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problem routing between three routers

ccna
Beginner
Beginner

I work with an ISP that has a cisco 1720 router to their backbone. I am installing a router on their network that will provide access to a local company via a PPP serial connection. There is a 1600 series router on both ends of the WAN segment. The 1720(router A) has an ETH0 Ip address of A.B.C.1(example) /24. I have the router that is local on that network (router B) with an IP address of A.B.C.196. I am running 10.10.10.1/24 on S0 of Router B, and 10.10.10.2/24 on S0 of router C. Router C is at the customer site with an e0 address of 192.168.100.11/24. I can ping from lan side of router C all the way back to Lan side of Router B. But from there I can't seem to get packets to go anywhere else. Router B can ping anywhere I try. All three routers are running RIP V1 on their networks. I seem to be missing something very elementary. Anyone care to help me figure this out :) I have tried various routing statements on all three routers.

Thanks.

7 Replies 7

brianj
Beginner
Beginner

Can you include the output of:

show ip protocols

show ip route

for all 3 devices?

Assuming you have the network statements correct on each of the routers you shouldn't have any problems.

Brian

The symptoms you describe are almost classic symptoms of the remote places you are trying to access do not have a route back to you.

I think that Brian is on the right track. Having the output of show ip route and show ip protocol would help analyze what the problem is.

One possibility to consider is that RIP does network summarization automatically at network boundaries. So the 192.168.100.0 network will get summarized over the 10.0.0.0 segment. And the network 10.0.0.0 will get summarized over the A.B.C.0 network. If 192.168.100.0 or 10.0.0.0 happen to appear anywhere else in the network it will produce problems.

HTH

Rick

HTH

Rick

Ok I have the information from the three routers. Thank you for your help and any suggestions you can make.

I have attached the outputs.

Just glancing at it here are my initial thoughts:

I see that you have static routes defined on router A for the 10.0.0.0 and 192.168.100 networks. Due to a lower administrative distance those will be used over any dynamic protocol.

IGRP and RIP are both running on router A. They do not redistribute automatically. Which routes to you want routers b and c to know of?

I think you are also missing some necessary network statements.

ie...

router c

network 192.168.100.0

network 10.0.0.0

I think Brian headed in the right direction. And I think that the output that you sent shows other things about the problems in your network.

Perhaps the biggest problem is that there is no dynamic routing protocol running on the serial between routerB and routerC.

I also notice in the output of show ip protocol from routerA that RIP is running on FastEthernet0 but that no updates are shown as being received. Similarly the output from routerB shows that RIP is running on Ethernet 0 but that no updates are shown as being received.

This makes me wonder whether you have been altering and hiding information in what you have sent. Or whether there is something else about the network that you have not told us.

HTH

Rick

HTH

Rick

Haven't been hiding anything. But rip had been turned off a little before that, in order to try to figure out what was going on. So I had just reenabled RIP right before that. So that is probably why there wasn't any routing statements. I wouldn't purposely hide information if I was trying to get help :) Unless it was a security issue such as the "*" I used in the public IP address. I do appreciate any help I get in this as I haven't worked with Cisco equipment very much since 2002.

Thanks.

I am glad that you have not hidden things. I asked because I have had experience in these forums where people had in fact hidden things.

In this case I suggest that you let the network stabilize and then get a new set of show ip protocol and show ip route information.

And before you do that you should think about what you want to happen over the serial link. At the time when you gathered the previous version of the information there was NO dynamic routing protocol running on the serial interfaces. (And if that was the case in the original network it could very well produce the symptoms that you originally described.)

HTH

Rick

HTH

Rick
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