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New Member

cisco 3640 router

i upgrade from a 2611 to a 3640 router. I am trying to get my home network on the internet. I have tried to configure the router and setup nat overload, but i can't get to the internet. I can ping both nics on the router and i can pping my switch



description Internal

no shutdown

ip nat inside


ip dhcp

description Internet

no shutdown

ip nat outside

ip access-list standard 1


ip nat inside source list 1 interface ethernet0/1

ip route ethernet0/1


Re: cisco 3640 router

can you ping an IP address in internet: for example an external DNS?

can you paste the show ip route?

Hall of Fame Super Silver

Re: cisco 3640 router


The first thing that I would like to verify is whether your router is communicating with the provider router and whether your router is being assigned an IP address on interface ethernet0/1. If it is not then obviously this is the main problem and you need to resolve it.

If the interface is being assigned an IP address then I agree that the next thing to verify is whether the router can ping some Internet resource. Perhaps an external DNS server would be a good target. And ping by address rather than by name so that DNS resolution is removed as a potential variable.

I am guessing that the ping may fail. If the ping does fail then I would suggest that the problem may be in the static default route. You have configured this:

ip route ethernet0/1

but configuring a static route pointing at an interface requires that the router ARP for every remote address to which it is attempting to forward. And to succeed it is dependent on the provider enabling proxy arp. I am guessing that the provider is perhaps not enabling proxy arp. I would suggest that you change your static default route to this;

ip route dhcp

If the ping does succeed, or if changing the static default route does not resolve the problem then we will need some additional information. Please post the output of show ip interface brief and of show ip route. It might also be helpful if you would post the entire router config.



New Member

Re: cisco 3640 router


Add "overload" to your nat statement as follows:

ip nat inside source list 1 interface ethernet0/1 overload


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