Re: How to filter external OSPF routes from database ?

summ-add should work for LSA 5&7. in your case. R2 is converting LSA 7 into
LSA 5.

On Tue, Nov 10, 2009 at 7:27 PM, Tom Solski <tom.solski_at_gmail.com> wrote:

> Thanks Miroslav. Summary address on R2 works if area 1 is configured as not
> so stubby (NSSA). I am referring to this topology:
>
> R1------area1-----R2-----area0------R3--------area2--------R4
> R1 redistributes external 1.0.0.0/8 into area1.
>
> IOS appears to me really inconsistent here. Why summary-address works for
> N2
> routes and does not for E2 routes?
>
>
> -----Original Message-----
> From: Miroslav Kosut [mailto:miroslav.kosut_at_gmail.com]
> Sent: 10-Nov-09 16:22
> To: Tomasz Solski
> Cc: Cisco certification
> Subject: Re: How to filter external OSPF routes from database ?
>
> Stubby area :-)
>
> External LSAs (LSA5) can be filtered on ASBRs using summary-address
> NET MASK not-advertise. I don't know about any other way of filtering
> them on ABRs except using stubby areas.
>
> Regards,
> Miroslav
>
> On Nov 10, 2009, at 10:15 PM, Martin Hogan wrote:
>
> > What does the Cisco Doc tell you about that command?
> >
> > Hint: It's only effective on a particular LSA type.
> >
> >
> >
> > On Tue, Nov 10, 2009 at 7:44 AM, Tomasz Solski
> > <tom.solski_at_gmail.com> wrote:
> >
> >> 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.
> >>
> >>
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Received on Tue Nov 10 2009 - 22:19:08 ART