Unable to Ping external addresses

Answered Question
Mar 2nd, 2010
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Hello,

I am sorry if my question sounds ignorant, but I am somewhat new to cisco and still getting my feet wet so to speak.  My problem is that I have a 1760-v router set up at my home lab and I am unable to access IP addresses outside my local network.  I have my cisco router's fasteathernet port connected to a small netgear router which then connects to my cable modem.  The cisco router is able to ping local address fine, but when I try to ping an outside address or domain name it times out.  However, when I am at the CLI and type something like Ping google.com, it resolves google's IP address but it will not ping it.  I have IP DEFAULT-GATEWAY and IP NAME-SERVER both pointing to my netgear router and pointing to my ISP's DNS server.  I have a feeling that I am screwing up some simple entry, but can not figure it out.  Any help is appreciated


Sincerely

-Jeff

Correct Answer by Francis Garcia about 7 years 4 months ago

Hi Jeffrey,


"I have my cisco router's fasteathernet port connected to a small netgear router which then connects to my cable modem.  The cisco router is able to ping local address fine, but when I try to ping an outside address or domain name it times out. "


Regarding your case I think that we must to consider some things before going deep. is ur netgear doing NAT between ur cisco-netgear network and the netgear-Cable modem network? In case that NAT is  not enabled you must enable it in the netgear router in order to mascarade all the packets that arrives to the cable modem from the cisco-netgear network, because  the cable modem have no knowledge about the network behind the netgear router and simply discard it. In case that u dont want to use nat in the netgear router u must then make an static route in the cable modem pointing to the network behind the netgear (cisco-netgear).


Additionaly use this command in order to reach external networks

ip route 0.0.0.0 0.0.0.0 f0/0 ip-address-of-the-netgear-router


Regards

Francis

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Correct Answer
Francis Garcia Tue, 03/02/2010 - 18:03
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Hi Jeffrey,


"I have my cisco router's fasteathernet port connected to a small netgear router which then connects to my cable modem.  The cisco router is able to ping local address fine, but when I try to ping an outside address or domain name it times out. "


Regarding your case I think that we must to consider some things before going deep. is ur netgear doing NAT between ur cisco-netgear network and the netgear-Cable modem network? In case that NAT is  not enabled you must enable it in the netgear router in order to mascarade all the packets that arrives to the cable modem from the cisco-netgear network, because  the cable modem have no knowledge about the network behind the netgear router and simply discard it. In case that u dont want to use nat in the netgear router u must then make an static route in the cable modem pointing to the network behind the netgear (cisco-netgear).


Additionaly use this command in order to reach external networks

ip route 0.0.0.0 0.0.0.0 f0/0 ip-address-of-the-netgear-router


Regards

Francis

Jeffrey Miller Tue, 03/02/2010 - 18:24
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Francis,

Thank you for your fast response.  That did the trick.  Adding IP ROUTE 0.0.0.0 0.0.0.0 F0/0 192.168.0.1 (netgear IP) I am now able to ping external address.


Thanks

-Jeff

santoshagrawal Fri, 02/08/2013 - 12:03
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Great Answer Francis.


I was is the similar situation today.It worked!!!!

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