Many research activities have focused on the problem of task scheduling in heterogeneous systems from the computational point of view. However, a scheduling strategy should also take into account the communication requirements of the applications and the communication bandwidth offered by the network. Towards this end, in this paper we first propose a model of communication cost between network nodes. This model can be used to properly characterize the existing network resources. Second, we propose a criterion to measure the suitability of each allocation of network resources to each parallel application, according to the communication requirements. Third, we propose a scheduling technique based exclusively on this criterion that provides a near-optimal mapping of processes to processors according to the communication requirements. Evaluation results show that the use of this scheduling technique fully exploits the available network bandwidth, greatly improving network performance. Therefore, the proposed scheduling technique can be used in the design of communication-aware scheduling strategies for those situations where the communication requirements are the system performance bottleneck.