One of the important parameters which determines the performance of communication networks is network availability or network reliability. The network reliability strongly depends on not only the topological layout of the communication networks but also the reliability and availability of the communication facilities. The selection of optimal network topology is an NP-hard problem so that the enumeration-based methods grow exponentially with network size. This paper presents a new solution approach based on discrete particle swarm optimization (d_PSO) to design of communication networks. The design problem is to find the optimal network topology where total cost is minimum and all-terminal reliability is not less-than a given level of reliability. The effectiveness of the d_PSO is investigated comparing its results with those of obtained by GA given in the literature for the design problem. Computational results show that the d_PSO is an effective heuristic approach to design of reliable networks.