In this paper, we present a bandwidth-centric parallel job communication model that takes into account intercluster network utilization as a means by which to capture the interaction and impact of simultaneously co-allocated jobs in a mini-grid. Our model captures the time-varying utilization of shared inter-cluster network resources in the grid. We compare our dynamic model with previous research that utilizes a .xed execution time penalty for co-allocated jobs. We have found that the fixed penalty model is more generous in its prediction of job turnaround time than our dynamic communication model. Additionally, we see that the penalty co-allocated jobs may experience without causing a severe performance degradation decreases as the number of clusters increases.