Techniques for Probabilistic Multi-Layer Network Analysis

We describe a prototype tool that analyzes combined aspects of reliability and performance for a variety of networks. Our network-wide analysis systematically generates failure scenarios (called network states), maps their effects from the physical to the network to the traffic layer, calculates the probability of each state, and evaluates a metric on it, until the expected value of the metric or a point on its distribution is estimated to sufficient accuracy. We describe an application of this multi-layer probabilistic methodology to dealing with partial link failures in an ISP backbone network.