A major issue in modelling the performance merits of interconnection network is dealing with virtual channels. Some analytical models chose not to deal with this issue at all i.e. one virtual channel per physical channel. More sophisticated models, however, relayed on a method proposed by Dally to capture the effect of arranging the physical channel into many virtual channels. In this study, we investigate the accuracy of Dally's method and propose an alternative approach to deal with virtual channels in analytical performance modelling. The new method is validated via simulation experiments and results reveal its accuracy under different traffic conditions