Unable to Ping

[simon.hutton1]

First let me apologize for posting probably such a simple question but i'm new to configuring routers so please be nice :) I have installed a 2nd router on our network (my first router config) from this router I can get out to the rest of the network and Internet no problem however I am not able to access any computer connected to the new router. There are 2 networks configured on the new router 10.20.4.0/10.20.5.0. I can ping the router and connect to it over my network, I can ping 10.20.4.1 and 5.1 but the laptop I connect which, has IP address 10.20.4.2, I am unable to ping.

[John Blakley]

Please draw a diagram and I can help further...

[simon.hutton1]

Thank you for all the help. Attached is a very quick basic diagram of the current setup. I am physically sat at Laptop A and Laptop B is in the server room connected directly to FE 0/1 Hope this helps.

[John Blakley]

Ah okay...I get it now. I believe your problem is your natting. If everything is in your control, there's no need to nat.

Look at it from this perspective. At this point, the only networks RouterA knows about are its networks which are 10.20.0.0/22 (10.20.0.0 - 10.20.3.255). With nat enabled, your 10.20.4.0 and 10.20.5.0 networks are reaching RouterA as the natted address of 10.20.3.253. When you're trying to ping 10.20.4.x from LaptopA, you can't because that network doesn't exist to RouterA, so it's sending to the default route.

What I would do is remove all natting from the fa0/0 interface on RouterB. Your rip process should be able to route this correctly. Personally, I'd also add "version 2" under the rip process unless you're neighboring with a device that doesn't support version 2. If you're not, you'll be in a better position since version 1 is classful.

In summary:

Remove "ip nat out" from g0/0.

Give it a few minutes for rip to catch up and then try again.

HTH,

John

[simon.hutton1]

Thanks for the help. I have removed NAT and changed RIP to version 2. Just waiting now to see if that fixes it.

[John Blakley]

Make sure that you change the version on both routers. You can see the rip database with "show ip rip database" to see if your routes are there.

[simon.hutton1]

Thanks for all the help today. I'm still not able to Ping Router B from Laptop A. I've removed NAT and changed RIP to V2 but my Pings still fail. If everything looks OK on Router B in your opinion I'll take a look at Router A to make sure everything is OK there but I would have thought it would be.

[John Blakley]

At this point, can you post a "show ip route" from both routers?

[simon.hutton1]

I removed the Nat from 0/0 and changed RIP to v2. After that Laptop B was not able to get out to the Internet or internal network. I enable Nat on 0/0 and Internet/network connection comes back. Attached are the 2 show ip routes

[John Blakley · Accepted solution]

There are no rip learned routes in the routing table. Did you ever have rip routes, or did you just configure it and it not work? If you do a "show ip rip database" on both routers, do you get anything back?

If not, you could always put your static routes on routerA. This is the exact reason why you lost internet access when you removed nat. The only network RouterA knows about is 10.20.0.0/22 which your 10.20.3.0 falls into. When you nat, all of your traffic is going out of routerB as the 10.20.3.253 wan address. Before you can remove nat though, you'll need to get the routing fixed on RouterA.

Try 10.20.4.0 <netmask> with a next hop of 10.20.3.253. Remove nat again and try again...

John

[simon.hutton1]

Thank you for your help. all works fine now :) Router A was at fault doesn't look like it has RIP enabled so added static route, disabled NAT on Router B and all is OK. Thank you again.

[John Blakley · Accepted solution]

Glad to hear it! Can you please mark this as resolved?

Thanks!

John