In this paper, we propose, verify and evaluate a method combining cross-layer method and bandwidth allocation to overcome the difficulty of flow control in a network with large bandwidth delay product. When the bandwidth delay product is large, there are problems with the convergence time, efficiency and stability of bandwidth utilization, fairness among traffics of different round-trip time. As a result of examining the conventional methods, we propose a novel method which can be realized as a functional addition to the existing TCP flow control with improvement in utilization efficiency, fairness, stability and convergence time. The method is compared with TCP Reno, FAST TCP, CUBIC, ECN and XCP by simulation, and is confirmed as having good characteristics.