This paper addresses the quantitative evaluation methodology of interconnection networks. In the conventional evaluation method, performance curves are drawn by a series of simulation runs, and network methods are discussed by comparing the shape of performance curves. We present the Ramp Load Method that does not require repetitive simulation runs and produces continuous performance curves. Based on the continuous curves, we give a formal definition of critical load ratio. Furthermore, we introduce a feature quantity to represent both throughput and average latency, and propose a new measure called Network Performance Measure. Through detailed evaluation and some application examples, the effectiveness of the proposed evaluation methodology is confirmed.