Setting pre-congestion notification admission and preemption thresholds in computer networks

A method and apparatus for setting admission and preemption thresholds in a computer network are disclosed. In one embodiment, a method includes receiving traffic information including a first bandwidth utilization on each link located between ingress nodes and egress nodes based on a traffic matrix with no failures at the nodes or the links, and a second bandwidth utilization on each of the links based on the traffic matrix with planned failures at one or more of the links or the nodes. A preemption-to-admission ratio is calculated based on the first and second bandwidth utilizations on the links. An admission threshold is calculated at one of the links based on the second bandwidth utilization on the link and the preemption-to-admission ratio. At least one of the preemption-to-admission ratio and admission threshold is transmitted to a network device for use in flow admission.