Many topological network design problems in manufacturing and service systems can be modelled with closed queueing networks, finite buffers, and multiple-servers. Because of their integrality, it is difficult to predict the performance of these problems, let alone optimize their parameters. This paper presents a new queue decomposition approach for the modelling of these finite buffer closed queueing networks with multiple servers along with an integrated approach to the optimization of the allocation of the servers in the network topology. The performance and optimization algorithms are described and a number of experiments for series, merge, and split topologies together with the integration of material handling and layout systems are carried out.