The power consumption of interconnects is increased as the link bandwidth is improved in PC clusters. In this paper, we propose an on/off link activation method that uses the static analysis of the traffic in order to reduce the power consumption of Ethernet switches while maintaining the performance of PC clusters. When a link whose utilization is low is deactivated, the proposed method renews the VLAN-based paths that avoid it without creating broadcast storms. Since each host does not need to process VLAN tags, the proposed method has advantages in both simple host configuration and high portability. Evaluation results using NAS Parallel Benchmarks show that the proposed method reduces the power consumption of switches by up to 37% without performance degradation.