Optimizing restoration capacity in the AT&T network

To ensure high network reliability, AT&T employs two basic approaches: preventing failures and responding quickly when failures occur. For AT&T to quickly reroute traffic in the event of a network failure, the network must contain sufficient restoration capacity to carry the displaced demand. A team of AT&T OR experts, network planners, and managers developed a method for determining the appropriate quantity and location of restoration capacity required to restore the demand during any single link failure. The approach centers on a linear programming model to minimize the cost of the restoration network and uses column generation to generate new restoration paths as needed. In about: 10 months, the team converted the methodology into a tool to optimize the allocation of restoration capacity. This tool was then extended to plan for the recovery of a switching-center disaster and to reoptimize the entire restoration ne network. It has contributed to AT&T's achieving high-quality service, while saving valuable resources, It resulted in hundreds of millions of dollars in cost savings and increased revenues.