Nat issue?

[supergino]

Hey Guys, im new to this site and looks like a good one but got a problem I just cant seem to get a hold of.

I have a GNET modem I have some questions about. Currently I have a Cisco 2611 router, 2916XL switch and my internal host on my network connected to my switch. Curently, I have the Gnet modem authenticating on the adsl network since my IOS doesn’t support PPPoE and I can’t get past the modem to the internet. The modem has an internal interface with an IP address of 192.168.7.1/24 so I gave my router a .2 ip on the same subnet via E0/0 interface. My LAN IP is a 192.168.1.0/24 subnet using the E0/1 interface.

Since I can ping the GNET modem and all my hosts on my internal LAN segment from my router, I don’t believe I have a config issue but my hosts are not able to ping the GNET modem. My host is able to ping both interfaces on my 2611 router and my trace route shows the ping all the way to my default gateway but then no response.

Heres my config. Maybe this will help too.
Current configuration:

!

version 12.0

service timestamps debug uptime

service timestamps log uptime

no service password-encryption

!

hostname Cisco2611

!

boot system flash c2600-i-mz.120-7.bin

enable secret 5 $1$.exe$ZPEWaIocuAMp23nrBIREk1

!

!

!

!

!

ip subnet-zero

ip name-server 192.168.7.1

!

!

!

! interface Ethernet0/0

ip address 192.168.7.2 255.255.255.0

no ip directed-broadcast

full-duplex

!

interface Serial0/0

no ip address

no ip directed-broadcast

no ip mroute-cache

shutdown

no fair-queue

!

interface Ethernet0/1

ip address 192.168.1.1 255.255.255.0

no ip directed-broadcast

half-duplex

!

interface Ethernet0/1.1

no ip directed-broadcast

!

router rip

network 192.168.7.0

!

ip default-gateway 192.168.7.1

ip classless

no ip http server

!

!

line con 0

transport input none

line aux 0

line vty 0 4

password cisco

login

!

no scheduler allocate

end

Thanks

Steve

 

[megaco]

Does your GNet support NAT?

All 192. addresses are private address blocks and will not work on the Internet. My guess is that the Gnet is also using a public address - this is what you need to be doing NAT on.

If your Gnet does not support NAT then you might have to replace it with one that does

I work for IDL (

http://www.idl-mettoni.com)

and my website is

http://www.call.uk.net

 

[megaco]

In fact if your Gnet is using a 192. address then it is support NAT lol.

How do you configure the Gnet?

I work for IDL (

http://www.idl-mettoni.com)

and my website is

http://www.call.uk.net

 

[JOAMON]

Router rip....
needs:
version 2
network 192.168.1.0

set default ip route
ip route 0.0.0.0 0.0.0.0 192.168.7.1

If GNET modem is not already doing NAT the you can do the following
inteface ethernet 0/1
ip nat inside

interface ethernet 0/0
ip nat outside

ip nat inside source list 10 interface ethernet 0/0 overload

access-list 10 permit 192.168.1.0 0.0.0.255

You might also consider changing ethernet 0/0 back to half duplex. I have had previous problems with cisco 2611 in full duplex mode when not connected to a Cisco switch which was hard set to 10/full. Do a show interface ethernet 0/0 and see if there are any errors on the interface.

 

[supergino]

Hey guys,

Currently my GNET is doing the NAT translation for me. I don't have anything configured on it except NAT on teh GNET. As far as I can tell, thats all the modem is doing. Its just doing authentication to the DSLAM switch so it can get the public IP. I tried switching the ethernet 0/0 to half duplex and it was the same issue with no change. Adding in the default route didnt change anything either.

Gateway of last resort is 192.168.7.1 to network 0.0.0.0

69.0.0.0/32 is subnetted, 2 subnets
R 69.28.196.11 [120/1] via 192.168.7.1, 00:00:03, Ethernet0/0
R 69.28.199.126 [120/1] via 192.168.7.1, 00:00:03, Ethernet0/0
65.0.0.0/32 is subnetted, 2 subnets
R 65.39.192.130 [120/1] via 192.168.7.1, 00:00:03, Ethernet0/0
R 65.39.134.4 [120/1] via 192.168.7.1, 00:00:03, Ethernet0/0
C 192.168.7.0/24 is directly connected, Ethernet0/0
C 192.168.1.0/24 is directly connected, Ethernet0/1
R* 0.0.0.0/0 [120/1] via 192.168.7.1, 00:00:03, Ethernet0/0

My config hasn't changed because all my updates are in RIP 1 anyway on the GNET modem. If the Modem is running RIP 1 and I run RIP 2 between the modem and the router wouldnt that cause other issues?

Also, if I run RIP and I enter in a static default route, I get an exception on the router and it reboots. But you can see my candidate default route is already in my routing table. It would be correct.

More info, if I check my modem for a NAT translation, I dont see it until I plug in my NIC directly to the modem and then I see translations from my NIC card. Once I put my PC on the 192.168.1.0 subnet, nothing works. I can ping both interfaces on the router but it wont go past that.

 

[JOAMON]

Leave RIP as version 1 but add 192.168.1.0 network
How are you configuring the PC's IP settings. Can you ping 206.163.82.4 from a command prompt. If so then what happens if you ping

http://www.gmc.com...does

it resolve the name to a physical address??

 

[supergino]

Nope. no DNS resolution. unknown host every time. Tracert dies at 192.168.1.1 and never gets past it. I cant ping anything past 192.168.7.2 (ethernet e0/0).

 

[supergino]

Sorry. Forgot to add in the IP settings...

IP: 192.168.1.12
netmask 255.255.255.0
Default Gateway: 192.168.1.1
DNS: 192.168.7.1 (tried 1.1 but same result)

 

[supergino]

Got it figured out. The GNET modem didnt have a route back to the 192.168.1.0 network which is why the packets wouldnt come back to the destination.
Thanks for all your help guys.