From: Kirby, Ron (Ron.Kirby@xxxxxxxxxxxxx)
Date: Fri Dec 21 2001 - 14:33:30 GMT-3
The "area range" command will summarize a backbone net into an IGRP AS. I
did a lab similar to this 2 days ago. The IGRP AS was a /24 and the frame
network, which was the ospf area 0 was a /28. I also had /32's from some
loopbacks that had to go into the IGRP AS as well. I played with various
ways to do it. First, I had a Class C network hanging off another router,
so I created a default route to that classful network on the IGRP-only
router and I could ping everything in the OSPF system, even though the frame
and loopback addresses were not in the routing table. I suspect this would
not be acceptable though, as this is a "default-route", it just doesn't use
the quad-zero entry in the routing table, but it does work. Next I added
the "ip ospf network type" command to the loopbacks and used the "area
range" command at the redistribution point, summarizing the /28 to a /24.
The loopbacks appeared at the IGRP router as /24s, but not the /28s. I had
to add the null route to the config on the redistribution router (as
explained by Doyle in V1) and then it worked fine, both the loopbacks and
the frame network (as a /24) was in the IGRP routing table. But is that a
technical no-no, as it involves a "static route"? If this is a no-no, what
else can you do to get /28s into an IGRP AS using a /24??
Ron Kirby
CCNP, MCSE, CNA
Network Engineer
Getronics, Houston ESC
713-852-5567 / 832-256-5403
ron.kirby@getronics.com
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-----Original Message-----
From: Thomas Larus [mailto:tlarus@mwc.edu]
Sent: Friday, December 21, 2001 11:10 AM
To: ccielab@groupstudy.com
Subject: OSPF to IGRP redistrib - How to summarize area 0 routes?
I am working on basic everyday OSPF to IGRP redistribution. I was able
to use area range for the routes I needed to get down to /24 to match
the IGRP domains mask. But what if the scenario had been set up
differently, and I had had routes within area 0 that had to be
summarized to /24 to be redisted into IGRP? Area range summarizes
non-backbone areas INTO area 0. Summary-address only works on routes
redistributed INTO the OSPF domain. The experts all say that there are
two way to deal with the classless to classful redist problemstatic
routes and summarization. If it is stated that I cannot use static
routes, and the routes I need to summarize are within area 0, what do I
do?
I can design the network to make sure all the routes that need to be
redistributed from OSPF to a classfull routing protocol are in an area
other than 0, but what if I am given the situation I have set out?
A route-map comes to mind, but I dont see how I can summarize using a
route-map, although I can make it so that only routes with a certain
mask get redistributed.
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