Network architecture design is the operational framework that begins, at the top level, with capacity design, then works through to the transport and nodal function designs, and finally generates directions for engineering design. In the process, a network architect is faced with the question of balancing the pursuit of his own architecture while managing commercial vendors' influences. In this article, we seek to develop techniques and methodologies for modeling and optimizing the metro network architecture with an emphasis on network capacity planning. Capacity planning directs subsequent architectural and engineering designs. We first discuss how to build metro network models and generate executable procedures of the network analysis. The metro network is described as an object-oriented network with an integration of traffic sites and network entities. The traffic demand, network connectivity and traffic processing are the main object functions that have to be modeled. Cost modeling, which is used to link the architecture with its capital expense, is briefly reviewed. Cost models are established with capacity demands allocated to network functioning points. Afterwards, equipment allocation is performed to determine the network devices needed. Finally, the authors show how to perform network design optimization. The optimization processes are executed on a search engine to produce the best combination of variables of the network entities.