From: Daniel Keller (DMKeller@xxxxxxxxxxxx)
Date: Thu Sep 21 2000 - 12:08:57 GMT-3
Julie Ann,
The key to doing this is to make the default route different than what is in ro
uter B's routing table already. If you do this it should work:
In router A, add a loopback address different than the 172.17.X.X address. Mak
e it 10.1.1.1. Use what subnet mask you want. Then, use the command "ip defau
lt-network 10.0.0.0". Make sure that you do not use "ip default-metric 10.1.0.
0 or 10.1.1.0." If you do, a static route will be placed in the config. Also,
be sure that "ip classless" is done on router B. Let us know if this works.
Dan Keller
>>> "Connary, Julie Ann" <jconnary@cisco.com> 09/21/00 09:20AM >>>
Hi,
Can anyone post configs for the ip default-network method. I cannot seem to
figure it out. Thanks.
I re-read Caslow and he gives two options to solve this problem:
summarization with a static to null 0 and using ip defulat-network with
ip-classless. I got the first to work in the lab, no problem. The second
however is causing me problems.
I tried to make an ip default-network to 172.17.59.0 on the router a, but
what I got in the config was a static route:
router igrp 100
redistribute ospf 1 metric 64 10 255 1 1500
passive-interface Loopback5
network 172.17.0.0
!
ip classless
ip route 172.17.0.0 255.255.0.0 172.17.59.0
Then I tried to make and ip default-network to 172.17.0.0. now I have a
candidate default route in my routing table on router a, but
router b is not getting the default-route and I can still not get to the
172.17.59.0 networks in ospf:
version 11.2
no service udp-small-servers
no service tcp-small-servers
!
hostname r1
!
!
no ip domain-lookup
!
interface Loopback0
ip address 1.1.1.1 255.255.255.0
!
interface Loopback1
ip address 172.17.59.33 255.255.255.240
!
interface Loopback2
ip address 172.17.59.49 255.255.255.240
!
interface Loopback3
ip address 172.17.59.65 255.255.255.192
interface Loopback5
ip address 172.17.45.1 255.255.255.0
!
interface Ethernet0
no ip address
shutdown
!
interface Serial0
ip address 172.17.60.2 255.255.255.0
!
interface Serial1
ip address 193.1.1.1 255.255.255.0
!
interface BRI0
no ip address
shutdown
!
router ospf 1
redistribute igrp 100 metric 64 subnets
network 172.17.59.32 0.0.0.15 area 0
network 172.17.59.48 0.0.0.15 area 2
network 172.17.59.64 0.0.0.63 area 3
!
router igrp 100
redistribute ospf 1 metric 64 10 255 1 1500
network 172.17.0.0
!
ip classless
ip default-network 172.17.0.0
!
line con 0
line aux 0
line vty 0
line vty 1 4
!
end
routing table on router a:
Gateway of last resort is not set
1.0.0.0/24 is subnetted, 1 subnets
C 1.1.1.0 is directly connected, Loopback0
* 172.17.0.0/16 is variably subnetted, 5 subnets, 3 masks
C 172.17.60.0/24 is directly connected, Serial0
C 172.17.45.0/24 is directly connected, Loopback5
C 172.17.59.32/28 is directly connected, Loopback1
C 172.17.59.48/28 is directly connected, Loopback2
C 172.17.59.64/26 is directly connected, Loopback3
C 193.1.1.0/24 is directly connected, Serial1
routing table on router b:
Gateway of last resort is not set
172.17.0.0/24 is subnetted, 2 subnets
C 172.17.60.0 is directly connected, Serial0
I 172.17.45.0 [100/8976] via 172.17.60.2, 00:00:12, Serial0
I put the 172.17.45.0 loopback interface on router a, just to make sure I
was getting routes distributed via IGRP.
Can anyone post configs that work for the ip default-network method.
Thanks Julie Ann
At 04:52 PM 9/20/2000 -0700, mark salmon wrote:
>I still disagree with the blanket statement about static routes. If you
>want to summarize OSPF you have to use static routes (null 0). I still
>believe that you can do so as long as you are using summarization.
>
>One method that is recommended by Caslow is to use a static route to
>null 0 with the same mask as the IGRP net.
>
>For example, suppose the masks on the IGRP networks is /24, but it
>varies on the OSPF net.
>
>On the ASBR, you can do 172.17.x.0 255.255.255.0 null 0 (be careful
>here, if you have a dynamic route for x you will pass packets into a
>black hole, the key is to have good network design to prevent this). If
>you already have a 172.17.x.0/24 network, then I would create a class c
>subnet (e.g. 198.135.244.1/24) on a loopback interface, either
>redistribute it into IGRP or advertise it in IGRP. Then make it the
>default network for IGRP.
>
>Comments group (Flame jacket on for this).
>Mary Weidner wrote:
> >
> > All,
> >
> > I am working on a practice lab on one of the midwest channels racks and
> am having a problem with redistribution. Here's a sample config:
> >
> > Router A
> > !
> > router ospf 100
> > network 172.17.59.32 0.0.0.15 area 0
> > network 172.17.59.48 0.0.0.15 area 2
> > network 172.17.59.64 0.0.0.63 area 3
> > redistribute igrp 100 metric 64 subnets
> > !
> > router igrp 100
> > network 172.17.0.0
> > redistribute ospf 100 metric 64 10 255 1 1500
> >
> > Router B
> > !
> > router igrp 100
> > network 172.17.0.0
> > !
> >
> > Here's the deal, IGRP does not understand VLSM which is what is being
> used on router A with OSPF. From all the docs I've read, you would have
> to put in static routes on Router B to tell it how to get to those other
> subnets, except I'm not allowed to use static routes. The subnets in OSPF
> on Router A are not redistributing into IGRP. They come out as 172.17.0.0
> instead of whatever the real network number is.
> >
> > Here's the other thing I tried; I added these lines:
> >
> > Router A
> > !
> > router ospf 100
> > default-information originate always
> > !
> > router igrp 100
> > default-information allowed in 1
> > default-information allowed out 1
> > !
> > access-list 1 permit any
> >
> > Router B
> > !
> > router igrp 100
> > default-information allowed in 1
> > !
> > access-list 1 permit any
> >
> > The thinking here was to originate a default route (0.0.0.0) from
> Router A in OSPF and try to redistribute this into IGRP..... it didn't
> work. Maybe I just configured it wrong or maybe it's just not possible. I
> don't know. This is the second time I've attempted to get this working to
> no avail. Let me know if you have any ideas.
> >
> > Thanks,
> >
> > Tony Olzak
> >
> > BTW-I've just joined the list. I'm scheduled to take the test on Nov
> 19-20 in RTP.
> >
> >
> >
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