Question: OSPF, DDR, backup routes

From: Theodore TZEVELEKIS (theodore_tzevelekis@xxxxxxxxx)
Date: Wed May 16 2001 - 20:43:37 GMT-3

   
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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