[j-nsp] Problems with OSPF stub area (Juniper and Cisco)
Fri, 8 Nov 2002 10:19:15 -0500
>> I suggest that you are better off having the routes. Can you add a
>> /32 from the range to a loopback somewhere? More importantly, why do
>> you need this route in OSPF if there are no destinations from it in
>> the area?
> I'm sorry but I don't understand. There is a /25 which belongs to
> that area and it doesn't show up in the forwarding table. That's
> the problem I have. I'm sure it'll go away when somebody checks
> the Ciscos configuration.
You're trying to get an ABR to "coalesce" (i.e. summarize, or
aggregate, but coalesce is the OSPF RFC term) routes. In other words,
you want to have multiple longer-mask routes in the range
188.8.131.52/25, in the stub area, but you only want to see the
coalesced (or "aggregated") route outside the area.
Earlier in this thread, when I asked if the ABR actually /had/ any
longer-mask routes in the range, you said it did not. We only coalesce
routes if there are routes to coalesce. If there are no more specific
OSPF routes in the area to coalesce, then there should be no need for
the /25 route in OSPF either, so we don't generate it.
So, I asked why you need such a route to be in OSPF in the first place.
If you do, I suggested that you should somehow ensure that there really
is a more specific route from the range in the area. Otherwise, you
should be looking at either exporting a route into OSPF, or perhaps you
are also running BGP, and you could deal with this route there.
Sorry if my use of the word "coalesce" is confusing. People often call
it summarizing, but that's not accurate when discussing OSPF, b/c it
refers to generating type 3 and type 4 LSAs for other areas, which does
not imply aggregation.