In a distributed multimedia integration environment, there is a need for transmission control methods based on real-time communication protocols, that provide a relative quality of service (QOS) to allow a variety of receiving capacities for group members and their requests and that provide a dynamic QOS to cope with temporary CPU overload and network congestion. Therefore, this study proposes a cooperative control method for end-to-end QOS control at a transport layer and for point-to-point control at a network layer. The former is mainly a set of flow-monitoring and flow-adjusting functions, and the latter a set of flow-control functions. The evaluation results show that dynamic QOS control with the two-level monitoring is preferable to conventional one in terms of the stabilization of average packet-loss rate and jitters.