I have a cable modem with static address run to gi0/1 on a Cisco 2821 ios Version 12.4(15)T10. The gi0/1 has dhcp enabled (carrier uses mac to give out address reservation). This is the primary internet carrier. The local lan is on gi0/0, which has another cisco router on it used by another entity that has internet access from another carrier.
I need to have the 2821 direct traffic to that device when the gi0/1 interface can no longer get outbound. i have tried static routes, such as 0.0.0.0 0.0.0.0 gi0/1 and 0.0.0.0 0.0.0.0 otherrouter address 250 but that results in the other router getting all of the traffic. This resuts in a far slower internet, as its a low speed backup T1. I need guidance on making the SLA or whatever is the best fit for this to work.