It is very important to allocate and manage resources for multimedia type of data traffic flows with real-time performance requirements in order to guarantee quality-of-service (QoS). In this paper, we develop a scalable architecture and an algorithm for access control of real-time flows. Since individual management of each traffic flow on each transit router can cause a fundamental scalability problem in both data and control planes, we consider that each flow is classified at the ingress router and data flow is aggregated according to the class inside the core network as in a DiffServ framework. In our approach, access decision is made for each flow at the edge routers, but it is scalable because per-flow states are not maintained and the access algorithm is simple. In the proposed access control scheme, an admissible bandwidth, which is defined as the maximum rate of a flow that can be accommodated additionally while satisfying the delay performance requirements for both existing and new flows, is calculated based on the available bandwidth measured by edge routers. The admissible bandwidth is a entry for access control, and thus, it is very important to accurately estimate the acceptable bandwidth. The performance of the proposed algorithm is evaluated by taking a set of simulation experiments using bursty traffic flows.