Analysis and Optimization of Two-Tier Networks with Application to Optical Transport Backbones

Networks are often partitioned into tiers to provide a convenient framework for the optimization, graceful growth, and evolution of the network. In this paper we extend the application of the Network Global Expectation Model, which we have recently described, by considering a two-tier architecture for a communication network and analyzing the corresponding network requirements and costs using expectation values evaluated over the entire network. We also explicitly treat non-uniform traffic in the form of population-dependent demand. The capability of the model is illustrated by demonstrating scenarios for which the two-tier architecture may be used to reduce the cost of the network relative to a single-tier solution.