Parallel TCP streams are used for data transfer between clusters in today's high performance applications. When parallel TCP streams are used on LFN, part of streams fail to get enough bandwidth because of congestion generated by the parallel TCP streams themselves [5]. As a result, data transfer throughput is bottlenecked by the slow streams. In this paper, we propose the Stream Harmonizer that schedules packet transmission of parallel TCP streams to balance the bandwidth. The purpose of the Stream Harmonizer is to reduce the congestion that is generated by the parallel TCP streams themselves to improve the performance of the slow streams. The Stream Harmonizer reduces congestion by reducing the bandwidth of fast streams by increasing the round trip time (RTT) of them. A hardware based lightweight scheduling algorithm is used to realize wire-rate intensive scheduling at highspeed backbone network. The Stream Harmonizer is able to schedule packets without exchanging additional in...