From: Roman Rodichev (rodic000@xxxxxxxxxxx)
Date: Wed May 16 2001 - 22:17:30 GMT-3
you got a problem in your first paragraph. You can exchange routes between
non-backbone areas. Area1 will never send routes to Area2, they will first
be sent to area 0
and by they way! Now that I think about it, even if you run ospf demand
circuit between R1 and R3, ISDN will always stay up. That's because you will
have a virtual link between Area1 and Area0 traversing it.
Can you post your configs? I want to look at your BGP configs... just
curious about your "dirty solution"
>From: "Theodore TZEVELEKIS" <theodore_tzevelekis@yahoo.com>
>To: "Roman Rodichev" <rodic000@hotmail.com>, <ccielab@groupstudy.com>
>Subject: RE: Question: OSPF, DDR, backup routes
>Date: Thu, 17 May 2001 02:59:58 +0200
>
>I agree. With the virtual-link down, you have no intra-area route exchange.
>However, R2 also belongs to area 2 so it can still exchange routes with R3.
>One can imagine that we may be running some other protocol beyond R2-e3...
>that's another story. The issue here is how will a default route get
>installed in R2's table.
>
>ospf demand-circuit is probably THE solution. I mean I don't see any way it
>shouldn't work. I've done setups with OSPF-DDR before and they work fien
>(except when combined to multiple dialer profies between two same peers
>used
>as backups... but that's another story ;-) But! I don't want to run ospf
>over the ISDN. That would mean extending area0 or area 2 over the ISDN.
>Which does not fall within the specs that I have defined for myself ;-)
>
>I just want to try to find a solution with this data. So far I haven't been
>able to. And I'm beginning to lose hope :-(
>
>The only workaround I found was to use my BGP to inject the route (yes I'm
>running BGP over the whole thing as well) but
>1. This is not a proper solution (I want to use my OSPF network to do it).
>2. Last but not least: As soon as R2 gets a route from BGP, it will
>regerate
>a default route back into R3, thus overriding the floating default pointing
>to the ISDN and eclosing it into a loop (R2->R3 and R3->R2).
>
>In this scenario, the only solution I found is to generate the default
>route
>on R1, then just advertise it to R3 through R2 (thus not generate it
>locally
>on R2). This way, when the link goes down, R2 loses its own default, gets
>one from the BGP pointing to R3 and does not regerate one.
>
>But as I said, this is a "dirty" solution. I don't like it.
>
>Any comments?
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
>Roman Rodichev
>Sent: Thursday, May 17, 2001 2:36 AM
>To: ccielab@groupstudy.com
>Subject: Re: Question: OSPF, DDR, backup routes
>
>
>Very nice! I like it. But you can't do it.
>
>As soon as R1-R2 connections is gone, Area 1 and Area 2 need some way of
>connecting to area 0. You can only do it with a virtual link. But virtual
>link will never run over the interface that is not running OSPF :)
>
>try enabling ospf demand-circuit on the bri and tell us how it works out
>
>
> >From: "Theodore TZEVELEKIS" <theodore_tzevelekis@yahoo.com>
> >Reply-To: "Theodore TZEVELEKIS" <theodore_tzevelekis@yahoo.com>
> >To: "ccie-groupstudy" <ccielab@groupstudy.com>
> >Subject: Question: OSPF, DDR, backup routes
> >Date: Thu, 17 May 2001 01:43:37 +0200
> >
> >Hi all,
> >
> >I've been trying to find a way to solve a very specific problem...
>wihtout
> >any luck:
> >
> >You have 3 routers running OSPF:
> >R1 (e0-area0, e1-area1, bri1 -> R3, virtual-link to R2)
> >R2 (e0-area1, e1-area2(nssa), e3-area1, virtual-link to R1)
> >R3 (e0-area2(nssa), BRI1 -> R1)
> >
> >OSPF is NOT running on ISDN.
> >I inject a default route from R2 into area 3 therefore to R3, pointing to
> >itself (R2) - default-information yada yada.
> >
> >Now what I want, is with just one default on R3, and statics on R1
> >(floating
> >in both occasions) to be able to access R2-e3 through the ISDN in the
>event
> >of (R1-e1)<->(R2-e0) failure.
> >
> >What this means is that I have to somehow inject a default route into R2
> >when the ISDN comes up (Reminder: in normal circumstabnce, R2 is
>injecting
> >a
> >default route into R3). Furthermore, OSPF does NOT redistribute static
> >default routes. The only way I have found so far is to actually generate
>a
> >default-info yada yada on R3 when the link comes up. BUT! as soon as R2
> >receives this, it, in turn, generates a new default-info and injects it
> >back
> >into R3.
> >
> >Also, as the virtual link is down, I have to find a way to inject that
> >route
> >into the OSPF neighbors in area 1 hanging out of R2-e3.
> >
> >Any ideas?
> >
> >Thanks
> >
> >Theo
> >
> >
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