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I am very new to networking in general. For one of my assignments, I need to be able to ping two routers ( R5 must be able to ping R4 ) in different networks. SimpleTopology

For this, I set up routing in both R1 and R2. Here is the configuration for R1:

R1(config)#ip route 21.0.0.0 255.255.255.0 10.0.0.2.

and here is the route configuration for R2:

R2(config)#ip route 11.0.0.0 255.255.255.0 10.0.0.1

I might be missing an obvious thing here. R1 and R2 can ping each other. However, R2/R4 cannot ping to R5 and R1/R5 cannot ping to R4. Lets ignore the cloud and the VPC interface shown. Could anyone please tell me what is happening and what i am missing? I am a newbie and I have limited knowledge as I am just starting. I am using GNS3.

EDIT 1: Here are the routing tables so far. enter image description here

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  • Could you show us the routing table on R1 and R2 please? I feel the problem lies there. – Izy- Jan 10 '16 at 9:34
  • hi, @Izy-, thank you for the reply. I have edited the question with screenshots of the routing tables. – Bibhushan Jan 10 '16 at 10:04
  • Could you also provide us with the routing table of R4 and R5. – Indigo Jan 10 '16 at 10:55
  • Everything looks correct according to me and this may be HIGHLY irrelevant but why does your output show the routes for "RouterA" but your diagram show the router as "R1"? Could it be that you are editing the config of a different router or did you just rename it? Alternatively, I have a feeling there might be something wrong with regard to the switch? If you were to divide the network into two segments by the middle (remove the link between R1 and R2), can R1 ping R5 and R2 ping R4? – Izy- Jan 10 '16 at 10:56
  • Please show the routing tables of R4 and R5, do they actually know how to reach eachother? – Teun Vink♦ Jan 10 '16 at 11:10
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Sorry for answering rather old question.

Speaking about GNS-3: you can change the label of R1 or some other router if you stop the device (right-click the router, select stop), then right-click it and select configure.

Glad to hear you managed to add routes:

R4(config)#ip route 11.0.0.0 255.255.255.0 21.0.0.1

R5(config)# ip route 21.0.0.0 255.255.255.0 11.0.0.1

I think your problem is not solved in its entirety though - as long as R5 does not know how to reach network 10.0.0.0/24 (as a result R5 cannot ping 10.0.0.2 and vice-versa). The same goes for R4 and the network 10.0.0.0/24.

So, you should add a pair of routes:

R4(config)#ip route 10.0.0.0 255.255.255.0 21.0.0.1

R5(config)# ip route 10.0.0.0 255.255.255.0 11.0.0.1

After that all the IPs of your lab are pingable.

BTW, you could replace a pair of routes with one default route, the result would be the same. For R5 it would be:

R5#(config)ip route 0.0.0.0 0.0.0.0 11.0.0.1

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  • thank you for your reply and sorry for my even later reply. prior to your answer, i had already done the same thing, and the topology worked flawlessly. ill mark your answer correct, to show my appreciation – Bibhushan Jan 26 '16 at 9:58

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