers also connected to the ethernet segment in Area 1 again running
>OSPF. The routes injected by R2 into area 1 must be visible to these
>routers via OSPF.
>
>R3 has 2 ethernet interfaces e0 in OSPF Area 0, and e1 in OSPF Area 1.
>It must see the RIP routes injected into OSPF by R2 (ie 10.1.0.0/16).
>
>R4 in connected to the ethernet in Area 0 and is also running OSPF and
>is outside of your control.
>
>STOP the RIP routes that were injected by R2 from being seen in Area 0.
>(i.e. block the 10.1.0.0/16 route)
>
>You may only program routers R2, & R3 to achieve this.
>
>
>Any thoughts, ideas, solutions?
>
>
>I have one solution in mind but it is not very elegant. I will share
>this next week when you have had time to think about the problem.
>
>
>------------
>
>A distribute-list applied to R3, an ABR, will of course not work. (When
>the 10.1 route reaches R3 it is in an LSA. If we apply the distribute-
>list x in, it will only block the route going into R3's routing table,
>it will not prevent the LSA from being sent on to R4. We are not
>permitted to change the other routers in Area 0 so we can not use the
>conventional approach of applying the distribute-list x in to each of
>the routers in Area 0.
>
>If we apply a distribute-list x out to the ABR it will again have no
>impact on the LSA advertising the 10.1 route into Area 0.)
>
>==========================
>
>May enlightenment be yours.
>
>Peter
>
>--
>Peter Whittle
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