We are looking into getting a second data circuit as a to the primary circuit. The question is if the primary circuit goes down how would the outside know to route the traffic through the second circuit. Here is our current setup. We have a main location with about 15 remote sites that connect back to the main location via site to site tVPN tunnels. The VPN router at both ends have an associated public IP. If the main circuit went down, I would have to reconfigure everything to use the IP schema associated with the backup circuit. I know they have load balancers that balance traffic between muliple ISPs they seem to load balance out going traffic. Does this mean that I would require a unit at every location? Is there a better way of doing this. I am looking for fault tolerance more than load balancing although both would be nice.