From: ccie2be (ccie2be@nyc.rr.com)
Date: Sun Jun 26 2005 - 22:18:15 GMT-3
Hi guys,
Thanks for getting back to me on this.
So, here's my summary from your posts:
1. The area X range command can only summarize internal ospf routes
regardless of what type of stub network is configured.
2. Configuring any type of stub area doesn't prevent the use of the area X
range command. The command can still summarize the ospf routes internal to
that area.
Do you all agree with this?
Tim
-----Original Message-----
From: George Cassels [mailto:glcassels3@nc.rr.com]
Sent: Sunday, June 26, 2005 8:45 PM
To: 'Sila Moni'; 'ccie2be'; 'Group Study'
Subject: RE: using nssa and area X range together
Sila,
Take a look at my response to Tim...I used the summary-address
command and it aggregated the routes going to another ospf area 0
router.
George
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Sila Moni
Sent: Sunday, June 26, 2005 7:31 PM
To: ccie2be; Group Study
Subject: Re: using nssa and area X range together
You can't summarize external routes (I don't have a
rack to lab it out to confirm). Since R2 has only one
exit point, you can use LSA 3 filter to deny all
routes except for the default prefix. Example:
ip prefix-list LSA-FILTER deny x.x.x.x/24
ip prefix-list LSA-FILTER permit 0.0.0.0/0 le 32
!
router ospf 1
area 1 filter-list prefix LSA-FILTER in
--- ccie2be <ccie2be@nyc.rr.com> wrote:
> Hi guys,
>
> This is an interesting scenario - at least I hadn't
> thought much about this
> previously.
>
> Let's say you have this topology:
>
> IGP R1 nssa R2 area 0 R3
>
>
> R1 is redist routes from another IGP into OSPF. Can
> I use the area X range
> command on R2 to summarize routes learned from the
> IGP redist into the nssa
> area so that the backbone doesn't have all those
> specific routes from the
> other routing protocol?
>
>
> And, more generally, do I need to be concerned about
> any restrictions on
> using the area X range command to summarize routes
> into the backbone area
> depending upon what type of stub area is configured?
>
> What I find interesting about this scenario is that
> typically when I think
> about what type of stub area to configure, I'm
> concerned about what routes
> are advertised into the stub area from the backbone.
>
> In this scenario, it's just the opposite. Here the
> concern is what routes
> area advertised from the stub area into the backbone
> area.
>
> (I don't have access to any routers at the moment to
> lab this up.
>
> TIA, Tim
>
>
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