His pings are definetly going to the loopback on Router B (R4) and are probably being load balanced over the 0/0 [!.!.!.]. Use ip default-network and point it out the interface you really want traffic to go to by default. If you don't want R4 to use the default, then apply a static default on all your other routers. Otherwise you run the risk of load balancing through the loopback (?). I'm not near any routers atm so I can not verify this.
Ip default-network 152.1.3.0 WAYNE BAETY, MCSE, A1C, USAF Network Systems Trainer -----Original Message----- From: Chuck Larrieu [mailto:[EMAIL PROTECTED]] Sent: Monday, November 05, 2001 8:09 AM To: [EMAIL PROTECTED] Subject: Re: Weirdness with OSPF-->IGRP and Default Routes [7:25216] John, it occurs to me that the other possibility is that your pings are getting out, but not getting back. On the surface, it would appear that is not the case because in part one of your scenario, you can successfully ping. However, it is possible that in doing what you did in setting up the default network, you broke something else such that the return route does not exist? just because you can see me, it does not automatically follow that I can see you. what do traceroutes reveal about where the breakdown occurs? How about an extended ping, using a different interface as the source address? Chuck ""John Neiberger"" wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > You're reading it correctly. The real problem isn't with router C. Using > either of the methods I tried it learns a default route from B. The real > problem is that as soon as I add a default-network command to router B (so > that it originates a default to C) default routing breaks. > > Others keep pointing out that having a loopback address as a default network > creates a blackhole. In this case I'm using a dummy network that does not > exist elsewhere so it won't create a black hole. > > In fact, when ip packet debugging is turned on the packets are unroutable. > This makes no sense to me since a quad-zero default exists in the routing > table. With ip classless nothing should be unroutable. Very weird. I must > be missing something... > > You think this is weird, though, you ought to see the lab setup I'm using to > test this. At the moment I have six routers running a combination of IS-IS, > BGP, OSPF, and IGRP. :-) I'm a glutton for punishment! > > Regards, > John > > On Sun, 4 Nov 2001 11:52:26 -0500, Chuck Larrieu wrote: > > | if I am not mistaken, the default network has to be "learned" via IGRP, > and > | cannot be a connected interface. If I am reading your outputs correctly, > | your default network is a connected interface. > | > | am I misreading which router is the source of the pings? > | > | Chuck > | > | > | ""John Neiberger"" wrote in message > | [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > | > I posted this to the ccie list as well. I'm hoping someone has run > across > | > this before. > | > > | > 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 > | > > | > > | > > | > > | > > | > > | > _______________________________________________________ > | > Send a cool gift with your E-Card > | > http://www.bluemountain.com/giftcenter/ > | > | > | > | > _______________________________________________________ > Send a cool gift with your E-Card > http://www.bluemountain.com/giftcenter/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=25242&t=25216 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
