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SBC T1 Internet Question with Cisco Router

macklo54 macklo54 is offline
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Join Date: May 2006
Posts: 3
I have a small network with devices attached to a 48 port switch. The switch's IP address is I wish to allow this network to access our T1 Internet. The T1 Internet router has an address of, which is already providing Internet for a 192.1.55.x network, routed through a Sonicwall gateway. In order to accomplish this, I decided to connect the T1 router to a 5port linksys switch. From this switch, one port feeds the 192.1.55.x network, and one port links to a Cisco router with two FA interfaces. The other interface connects to the 10.32.15.x network.

I configured the router accurately, because if I attach another device to the linksys switch with a 75.5.20.x address, I am able to ping this device from the 10.32.15.x network. The only thing I cannot ping is, which is the Internet router.

How do I make this complicated design work?!??!
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firecodex firecodex is offline
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Join Date: Jul 2006
Posts: 6
Its sounds like you need to call SBC and have them put a route in their router to point back to your 10.32.15.x network. There may also be an access list change needed. You can ping the 75.5.20.x network, but the router doesn't know about your 10.32.15.x network and won't know where to route the return packet.

Its either that or you use a NAT table to translate one of your outside IP's (provided via the T1 router) to the 10.32.15.x network via your cisco router.
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Zakkas Zakkas is offline
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Join Date: Apr 2006
Posts: 15
Yeah I think its a NAT issue. Basically what you'll need to do is edit your NAT entries to allow the 10.32.15.x network to get NAT'd as well. Add the 10.32.15.x subnet to the access-list on your cisco router responsible for permitting what gets NAT'd. Then on the interface on the Cisco that connects to the 10.32.15.x network apply "ip nat inside"

Last edited by Zakkas; 01-30-2007 at 04:57 PM..
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