Summary form only given. An evaluation of window-based gateway-to-gateway-level congestion control in an interconnected network environment is reported. Two dynamic control algorithms proposed by the author are intended to operate the system below the critical internetwork load that gives rise to congestion at gateways and connected networks. In one of the algorithms, source gateways regulate the traffic flow, whereas in the other, destination gateways provide the control. The algorithms provide further control to static window protocol by adjusting the window size in accordance with the availability of network resources at the destination. A comparison of the two algorithms has shown that controlling the internetwork messages at the destination gateway produces better performance results than control at the source gateway.