We currently have a Cisco 7200 router at a remote site with a DS-3 connection to another Cisco 7200 router at the headquarters. Most traffic flow is unilateral and flows from the remote to the headquarters. We are now at a situation where this link is becoming saturated at times. We are in the process of purchasing an additional DS-3 link between the two sites, connected to the same routers. Our cost for the additional link will be based on bandwidth usage, so we would like to use this link only for excess traffic when the bandwidth of the primary link becomes saturated.
I have a few ideas on how to accomplish this, but I would like to get some feedback from the group on the best way to do this. We prefer the solution to be Cisco IOS based. We prefer not to use additional hardware unless absolutely necessary. Thank you in advance for your input.
Use the Backup interface command to accomplish this, In the primary link configure the following:
backup interface serial x.x
backup load 80 10
with this configuration, the secondary DS3 will not be activated unless the primary reaches 80% of its bandwidth utilizaton, and the primary will be active again once the threshhold decrease 10% ( the utilization becomes 70% or lesser).