Re: How to filter external OSPF routes from database ?

Just an untested idea, Run two ospf processes on R3 else you can use
summary-add or distribute-list out on ASBR.

On Tue, Nov 10, 2009 at 11:37 AM, Tomasz Solski <tom.solski_at_gmail.com>wrote:

> Hi, I viewed the video but still can not filter external routes. I built
> the
> lab in dynamips exactly as shown in the presentation (5 mins 30 sec):
>
> R1------area1-----R2-----area0------R3--------area2--------R4
>
> R1 advertises 1.0.0.0/8 into area1.
> On R3 I added static route "ip route 1.0.0.0 255.0.0.0 Null0"
>
> All works as expected: 1.0.0.0/8 will not show on R4.
>
> But if R1 redistributes 1.0.0.0/8 with command "redistribute connected
> subnets" then the route 1.0.0.0/8 will show show as E2 on R4. R4 will not
> be
> able to ping 1.1.1.1 but it still shows in the routing table.
>
> My question is then, how to prevent external route redistributed in Area1
> from showing in any other area.
>
>
>
> > > Hi,
> > >
> > > Take a look at the following free class on demand and you will master
> > that
> > > topic in minutes:
> > >
> > >
> >
> http://www.micronicstraining.com/videos/filtering-ospf-prefixes-section-1.zip
> > >
> > > HTH,
> > > --
> > > Piotr Matusiak
> > > CCIE #19860 (R&S, SEC)
> > > Technical Instructor
> > > MicronicsTraining.com
> > >
> > > If you can't explain it simply, you don't understand it well enough -
> > > Albert Einstein
> > >
> > >
> > > 2009/11/9 Tomasz Solski <tom.solski_at_gmail.com>
> > >
> > > > How to filter external OSPF routes from database ?
> > > >
> > > > Here is an example:
> > > >
> > > > R1------Ar0------R2------Ar1-------R3
> > > >
> > > > R1 redistributes routes into Area 0.
> > > >
> > > > I want ot configure R2 so R3 does not have a specific external route
> in
> > > its
> > > > database.
> > > >
> > > > I tried on R2:
> > > > <<<
> > > > ip prefix-list R1toR3 seq 5 deny 1.1.12.0/24
> > > > ip prefix-list R1toR3 seq 10 permit 0.0.0.0/0 le 32
> > > > router ospf 1
> > > > area 1 filter-list prefix R1toR3 in
> > > > >>>
> > > >
> > > > but it looks like external routes can not be filtered with filter
> list.
> > > As
> > > > soon as I advertise 1.1.12.0/24 on R1, instead of redistributing it,
> > it
> > > > disappears from R3's database and routing table.
> > > >
> > > >
> > > > Blogs and organic groups at http://www.ccie.net
> > > >
> > > >
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Received on Tue Nov 10 2009 - 15:53:02 ART