How do you create a Serial Subinterface on a Cisco 2811 router. This is for a WAN lab. I have a another Cisco 2811 router that was preconfigured with the serial subinterface withe following IOS flash:c2800nm-ipbase-mz.124-3g.bin. The Cisco 2811 router that I'm unable to create a subinterface on has the follwoing IOS flash:c2800nm-advsecurityk9-mz.124-15.T9.bin. i'm not sure if the IOS is the problem or I'm usign the wrong commands.
I have this problem too.