I have Cisco router 2801 with IOS 12.4. I have 2 interfaces, one serial interface with leased line connection and Ethernet interface with ADSL connection. I want to make the ADSL interface work as a backup for the serial interface. When the serial interface is down the traffic goes through the Ethernet interface and when it goes up again the traffic go through the serial. I have VPDN connection on the serial interface I want this connection to remain work and up when the traffic goes through the Ethernet (ADSL).
Could you help me???