From: John Neiberger (neiby@xxxxxxxxxx)
Date: Sun Nov 04 2001 - 03:48:43 GMT-3
Yes. I only did that because it was suggested a few times in the list
archives. It seems to me that it ought to be irrelevant because that
loopback network address should just be used as a default network when
advertised to C, right? 30.0.0.0/8 is a dummy network that doesn't exist
elsewhere in the network.
I can see that it is a candidate GOLR on B as well but since I have a
0.0.0.0/0 route available on B it ought to be taken. As you can see from
the output, that default route is taken when I try to ping 20.1.1.1. After
I add the default-network command the router will no longer use the route
available to it in the routing table. This just doesn't make sense to me.
If the route is there--especialy since ip classless is configured--that
route should be taken.
Regards,
John
On Sun, 04 Nov 2001 01:41:42 -0500, Manny Gonzalez wrote:
| Have you tried NOT using a default-network that points to a LOOPBACK?
|
| John Neiberger wrote:
| >
| > I'll start with the original scenario that worked so I can show you
where I
| > began before I show you what I'm trying to accomplish now. There are
three
| > relevant routers here:
| >
| > A----(ospf)----B----(rip)-----C
| >
| > A originates a default route to B and I use default-information
originate in
| > the RIP config to pass 0.0.0.0/0 to C. This works well. Then I took
RIP
| > away and tried this with IGRP and ip default-network.
| >
| > This took some tweaking before I could get B to originate default
route to
| > C with IGRP. Is it just me or did Cisco seem to make this very
| > user-unfriendly?? Unbelievable. This is *so* easy with other
protocols.
| > Anyway...
| >
| > In the first scenario, B has a single gateway of last resort:
0.0.0.0/0 via
| > router A. Beautiful. In the second scenario I end up with two
candidate
| > GOLRs but neither is picked and routing breaks!
| >
| > This makes *zero* sense to me. If ip classless is configured and
still
| > have 0.0.0.0/0 in my routing table then B should route all packets with
| > unknown destinations to A, right?? Well, it's not working and I can
| > consistently recreate it.
| >
| > If I remove the ip default-network statement routing works but then C
has no
| > default route.
| >
| > What could be wrong here? For grins, I'll paste in some command output
to
| > show you what I mean. R4 is "Router B" in the above scenario.
| >
| > Gateway of last resort is 152.1.3.2 to network 0.0.0.0
| >
| > 152.1.0.0/16 is variably subnetted, 2 subnets, 2 masks
| > O IA 152.1.1.0/25 [110/74] via 152.1.3.2, 05:19:53, Serial0
| > C 152.1.3.0/30 is directly connected, Serial0
| > 130.1.0.0/16 is variably subnetted, 9 subnets, 2 masks
| > I 130.1.3.0/24 [100/1188] via 130.1.4.2, 00:00:28, TokenRing0
| > I 130.1.2.0/24 [100/1188] via 130.1.4.2, 00:00:28, TokenRing0
| > I 130.1.1.0/24 [100/1188] via 130.1.4.2, 00:00:28, TokenRing0
| > O 130.1.0.0/22 is a summary, 05:19:54, Null0
| > I 130.1.7.0/24 [100/1188] via 130.1.4.2, 00:00:29, TokenRing0
| > I 130.1.6.0/24 [100/1188] via 130.1.4.2, 00:00:29, TokenRing0
| > I 130.1.5.0/24 [100/1188] via 130.1.4.2, 00:00:29, TokenRing0
| > O 130.1.4.0/22 is a summary, 05:19:54, Null0
| > C 130.1.4.0/24 is directly connected, TokenRing0
| > C 30.0.0.0/8 is directly connected, Loopback1
| > O*N2 0.0.0.0/0 [110/1] via 152.1.3.2, 05:19:56, Serial0
| > R4#ping 20.1.1.1
| >
| > Type escape sequence to abort.
| > Sending 5, 100-byte ICMP Echos to 20.1.1.1, timeout is 2 seconds:
| > !!!!!
| > Success rate is 100 percent (5/5), round-trip min/avg/max = 24/28/40 ms
| > R4#
| >
| > After I add ip default-network 30.0.0.0:
| >
| > Gateway of last resort is not set
| >
| > 152.1.0.0/16 is variably subnetted, 2 subnets, 2 masks
| > O IA 152.1.1.0/25 [110/74] via 152.1.3.2, 05:21:19, Serial0
| > C 152.1.3.0/30 is directly connected, Serial0
| > 130.1.0.0/16 is variably subnetted, 9 subnets, 2 masks
| > I 130.1.3.0/24 [100/1188] via 130.1.4.2, 00:00:32, TokenRing0
| > I 130.1.2.0/24 [100/1188] via 130.1.4.2, 00:00:32, TokenRing0
| > I 130.1.1.0/24 [100/1188] via 130.1.4.2, 00:00:32, TokenRing0
| > O 130.1.0.0/22 is a summary, 05:21:19, Null0
| > I 130.1.7.0/24 [100/1188] via 130.1.4.2, 00:00:34, TokenRing0
| > I 130.1.6.0/24 [100/1188] via 130.1.4.2, 00:00:34, TokenRing0
| > I 130.1.5.0/24 [100/1188] via 130.1.4.2, 00:00:34, TokenRing0
| > O 130.1.4.0/22 is a summary, 05:21:20, Null0
| > C 130.1.4.0/24 is directly connected, TokenRing0
| > C* 30.0.0.0/8 is directly connected, Loopback1
| > O*N2 0.0.0.0/0 [110/1] via 152.1.3.2, 05:21:22, Serial0
| > R4#
| > R4#ping 20.1.1.1
| >
| > Type escape sequence to abort.
| > Sending 5, 100-byte ICMP Echos to 20.1.1.1, timeout is 2 seconds:
| > .....
| > Success rate is 0 percent (0/5)
| > R4#
| >
| > Any help would be appreciated. I'm about to swear off using IGRP and
EIGRP
| > for the rest of my life just on principle. :-)
| >
| > Thanks,
| > John
| >
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