I have a network with a 3750 as Core of the LAN. The 3750 has a default route to Router Cisco 2800. I would like add a new Cisco 2800 for high availability. How I can configure the high availability without dynamic protocol (the Cisco 3750 has a default route to the 2800 Route)? And when the external interface of the Router 2800 A is down the traffic from the LAN, be redirected to the new Cisco Router 2800 B?
I attached a picture for better understanding